predicting prognosis of hcc - conplus.co.krkcr2019/down/abs/ss/kcr 2019 abstract book … · mri...

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SF 10 AB-01 Hot issues in liver imaging 14:00 - 14:30 Grand Ballroom 104

Chairperson(s): Chang Hee Lee Korea University Guro Hospital, Korea Mi-Suk Park Yonsei University School of Medicine, Severance Hospital, Korea

Predicting prognosis of HCC

Sunyoung LeeYonsei University School of Medicine, Severance Hospital, Korea. [email protected]

We discuss MR imaging features that have been reported to be related to aggressiveness and poor prognosis of hepatocellular carcinoma (HCC) but not included in the current staging systems: findings associated with worse histologic grade, microvascular invasion, presence of satellite nodules, and progenitor cell marker. Current evidence suggests that non-smooth

tumor margin, irregular rim-like enhancement in the arterial phase, peritumoral enhancement in the arterial phase, hypointense HCC in the hepatobiliary phase, peritumoral hypointensity in the hepatobiliary phase, and restricted diffusion are related to poor prognosis of HCC, reflecting aggressive tumor biology.

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State-of-the-art MR imaging of the liver

Jeong Hee YoonSeoul National University Hospital, Korea. [email protected]

MRI has been widely used for liver imaging for lesion detection and lesion characterization, owing to its superior soft tissue contrast compared with other imaging modalities and hepatocyte specific contrast media. Further, it is also able to provide multiparametric images. It can be used for quantification of variable contents, treatment response evaluation, and diffuse liver disease evaluation. To exploit capability of liver MRI, continuous technical development is needed in parallel with clinical validation. In this talk, recent technical development and expanded clinical indications are addressed with basic l iver MRI sequences. Technical development focuses on multiphasic arterial

phase image acquisition, free-breathing acquisition, and shorter acquisition time that have reduced examination failure and widen applicable population. In addition, quantification techniques of diffuse liver disease and treatment response evaluation are also addressed, focusing on tissue mapping, diffusion weighted imaging with different models, and perfusion with or without contrast media. By implementing those techniques, we can obtain liver MRI with more confidence on the image quality than before. Further, liver MRI using aforementioned techniques can provide comprehensive information of the liver non-invasively that allows us to understand the pathophysiology of the liver.

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Issue on LI-RADS v2018

Sang Hyun Choi University of Ulsan College of Medicine, Asan Medical Center, Korea. [email protected]

Hepatocel lular carcinoma (HCC) is the most common primary hepatic malignancy and the third most frequent cause of cancer-related deaths (1, 2). Unlike most other cancers, noninvasive diagnosis based on imaging characteristics without mandatory pathologic confirmation is unique feature. Many advances have been made in contrast-enhanced magnetic resonance imaging (MRI) including the use of hepatocyte-specific contrast agents, and it resulted in the improved sensitivity in detecting small HCCs (3). However, the imaging diagnosis of HCC have been confused and inconsistent in its application in both clinical care and research because no established consensus regarding the exact definition of imaging diagnostic criteria (4).

To standardize performance of liver imaging in patients at risk for HCC as well as interpretation and reporting of the results, the Liver Imaging Reporting and Data System (LI-RADS) was introduced in 2011 (4), recently updated in 2018 (5). In 2018, the American Association for the Study of Liver Disease (AASLD) integrated LI-RADS into its clinical practice guidance for HCC (5). This was an important step for radiology’s involvement in the care path of this patient population, since HCC is one of the only malignancies that can be treated based on imaging alone, without the need for pathologic confirmation (6).

This integration required a few changes in the CT/MRI algorithm of LI-RADS, released as ‘‘version 2018’’. The main areas of change include simplification of the definition of threshold growth, update to one of the LR-5 criteria, and the removal of the qualifiers -us and -g from LR-5 category. The definition of threshold growth was simplified to match that of Organ Procurement and Transplantation Network (OPTN): ≥ 50% size increase of a mass in ≤ 6 months. Additional definitions of growth that qualified as threshold growth in the prior versions of LI-RADS now qualify as subthreshold growth, which is considered an ancillary rather than a major feature (7). In addition, the requirement of US visibility was removed

in v2018, so that 10-19 mm observations with nonrim APHE and nonperipheral ‘‘washout’’ are categorized LR-5 (without any modifier).

LI-RADS is accepted and widely used in the clinical practice, and many studies have reported the clinical results of liver imaging, i.e., ultrasound, computed tomography, and MRI, in the diagnosis of HCC using LI-RADS. Therefore, it is important to know the changes in the updated version of LI-RADS and to understand the present advantage and weakness of LI-RADS. In this lecture, I will briefly introduce what is new in LI-RADS version 2018 and summarize the clinical results of LI-RADS which had been reported in previous literatures, using a systematic review and meta-analysis.

References

1. El-Serag HB. Hepatocellular carcinoma. N Engl J Med 2011;365:1118-1127

2. El-Serag HB, Rudolph KL. Hepatocellular carcinoma: epidemiology and molecular carc inogenesis. Gastroenterology 2007;132:2557-2576

3. Lee YJ, Lee JM, Lee JS, Lee HY, Park BH, Kim YH, et al. Hepatocellular carcinoma: diagnostic performance of multidetector CT and MR imaging-a systematic review and meta-analysis. Radiology 2015;275:97-109

4. Mitchell DG, Bruix J, Sherman M, Sirlin CB. LI-RADS (Liver Imaging Reporting and Data System): summary, discussion, and consensus of the LI-RADS Management Working Group and future directions. Hepatology 2015;61:1056-1065

5. Marrero JA, Kulik LM, Sirl in CB, Zhu AX, Finn RS, Abecassis MM, et al. Diagnosis, staging, and management of hepatocellular carcinoma: 2018 practice guidance by the American Association for the study of liver diseases. Hepatology 2018;68:723-750

6. Kielar AZ, Chernyak V, Bashir MR, Do RK, Fowler KJ, Santillan C, et al. An update for LI-RADS: version 2018. Why so soon after version 2017? J Magn Reson

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Imaging 2019 7. Kielar AZ, Elsayes KM, Chernyak V, Tang A, Sirlin CB.

LI-RADS version 2018: what is new and what does

this mean to my radiology reports? Abdom Radiol (NY) 2019;44:41-42

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Recently, quantitative analysis from diffusion-weighted MRI and CT-based texture analysis allows the usage of multiple imaging biomarkers to evaluate the aggressiveness, treatment response and prognosis of gastric cancer.

In addition to preoperative assessment, CT has a primary role in postsurgical surveillance of gastric cancer. In particular, extragastric recurrence is mostly diagnosed with abdominopelvic CT, while gastric recurrence is usually confirmed by endoscopy. Although abdominopelvic CT scans are most commonly included in postsurgical surveillance in many institutions, we could rarely detect recurrence on many postoperative CT scans, probably due to the low incidence of extragastric recurrence after surgical resection of early gastric cancer. Therefore, it might be unnecessary to perform post-surgical CT surveillance in all patients with early gastric cancer.

In this lecture, we will discuss the role of CT in preoperative staging and CT findings of stomach cancer according to AJCC 8th TNM staging. We also discuss the efficacy and the potential role of MRI for preoperative assessment, and stratification of postsurgical CT surveillance in patients with early gastric cancer.

SF 17 AB-01 GI tract: revisited 14:00 - 14:30 Grand Ballroom 103

Chairperson(s): Se Hyung Kim Seoul National University Hospital, Korea Seong Ho Park University of Ulsan College of Medicine, Asan Medical Center, Korea

Update of stomach imaging

Nieun Seo Yonsei University College of Medicine, Severance Hospital, Korea. [email protected]

The stomach may be affected by various pathologies such as carcinoma, lymphoma, or gastritis. Gastric carcinoma is one of the most common causes of stomach imaging, particularly in prevalent countries. Complete surgical resection of gastric cancer and regional lymphadenectomy has been usually considered to be the only potentially curative treatment. However, introduction of endoscopic resection to treat early gastric cancer and chemotherapeutic agents to treat advanced disease provides more dedicated treatment options. Therefore, accurate preoperative assessment is critical for deciding treatment plan and potentially improving patient’s outcome. Computed tomography (CT) is the standard imaging modality used in preoperative gastric cancer staging for evaluating the local tumor extent, involvement of lymph nodes, and distant metastasis. Technical advances in CT using thin section thickness, optimal contrast enhancement and mult iplanar reformation has improved diagnostic performance for preoperative staging. Although magnetic resonance imaging (MRI) has not been widely used to assess gastric cancer due to its intrinsic limitations, excellent soft tissue contrast and development of rapid imaging sequences may enable MRI to be a feasible modality.

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GI tract imaging

Hongmei ZhangNational Cancer Center / Cancer Hospital, China. [email protected]

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Standardized approach for rectal MRI

Sung Kyoung Moon Kyung Hee University Hospital, Korea. [email protected]

Rectal MRI is the most accurate modality to define locoregional clinical staging of rectal cancer. It allows determine the T substage, circumferential resection margin (CRM), and extramural vascular invasion (EMVI). MR findings and features can predict the risks of local recurrence and synchronous /metachronous distant metastases. MR assessment is the core to select patients for the preoperative management and to define the extent of surgery. It is the best in assessing the relationship of tumor and mesorectal fascia (MRF) which is crucial in decision-making.

The systematic or standardized approach from the image acquisition to the reporting of rectal MRI ensures all clinically relevant structures of the rectal cancer. A standard proforma or reporting form of rectal MRI facilitates surgical planning and leads to a confidence and higher satisfaction of referring surgeons to make a decision.

In this lecture, standardized scan technique, and reporting of staging, margin status related with the surgical planes, EMVI, and tumor regression grade after preoperative treatment will be discussed.

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SS 05 AB-01 Liver MRI: techniques and application 09:50 - 10:20 Grand Ballroom 105

Chairperson(s): Jeong Min Lee Seoul National University College of Medicine, Korea Seung Soo Lee Asan Medical Center, Korea

Liver MRI. Video will not kill the radio star

Guido Kukuk Bonn University / Kantonsspital Graubünden, Germany. [email protected]

Radiology becomes increasingly important for early detection, accurate assessment and follow up of focal and diffuse liver disease. Among all available liver imaging modalities MRI combines the most refined techniques in order to meet future challenges. We

discuss current and upcoming imaging techniques and quantitative methods with regard to histopathology as the current gold standard in order to assess liver disease.

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Abdomen 09:50 - 11:20 Grand Ballroom 105

Liver MRI: techniques and application

Chairperson(s)Jeong Min Lee Seoul National University College of

Medicine, KoreaSeung Soo Lee Asan Medical Center, Korea

SS 05 AB-02 10:20 Dual arterial phase MR imaging with gadoxetic acid using a slow contrast injection method (0.5 cc/sec): a solution for transient motion artifact?Jae Chun Park, Myeong jin Choi, Jung Gu Park, Kyung Seung Oh Kosin University Gospel Hospital, Korea. [email protected]

PURPOSE: To evaluate the onset time and duration of transient dyspnea and to determine whether slow contrast injection method (0.5 cc/sec) reduces gadoxetate-disodium-associated transient motion artifact in magnetic resonance imaging (MRI) of the liver.MATERIALS AND METHODS: In 277 patients who had received gadoxetate disodium by two injection methods (1 cc/sec: 143, 0.5 cc/sec: 144 patents), double arterial phases were obtained with two breath-hold under MR fluoroscopy guidance. In 144 patients who had received 0.5 cc/sec injection method, the onset time and duration of transient dyspnea was evaluated via recorded respiratory motion graph. Arterial phase timing accuracy and severity of motion artifacts were rated on a four-point scale. Interreader agreement was calculated by weighted kappa. Continuous variables were compared via a two sided ANOVA, categorical variables via a χ2 test.RESULTS: Transient dyspnea occurred in 14% of patients. The mean time to the onset of transient dyspnea was 45.6 seconds after contrast injection and transient dyspnea persisted for an average of 14 seconds. A 0.5 cc/sec injection method improved correct late arterial timing rates and reduced motion-related image deterioration rates. In 2nd arterial phase, optimal arterial liver visualization was achieved in 88.9% (0.5 cc/sec) compared with 66.4% (1 cc/sec) (p < 0.001). In two arterial phases, the severity of motion artifacts showed no significant difference (p = 0.265, 0.155).CONCLUSION: The 0.5 cc injection method may be useful in obtaining optimal arterial phase images and avoiding transient dyspnea time in gadoxetate-enhanced dynamic MRI of the liver.

SS 05 AB-03 10:30 Feasibility of free breathing dynamic T1WI liver MRI using compressed sensing golden angle radial sparse parallel imaging (CS-GRASP)Jinyoung Park1, Jeong Hee Yoon2, Sang Min Lee3, Jeong Sub Lee4, Ji Yeon Han1, Hae Woong Jeong1, Seong Sook Cha1 1Inje University Busan Paik Hospital, 2Seoul National University Hospital, 3Hallym University Sacred Heart Hospital, 4Jeju National University Hospital, Korea. [email protected]

PURPOSE: Arterial hyperenhancement is major component o f non invas ive imaging gu ide l ine of hepatocellular carcinoma. Evaluating arterial enhancement may be often problematic on liver MRI due to transient dyspnea and in real practice there are patients who cannot hold their breath even for short seconds. This study is aimed to find out clinical feasibility of free breathing gadoxetic acid enhanced dynamic T1 weighted imaging (T1WI) using compressed sensing golden angle radial sparse parallel imaging (CS-GRASP).MATERIALS AND METHODS: From March to May 2018, 41 patients who could not hold their breath underwent liver MRI including dynamic T1WI using free breathing CS-GRASP. Two radiologists analyzed pre, early-, late arterial and portal phase imaging independently. On each phase, motion, streak artifacts and overall image quality were evaluated on a four-point scale as the higher score indicated better image quality and less artifact.RESULTS: In 41 patients (30 male, 11 female), age ranged from 52 to 98 and mean age was 67.5. Motion artifact scores were 3.17 ± 0.52, 3.21 ± 0.52, 3.21 ± 0.54, and 3.43 ± 0.55 on precontrast, early arterial (EA), late arterial (LA) and portal phases, respectively. Overall image quality scores were 2.73 ± 0.6, 2.99 ± 0.63, 3.39 ± 0.6, and 3.63 ± 0.53, on precontrast, EA, LA and portal phases. In 94% and 98% of 41 patients, late arterial and portal venous phase showed acceptable image quality that did not need re-examination.CONCLUSION: Free-breathing dynamic T1WI with CS-GRASP may have potential usefulness in patient with history or high risk of breath holding failure in liver MRI.

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SS 05 AB-04 10:40 Metabolic alterations associated with development of hepatocellular carcinoma in patients with hepatitis-induced liver cirrhosis: in vivo 1H MR spectroscopySeunggwi Park1, Sang Soo Shin2, Suk Hee Heo2, Yong Yeon Jeong2 1Chonnam National University Hwasun Hospital, 2Chonnam National University Medical School, Korea. [email protected]

PURPOSE: Liver cirrhosis (LC) secondary to chronic hepatitis can lead to serious complications. In severe cases, liver cirrhotic patients can develop hepatocellular carcinoma (HCC), and therefore monitoring disease progression is clinically important. The purpose of this study was to quantify the hepatic metabolites of normal control (NC), LC, cirrhotic liver with HCC (CLH) and HCC using in vivo proton magnetic resonance spectroscopy (1H-MRS) with a long echo-time (TE) and assess their associations with aging and enzymatic activity.MATERIALS AND METHODS: Thirty patients with LC, 30 cirrhotic patients with HCC, and 30 NCs were included in this study. Liver cirrhosis in all patients with LC were attributable to hepatitis B virus and hepatitis C virus. 1H-MRS measurements were performed on a localized voxel of liver parenchyma using a 3-T MR scanner to compare the differences in hepatic metabolites among four groups. A mediation analysis was used to assess the association between ages and cellular metabolite levels with the mediation effect of serum enzymatic activities. In addition, a receiver operating characteristics (ROC) curve analysis was conducted to evaluate the diagnostic performance of 1H-MRS to predict the development of HCC in patients with hepatitis-induced cirrhotic liver.RESULTS: The levels of lactate + triglyceride (Lac+TG) and choline (Cho) were significantly different between LC and HCC, and between CLH and HCC. Also, Lac+TG and Cho levels were positively correlated with lactate dehydrogenase (LDH) activity and alkaline phosphatase (ALP) activity, respectively. Lac+TG concentrations were positively correlated with ages. The total effect of the patient age on Lac+TG alteration was significant, and was fully mediated by LDH levels in LC, CLH, and HCC groups. In cirrhotic patients, the AUC to distinguish HCC from LC was 1.00 (95% CI 1.00-1.00) for Lac+TG and 0.876 (95% CI 0.79-0.96) (p < 0.001) for Cho. In addition, the AUC to distinguish HCC from CLH was 1.00 (95% CI 1.00-1.00) for Lac+TG and 0.872 (95% CI 0.77-0.97) for Cho (p < 0.001).CONCLUSION: In vivo 1H-MRS was useful to quantify hepatic Lac+TG and Cho levels in both cirrhotic liver and HCC, where higher Lac+TG and Cho values may

be more likely related to the development of HCC in the cirrhotic liver. Further, the level of Lac+TG increased with older age, mediated by LDH levels.

SS 05 AB-05 10:50 Comparison of spin-echo echo-planar imaging MR elastography with gradient-recalled echo MR elastography and correlation with transient elastographyEun Sun Lee1, Hyun Jeong Park2 1Chung-Ang University Hospital, 2Chung-Ang University Medical Center, Korea. [email protected]

PURPOSE: To compare the liver stiffness (LS) values obtained by newly developed spin-echo echo-planar imaging (SE-EPI) MR elastography (MRE) with conventional gradient-recalled echo (GRE) MRE in the same condition. In addition, to assess the statistical correlation of the obtained LS values with those of transient elastography (TE).MATERIALS AND METHODS: From November 2017 to April 2019, we retrospectively included study population who underwent liver MRE with both SE-EPI and GRE sequences in the same session. Among them, we excluded patients without TE around the same time. Finally, we enrolled 31 patients (M:F = 22:9; mean age, 62.97). We compared LS values from SE-EPI and GRE sequences by paired t-test and evaluated correlation co-efficient between LS values obtained by MRE and TE, respectively. In addition, we assessed and compared technical failure rates and areas of confidence for MRE measurements between two sequences.RESULTS: LS values from SE-EPI and GRE MRE were not significantly different (p = 0.13). LS values from two MRE sequences were significantly correlated with TE’s in statistically (SE-EPI; r = 0.76, p < 0.001 vs. GRE; r = 0.71, p < 0.001). There was no technical failure in SE-EPI MRE. In contrary, there were 4 technical failures in GRE MRE in the same study population. In addition, the areas of confidence for MRE measurements were significantly larger in SE-EPI than those of GRE MRE (p < 0.001).CONCLUSION: SE-EPI MRE is technically stable, and LS values obtained by this sequence would be reliable.

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SS 05 AB-06 11:00 Experimental implications in gadoxetic acid MRI enhancement and chemotherapeutic agent treatment responseHonsoul Kim1, Hye Jin Choi2 1Samsung Medical Center, 2Severance Hospital, Korea. [email protected]

PURPOSE: A subgroup of hepatocellular carcinoma (HCC) express organic anion transporting polypeptide (OATP) which results in tumor enhancement on the hepatobiliary phase of gadoxetic acid enhanced MRI. The purpose of this study was to elucidate the in vitro biological influence of tumor OATP expression in regard with treatment response of chemotherapeutic agents.MATERIALS AND METHODS: We transfected HEK 293 cells (which are non-hepatocyte origin) with human form OATP 1B3 cDNA attached to CMV promoter (pCMV-hOATP1B3) to serve as an in vitro cell platform simulating OATP expressing but mutidrug resistant protein (MRP)-2 non-expressing tumor cells. For comparison we used HEK 293 cells transfected with a blank plasmid containing only CMV promoter (pCMV-blank). Gadoxetic acid (1.2 ul/g) enhanced MRI (9.4T) of xenografts in nude mice produced by these cells were performed. Various concentrations of methotrexate were added into media during in vitro culture and MTT assay was performed to check the treatment response.RESULTS: Confocal microscopy revealed that only pCMV-hOATP1B3 transfected HEK 293 cells produced abundant OATP1B3 protein. Gadoxetic acid enhanced MRI of only pCMV-OATP1B3 transfected HEK 293 xenografts showed delayed contrast enhancement indicating the cellular uptake of gadoxetic acid by OATP1B3 protein. MTT assay revealed inferior cell viability of HEK 293 cells transfected with pCMV-hOATP1B3 compared to that of control (pCMV-blank).CONCLUSION: Tumor OATP1B3 express ion can enhance the in vitro treatment response of methotrexate. This implies that tumor hepatobiliary phase enhancement on gadoxetic acid enhanced MRI may potentially serve as a surrogate marker to predict the sensitivity of chemotherapeutic agents.

SS 05 AB-07 11:10Differentiation between focal nodular hyperplasia and hepatocellular adenoma: value of discrepancy in central scar between dynamic CT and gadoxetate disodium-enhanced MRHyo Jung Park, Jae Ho Byun, Ji Hun Kang, So Jung Lee, So Yeon Kim, Hyung Jin Won, Yong Moon Shin, Pyo Nyun Kim Asan Medical Center, Korea. [email protected]

PURPOSE: To identify the value of discrepancy in visibility or size of central scar (CS) between dynamic CT and hepatobiliary phase (HBP) image of gadoxetate disodium-enhanced MRI in differentiating focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA).MATERIALS AND METHODS: We enrolled 113 consecutive patients with pathologically diagnosed FNH (80 FNHs in 79 patients [age, 38.5 ± 15.0 years; 39 men]) or HCA (37 HCAs in 34 patients [age, 38.0 ± 13.1 years; 11 men]) and both dynamic contrast-enhanced CT and gadoxetate disodium-enhanced MRI. CS was defined as a focal low signal intensity (SI) clearly distinguished from the surrounding non-scary tumor tissue on HBP image corresponding to the hyperintense area on T2-weighted image (WI) or hypovascular area on CT. CT and MRI findings of each lesion including the visibility and size of CS on CT and HBP image were assessed by two abdominal radiologists independently and in consensus. Multivariable analyses using logistic regression were conducted to explore the value of discrepancy in CS between CT and HBP image in differentiating FNH from HCA.RESULTS: Regarding non-scary tumor t issue, homogeneous arterial enhancement, focal high SI on T1-WI (representing hemorrhage), heterogeneity on T1- or T2-WI, low SI on HBP image, and presence of fat were significantly different between FNH and HCA (p < 0.001). Regarding CS, CS presence and discrepancy in CS visibility or size between CT and HBP image were significantly different between the two diseases (p < 0.001). Multivariable analyses revealed that the absence of low SI of non-scary tumor tissue on HBP image, presence of CS, and discrepancy in CS visibility or size between CT and HBP image were suggestive of FNH rather than HCA (p < 0.02). Area under the ROC curve yielded with and without the discrepancy in CS visibility or size between CT and HBP image was 0.918 (95% confidence intervals [CI], 0.853 to 0.982) and 0.957 (95% CI, 0,925 to 0.990), respectively.CONCLUSION: Discrepancy in CS visibility or size between dynamic CT and HBP image of gadoxetate disodium-enhanced MRI may enhance the differentiation of FNH from HCA.

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Diagnosis of HCC

Chairperson(s)Myeong-Jin Kim Severance Hospital, KoreaYoung Kon Kim Samsung Medical Center, Korea

SS 19 AB-01 08:00 Ancillary features in LI-RADS version 2018: a strategy to improve diagnosis of hepatocellular carcinoma ≤ 3 cmJi Hun Kang1, Sang Hyun Choi1, Dong Hwan Kim2,Jae Ho Byun1, So Jung Lee1, So Yeon Kim1, Hyung Jin Won1, Yong Moon Shin1, Pyo Nyun Kim1

1Asan Medical Center, 2The Catholic University of Korea, Seoul St. Mary’s Hospital, [email protected]

PURPOSE: The Liver Imaging Reporting and Data System (LI-RADS) contains various ancillary features (AFs), but the use of AFs is optional, and might be unclear. We aimed to determine the strength of association with hepatocellular carcinoma (HCC) ≤ 3 cm of each AF in LI-RADS version 2018, and to develop an appropriate strategy for applying AFs to improve diagnostic performance on gadoxetate-enhanced MRI.MATERIALS AND METHODS: A total of 385 nodules (283 HCCs, 18 non-HCC malignancies, and 84 benign nodules) of ≤ 3 cm in 266 patients at risk for HCC who underwent gadoxetate-enhanced MRI in 2016 were retrospectively evaluated. Two radiologists independently assigned a LI-RADS category to each nodule. The diagnostic odds ratio (DOR) of each AF was assessed. To improve the diagnostic performance for HCC, various criteria were developed based on the number of AFs favoring malignancy in general or HCC in particular. Generalized estimating equation models were used to compare the diagnostic performance of each criterion with that of the major features (MFs) only.RESULTS: All AFs favoring HCC in particular and malignancy in general were more common in HCC group than in non-HCC group. Of these AFs, hepatobiliary-phase hypointensity had the strongest association with HCC (DOR, 21.82; 95% confidence interval, 5.59-85.20). When we applied AFs in addition to MFs, the new criterion (with a number of AFs ≥ 4) had significantly higher sensitivity (80.6% vs. 70.0%; p < 0.001) than MFs only, without a significant lower specificity (85.3% vs. 90.2%; p = 0.060).CONCLUSION: The AFs varied in the strengths of association with HCC ≤ 3 cm. To improve the diagnostic performance for HCC ≤ 3 cm, a new criterion (AFs ≥ 4)

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in addition to MFs might be the best option.

SS 19 AB-02 08:10 Diagnostic performance of LR-M criteria and imaging spectrum of primary hepatic malignanciesSeung-seob Kim, Sunyoung Lee, Jin-Young Choi, Mi-Suk Park, Myeong-Jin Kim Severance Hospital, Korea. [email protected]

PURPOSE: To evaluate diagnostic performance of LR-M criteria for differentiating hepatocellular carcinoma (HCC), intrahepatic mass-forming cholangiocarcinoma (iCC), and combined hepatocellular-cholangiocarcinoma (cHCC-CC) and to compare the imaging features of each type.MATERIALS AND METHODS: In this retrospective, case-control study, 110 patients with surgically proven iCC (n = 67) and cHCC-CC (n = 43) between June 2013 and June 2018 were enrolled as a case group. Another 110 patients with size-matched HCC were selected as a control group. Two independent readers evaluated imaging findings of preoperative MRI based on LI-RADS version 2018 and assigned LI-RADS category without knowing postsurgical histopathology. Diagnostic performance of LR-M criteria was evaluated and imaging features of iCC, cHCC-CC, and HCC were compared.RESULTS: In the case group, 91 patients were categorized into LR-M and 15 patients into LR-5 (83% and 14%, respectively), while 13 patients of the control group were categorized into LR-M and 88 patients into LR-5 (12% and 80%, respectively). When more than two features of LR-M criteria were present, it suggested iCC or cHCC-CC with the specificity of 94.5%. Among the case group, findings of LI-RADS major criteria were more frequently seen in patients with cHCC-CC, while those of LR-M criteria were more prominent in those with iCC. Among the lesions with peripheral arterial phase hyperenhancement, enhancing rim was evenly uniform

in 38 patients with iCC (out of 52 patients, 73.1%), while 14 patients with cHCC-CC showed irregularly thickened area of enhancing rim (out of 25 patients, 56%; p = 0.022).CONCLUSION: Diagnostic performance of LR-M criteria is desirable, and combination of imaging features is helpful for differentiating LR-M from HCC. The presence of irregularly thickened area of enhancing rim may suggest cHCC-CC rather than iCC.CLINICAL RELEVANCE: The presence of more than two LR-M findings is highly suggestive of iCC or cHCC-CC. Combination of imaging features may be helpful for differentiating primary liver malignancies.

SS 19 AB-03 08:20Liver Imaging Reporting and Data System category 3 and 4 observations: categorization pathway as an indicator of risk of progressionYeun-Yoon Kim1, Jin-Young Choi2, Myeong-Jin Kim2 1Samsung Medical Center, 2Severance Hospital, Korea. [email protected]

PURPOSE: To investigate the risk of progression in Liver Imaging Reporting and Data System (LI-RADS) category 3 (LR-3) and 4 observations according to categorization pathway.MATERIALS AND METHODS: Among 277 treatment-naive patients with indeterminate focal liver lesions on gadolinium-enhanced MRI from 2014 to 2015 and chronic hepatitis B or liver cirrhosis, we recruited 84 patients who received histopathological confirmation of lesion or had at least one follow-up CT or MRI before locoregional treatment. A total of 113 observations

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were retrospectively categorized based on LI-RADS v2018, and the element among LI-RADS diagnostic table information, ancillary features, and tie-breaking rules which contributes to the categorization (i.e., categorization pathway) was identified. Pathology results and follow-up data were summarized according to the categorization pathway at baseline. Cumulative incidence curves for progression to malignancy (pathologic diagnosis or malignant LI-RADS category) were generated for each categorization pathway and compared using log-rank tests with a resampling extension.RESULTS: Of 51 LR-3 and 62 LR-4 observations, pathways were determined by the LI-RADS diagnostic table in 47 (92.2%) and 15 (24.2%), by ancillary features in 4 (7.8%) and 40 (64.5%), and by tie-breaking rules in 0 and 7 (11.3%) observations, respectively. The cumulative incidence of progression to malignancy was higher for LR-4 observations than for LR-3 observations (66.4% vs. 16.4% at 2 years; p < 0.001). Hypervascular LR-4 observations had a higher cumulative incidence of progression to malignancy than hypovascular, upgraded, or tie-breaking rule-based LR-4 or hypervascular LR-3 observations (100% vs. 40.3% at 1 year; p = 0.042), which had, in turn, a higher cumulative incidence than downgraded or hypovascular LR-3 observations (40.3% vs. 5.6% at 1 year; p = 0.003).CONCLUSION: The risk of progression can be stratified by several categorization pathways in LR-3 and LR-4 observations. Categorization pathways may be useful to suggest the risk of progression in indeterminate observations.

SS 19 AB-04 08:30LI-RADS categorization in patients with prior HCC using gadoxetic acid enhanced MRI: are LR4 observations enough for the diagnosis of HCC in patients with prior history of HCC treatment?Heesoo Kim, Joon-Il Choi, Dong Hwan Kim, Seo Yeon Youn, Sung Eun Rha The Catholic University of Korea, Seoul St. Mary’s Hospital, Korea. [email protected]

PURPOSE: The Liver Imaging Reporting and Data System (LI-RADS) can be applied to patients with prior history of hepatocellular carcinoma (HCC). They were evaluated with?the diagnostic performance of LI-RADS version 2018 using gadoxetic acid enhanced MRI.MATERIALS AND METHODS: 264 consecutive patients underwent liver transplantation or resection for HCC in our institute from May 2013 to April 2018. 66 patients had 1) gadoxetic acid enhanced MRI within one month before transplantation or resection, and 2)

medical history of prior treatment of HCC. We excluded 15 patients because they had 1) more than five HCCs, or 2) infiltrative HCC. A total of 51 patients (M:F = 40:11; mean age, 56.8 years) were included in the final study population. Two radiologists reviewed gadoxetic acid enhanced MRI and determined the presence of LR3, LR4, and LR5 observations except previously treated tumors, based on the LI-RADS version 2018 and by consensus. We evaluated the diagnostic performance of each LI-RADS category with pathologic diagnosis as reference standard.RESULTS: Sensitivities for viable HCC of LR5 and LR4+LR5 observations were 32.6% (14/43) and 81.4% (35/43), respectively. Positive predictive values (PPV) for viable HCC of LR5, LR4, and LR3 observations were 100% (14/14), 70.0% (21/30), and 37.5% (3/8), respectively. 100% (3/3) of LR4 observations determined by major features only (LR4n) were HCC. PPV of LR4

observations upgraded from LR3 using ancillary features (LR4u) was 66.7% (18/27). For LR4u observations, PPV of observations with arterial enhancement (LR4ua) and without arterial enhancement (LR4un) were 84.2% (16/19) and 25.0% (2/8), respectively (p = 0.0035). Sensitivities and PPV for LR5+LR4n+LR4ua observations were 76.7% (33/43) and 91.2% (33/36), respectively.CONCLUSION: Sensitivity of LR5 observations for detection of viable HCC using gadoxetic acid enhanced MRI in patients with prior history of HCC treatment was low. Regarding LR4 observations as HCC results in reduced PPV. Presuming LR4 observations with arterial enhancement as HCC may compromise both sensitivity and PPV.CLINICAL RELEVANCE/APPLICATION: In patients with prior history of HCC, risk of HCC development

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is very high, therefore generous diagnostic criteria for imaging diagnosis of HCC might be appropriate. We may consider LR4 observations with arterial enhancement as HCC, like LR5, in patients with prior HCC history.

SS 19 AB-05 08:40Retrospective validation of HCC diagnosis on Gd-EOB-MRI: comparison of portal venous and second portal venous phases for the determination of washout and for noninvasive diagnosis of HCCHyo-Jin Kang1, Jeong min Lee1, Sun Kyung Jeon1, Siwon Jang1, Joon Koo Han2

1Seoul National University Hospital, 2Seoul National University College of Medicine, Korea. [email protected]

PURPOSE: To retrospectively compare portal venous phase (PVP) and second PVP (PVP2) for detection of “washout” of hepatocellular carcinoma (HCC) at in patients with high risk for HCC and their diagnostic performance of for noninvasive diagnosis of HCC.MATERIALS AND METHODS: This retrospective study included 120 patients at high risk for HCC with 162 observations (HCCs, n = 124; non-HCC malignancies, n = 9; benign, n = 29) showing arterial phase hyper-enhancement (APHE) ≥ 1 cm on Gd-EOB-MRI. Two PVP image sets were consecutively acquired using a fat-suppressed 3D-gradient echo sequence (acquisition time: 15 secs), 10 seconds after acquisition of arterial phase imaging which was determined by real-time fluoroscopic monitoring of distal thoracic aorta after gadoxetic acid injection. Imaging diagnosis was made by consensus review of two radiologists using either PVP image sets or second PVP image sets according to the Liver Imaging Reporting and Data System (LI-RADS) v2018. LR-3, LR-4 or LR-5 categorization was made after excluding non-LR-1/2/M. Sensitivity, specificity, and area under the curve (AUC) values were compared using McNemar’s test.RESULTS: The mean time intervals from gadoxetic acid injection for the first and second PVP image acquisitions were 59 ± 2 sec and 91 ± 3 sec, respectively. The PVP2 image sets presented significantly high sensitivity (79.0%) than PVP image sets (48.4%, p < 0.01). The specificity of the PVP2 image set (86.8%) was also comparable to that of PVP image set (92.1%, p = 0.48). The diagnostic performance of HCC using the PVP2 image set (AUC, 0.86, respectively) was significantly higher than that of PVP image set (AUC, 0.68) (all ps < 0.01).CONCLUSION: For non-invasive diagnosis of HCC on Gd-EOB-MRI, the second PVP images could more sensitively detect “washout” of HCC and therefore,

enabled more accurate diagnosis of HCC than PVP according to LI-RADS v2018.

SS 19 AB-06 08:50Arterial subtraction images of gadoxetate-enhanced MRI improve diagnosis of early-stage hepatocellular carcinomaDong Hwan Kim1, Sang Hyun Choi2, Jae Ho Byun2, Ji Hun Kang2, Young-Suk Lim2, So Jung Lee2

1The Catholic University of Korea, Seoul St. Mary’s Hospital, 2Asan Medical Center, Korea. [email protected]

PURPOSE: Although gadoxetate disodium-enhanced magnetic resonance imaging (MRI) shows higher sensitivity for diagnosing hepatocellular carcinoma (HCC), its arterial-phase images may be unsatisfactory because of weak arterial enhancement. We investigated the clinical effectiveness of arterial subtraction images from gadoxetate disodium-enhanced MRI for diagnosing early-stage HCC using the Liver Imaging Reporting and Data System (LI-RADS) v2018.MATERIALS AND METHODS: A total of 372 hepatic nodules (273 HCCs, 18 other malignancies, and 81 benign nodules) of 3.0 cm or smaller from 258 patients at risk of HCC who underwent gadoxetate disodium-enhanced MRI in 2016 were retrospectively analyzed. Final diagnosis was assessed histopathologically or clinically (marginal recurrence after treatment or change in lesion size on follow-up imaging). The detection rate for arterial hyperenhancement was compared between ordinary arterial-phase and arterial subtraction images, and the benefit of arterial subtraction images in diagnosing HCC using LI-RADS was assessed.RESULTS: Arterial subtraction images had a significantly higher detection rate for arterial hyperenhancement than ordinary arterial-phase images, both for all hepatic nodules (72.3% vs. 62.4%, p < 0.001) and HCCs (91.9% vs. 80.6%, p < 0.001). Compared with ordinary arterial-phase images, arterial subtraction images significantly increased the sensitivity of LI-RADS category 5 for diagnosis of HCC (64.1% [173/270] vs. 55.9% [151/270], p < 0.001), without significantly decreasing specificity (92.9% [91/98] vs. 94.9% [93/98], p = 0.155). For histopathologically confirmed lesions, arterial subtraction images significantly increased sensitivity to 68.8% (128/186) from the 61.3% (114/186) of ordinary arterial-phase images (p < 0.001), with a minimal decrease in specificity to 84.8% (39/46) from 89.1% (41/46) (p = 0.151).CONCLUSION: Arter ial subtract ion images of gadoxetate disodium-enhanced MRI can significantly improve the sensitivity for diagnosing early-stage HCC, without a significant decrease in specificity, using LI-

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RADS.

SS 19 AB-07 09:00 Comparison of international guidelines for diagnosis of hepatocellular carcinoma using gadoxetic acid-enhanced MR imaging in patients undergoing liver transplantationSun Kyung Jeon1, Jeong Min Lee2, Ijin Joo1, Jinyoung Park3, Jeongin Yoo1, Joon Koo Han2 1Seoul National University Hospital, 2Seoul National University College of Medicine, 3Inje University Busan Paik Hospital, Korea. [email protected]

PURPOSE: To compare the diagnostic performance of various guidelines for diagnosis of hepatocellular carcinoma (HCC) using gadoxetic acid-enhanced liver MRI (Gd-EOB-MRI) in patients undergoing liver transplantation (LT).MATERIALS AND METHODS: In this retrospective study, eighty patients (with 119 HCCs and 36 non-HCCs) with Child-Pugh class A or B who underwent preoperat ive Gd-EOB-MRI and subsequent LT were included. Two radiologists evaluated hepatic observations independently according to various guidelines (American Association for the Study of Liver Disease (AASLD), European Association for the Study of the Liver (EASL), Asian Pacific Association for the Study of the Liver (APASL), and Korean Liver Cancer Association-National Cancer Center (KLCA-NCC) guidelines) and allocated patients according to the Milan criteria and United Network for Organ Sharing (UNOS) guidelines. Comparisons of per-lesion sensitivity, specificity, and accuracy of patient allocation between guidelines were performed using logistic regression with generalized estimating equations (GEE).RESULTS: Among guidelines, APASL and KLCA-NCC guidelines (74.8-76.5% and 63.0-68.9%) showed significantly higher sensitivities than AASLD and EASL guidelines (28.6-46.2% and 27.7-38.7%) in both reader 1 and 2 (all ps < 0.001). The specificity of APASL guideline was significantly lower than AASLD and EASL guidelines in reader 2 (66.7% vs. 97.2% and 97.2%, all ps = 0.008, respectively), while the specificity of KLCA-NCC guideline showed no significant difference compared to that of AASLD/EASL guidelines in both readers (83.3-88.9% vs. 94.4-97.2%/94.4-97.2%, all ps > 0.05). The accuracy of the Milan criteria was significantly higher in APASL and KLCA-NCC guidelines than AASLD and EASL guidelines in both readers (75.0-76.3% and 72.5-75.0% vs. 55.0-66.3% and 53.8-60.0%, all ps < 0.001, respectively).CONCLUSION: In liver transplantation candidates, KLCA-NCC and APSAL guidelines showed significantly

higher sensitivity for diagnosing HCCs and diagnostic accuracy for patient allocation based on the Milan criteria and UNOS guidelines. In addition, the specificity of KLCA-NCC guideline showed no significant difference compared to AASLD/EASL guidelines.

SS 19 AB-08 09:10 Prospective intraindividual comparison of CT, MRI with extracellular contrast and gadoxetic acid for diagnosis of HCCJi Hye Min1, Young Kon Kim1, Jeong Eun Lee2, Kyung Sook Shin2 1Samsung Medical Center, 2Chungnam National University Hospital, Korea. [email protected]

BACKGROUND: CT and MRI play key roles in the diagnostic strategy for HCC in at-risk patients. The relative performance of CT, MRI with extracellular contrast agents (ECA-MRI), and MRI with hepatobiliary agents (HBA-MRI) for diagnosis of hepatocellular carcinoma (HCC) is still uncertain.PURPOSE: To prospectively compare the diagnostic performance of CT, ECA-MRI, and HBA-MRI in the diagnosis of HCC using the Liver Imaging Reporting and Data System (LI-RADS) with pathological confirmation.MATERIALS AND METHODS: Between November 2016 and February 2019, we prospectively enrolled 125 participants (102 men, 23 women; mean age 55.3 ± 8.8 years) with chronic liver disease who underwent CT, ECA-MRI, and HBA-MRI within one month before surgery for initial hepatic nodules detected via ultrasound. Two radiologists evaluated the presence of major and ancillary HCC features and assigned LI-RADS categories (v2018) based on CT and MRI. We then compared the diagnostic performance for LR-5 for each modality alone and in combination.RESULTS: In total, 163 observations (124 HCCs, 13 non-HCC malignancies, and 26 benign lesions; mean size, 20.7 mm) were identified. ECA-MRI showed a higher rate of identifying arterial phase hyperenhancement (16.1% and 8.1%), washout (5.6% and 6.5%), and enhancing capsule (51.6% and 44.4%) compared with CT and HBA-MRI, respectively. ECA-MRI showed better sensitivity and accuracy (83.1% and 86.5%) than either CT (63.7% and 71.8%; all ps < 0.001) or HBA-MRI (69.4%, p = 0.004 and 76.1%, p = 0.007, respectively), while all imaging modalities achieved 97.4% specificity. When combining CT with ECA-MRI or HBA-MRI, sensitivity (89.5% and 83.1%) and accuracy (91.4% and 86.5%) were increased compared with CT alone (all ps < 0.001).CONCLUSION: ECA-MRI showed better sensitivity and accuracy than CT or HBA-MRI for the diagnosis

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of HCC with LI-RADS. We achieved better diagnostic performance when applying CT in combination with one of the two MRIs compared with CT alone.

SS 19 AB-09 09:20Updated 10-year outcomes of percutaneous radiofrequency ablation as first-line therapy for single hepatocellular carcinoma < 3 cmMin Woo Lee1, Danbee Kang2, Hyo-Keun Lim1, Juhee Cho2, Dong Hyun Sinn1, Tae Wook Kang1, Kyoung Doo Song1, Hyunchul Rhim1, Dong Ik Cha1, David S.K. Lu3 1Samsung Medical Center, Korea, 2SAIHST, Sungkyunkwan University, Korea, 3David Geffen School of Medicine at UCLA, USA. [email protected]

PURPOSE: Radiofrequency ablation (RFA) techniques and management of hepatocellular carcinoma (HCC) patients have continuously evolved. Therefore, outcomes of RFA for HCC during the last decade are expected to be better than before but has not been properly investigated. The purpose of this study was to evaluate the 10-year therapeutic outcomes of percutaneous RFA for single nodular HCC < 3 cm using a large longitudinal hospital registry and clinical factors associated with overall survival and local tumor progression (LTP).MATERIALS AND METHODS: A total of 467 newly diagnosed patients with single nodular HCC < 3 cm that underwent RFA as first-line therapy between January 2008 to December 2016 were analyzed. Overall survival and LTP were estimated using the Kaplan-Meier method. Cox regression and competing risks Cox regression analysis were performed to identify prognostic factors for overall survival and LTP, respectively.RESULTS: The 5- and 10-year overall survival rates after RFA were 83.7% and 74.2%, respectively. LTP (hazard ratio [HR], 2.03, 95% confidence interval [CI], 1.19-3.47) was one of the important factors for overall survival after RFA. The 5- and 10-year LTP rates after RFA were 20.4% and 25.1%, respectively. Periportal location (subdistribution HR, 2.29; 95% CI, 1.25-4.21), subphrenic location (2.25, 1.34-3.86), size ≥ 1.5- < 2.0 cm (1.88, 1.05-3.39), and size ≥ 2.0 cm (2.10, 1.14-3.86) were independent factors for LTP.CONCLUSION: Ten-year therapeutic outcomes of percutaneous RFA as first-line therapy were excellent for single HCC < 3 cm. LTP was an important prognostic factor for overall survival after RFA. Periportal and subphrenic location of HCCs and tumor size were predictors for LTP after RFA.


Imaging of diffuse liver disease

Chairperson(s)Jeong-Sik Yu Gangnam Severance Hospital, KoreaSang Soo Shin Chonnam National University Hospital,

Korea

SS 21 AB-01 09:50Deep learning for classification of liver cirrhosis based on radiology common data modelEunyoung Kwon, Sihyeong Noh, Chang won Jeong, Tae-hoon Kim, Dong Min Kang, Youe Ree Kim, Young Hwan Lee, Kwon-Ha Yoon Wonkwang University Hospital, Korea. [email protected]

BACKGROUND: We proposed Radiology CDM(R_CDM) to generate standardized medical image data-sets that support a variety of clinical studies. Based on this we collected 1512 data from abdominal images and built a standardized medical imaging database, which made it easy to create data-sets based on the desired conditions (disease, device, protocol, etc.). We performed deep-learning through these data sets and were able to obtain high accuracy and sensitivity from the classification of LC and Non-LC. The advanced GoogLeNet was used for deep running.EVALUATION: Figure 1 shows the flow chart of the process in which the data-set is constructed through the R_CDM. The R_CDM reads DICOM’s Tag information and stores it in the DB. When creating a data set, it can read DB information to configure data sets based on settings such as disease and shooting protocols. Figure 2 shows the screen of the data-set as a result of the data set configuration process. Users can receive data by specifying DICOM files, image files, etc. And the patient's personal information is fully anonymous. Figure 3 is the algorithm used for deep learning, which is a modified algorithm based on GoogLeNet. The model of inception v3 was used. Figure 4 shows the set of LC and Non-LC data configured for deep learning. The LC had 118 case, with 40,575 images, while the Non-LC had 122 case, with 33,565 images being used.DISCUSSION: Figure 5 shows that as a result of deep learning the result is that Accuracy is about 99% and Loss is about 0.001%. We were able to achieve very good results for Validation as shown in Figure 6, for Accuracy 0.99292, Error Rate 0.00708 and Sensitivity LC = 0.99469 and Non-LC = 0.99115 respectively. Figure 7 shows that the algorithms in this paper perform better with the original GoogLeNet.

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CONCLUSION: Our proposed R_CDM has shown the potential for use through artificial intelligence clinical research in complying with international standards and providing customized data sets to the needs of consumers. It will spur the study of various forms of medical imaging data and help researchers achieve better results.

Fig. 1.

Fig. 2.

Fig. 3.

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Fig. 5.

Fig. 6.

Fig. 7.

SS 21 AB-02 10:00 Extracellular volume quantification of liver using dual-energy CT: utility for prediction of liver-related events in cirrhosisSeongjun Bak1, Ji Eun Kim1, Kyungsoo Bae2, Hocheol Choi1, Hyun Ok Kim1 1Gyeonsang National University Hospital, 2Gyeongsang National University Changwon Hospital, [email protected]

PURPOSE: To determine whether quantification of liver extracellular volume fraction (fECV) using dual-energy CT allows prediction of liver-related events (LRE) in patients with cirrhosis.MATERIALS AND METHODS: This retrospective study included 305 patients with cirrhosis who underwent dual source dual-energy liver CT and had serum markers within 2 weeks of initial CT imaging. The fECV score was measured using iodine map of equilibrium phase images obtained 3 minutes after contrast injection at 100 kVp and Sn140 kVp. Association of fECV score and serum markers with LRE was investigated. A risk model combining fECV score (< 27 or ≥ 27%) and albumin level (< 4 or ≥ 4 g/dL) was constructed for predicting LRE.RESULTS: Increased fECV score (odds ratio, 1.27; 95% confidence interval [CI], 1.15, 1.40) was independently associated with decompensated cirrhosis at baseline (n = 85) along with Model for End Stage Liver Disease score (odds ratio, 1.32; 95% CI, 1.07, 1.63). In patients with compensated cirrhosis, 10.5% (23 of 220) experienced LRE during a median follow-up period of 2.0 years (decompensation, n = 14; hepatocellular carcinoma, n = 9). fECV score (hazard ratio, 1.40; 95% CI, 1.22, 1.62) and albumin level (hazard ratio, 0.26; 95% CI, 0.09, 0.73) were independently predictive of LRE. Mean times to LRE in patients at high (16.5 months, n = 18), intermediate (25.6 months, n = 44), and low (30.5 months, n = 158) risk of LRE were significantly different (p < 0.0001).CONCLUSION: The fECV score derived from dual-energy CT images allows prediction of LRE in patients with cirrhosis.CLINICAL RELEVANCE/APPLICATION: The fECV score derived from iodine map of dual-energy CT can predict?LRE in cirrhotic patients. Dual-energy scanning is recommended as a part of liver CT during the follow-up of cirrhotic patients because it can provide prognostic indicator for LRE development.

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SS 21 AB-03 10:10Feasibility of CT texture analysis of hepatic fibrosis using dual-energy spectral detector CTByuk gyung Choi, In young Choi, Sang Hoon Cha, Suk Keu Yeom, Jaehyung Cha, Seung hwa Lee, Hwan Hoon Chung Korea University Ansan Hospital, Korea. [email protected]

PURPOSE: To evaluate the feasibility of CT texture analysis (CTTA) of liver using spectral CT for assessing hepatic fibrosis severity.MATERIALS AND METHODS: Eighty-seven patients who underwent liver dynamic CT on a spectral CT machine and had a reference standard for the diagnosis of liver fibrosis (histopathologic findings [n = 61] or clinical findings for normal [n = 26]) were included in our study. Single-slice images of liver were obtained with each 50 keV-, 60 keV-, 70 keV-, 80 keV-, and 90 keV- energy level. Mean gray-level intensity, mean of positive pixels (MPP), entropy, skewness, and kurtosis of CT texture analysis (CTTA) parameters on spatial scaling factor (SSF), 2-6, using commercially available software (TexRAD) were compared according to severity of liver fibrosis. Optimal CTTA parameters cutoffs to diagnose clinically significant fibrosis (stage F2-F4), advanced fibrosis (stage F3-F4), and cirrhosis (stage F4) were evaluated by receiver operating characteristic curve analysis. The CTTA parameters on different energy level images were correlated with the severity of liver fibrosis. The differences of CTTA parameters according to energy level were evaluated.RESULTS: For diagnosing staging F2-F4, entropy and mean gray-level intensity at low keV level showed the largest area under the curve (AUC) (0.79 and 0.79), respectively. For staging F3-F4, skewness at high keV level showed the largest AUC (0.78). For staging F4, kurtosis at low keV level showed the largest AUC (0.79). Mean gray intensity level at 50 keV level had a significant positive correlation with the stage of liver fibrosis (r = 0.502, p < 0.001). Kurtosis at 50 keV level has a significant positive correlation with the stage of liver fibrosis (r = 0.432, p < 0.001). Entropy at 50 keV level shows a significant negative correlation with the stage of liver fibrosis (r = 0.423, p < 0.001). Mean gray-level intensity and entropy showed the significant differences according to the different energy levels (p = 0.005, p < 0.001).CONCLUSION: Texture analysis using different energy level CT may be useful for assessing severity of liver fibrosis.CLINICAL RELEVANCE/APPLICATION: Comparable or higher iodine CNR can be achieved in the recently introduced monoenergetic imaging techniques. This study is the first study using different energy level CTs

for assessing liver fibrosis. The lower energy level CT could be helpful for assessing liver fibrosis CT compared with the single-energy scan at optimal kVp.

SS 21 AB-04 10:20 Quantitative measurement of hepatic fibrosis on gadoxetic acid - enhanced MRI in patients with chronic liver disease: multicenter studyYoue Ree Kim1, Young Hwan Lee1, Dong Min Kang1, Tae-hoon Kim1, Kyung Won Kim2, Yong Yeon Jeong3, Kwon-Ha Yoon1 1Wonkwang University Hospital, 2Asan Medical Center, 3Chonnam National University Hwasun Hospital, Korea. [email protected]

PURPOSE: To compare coefficient of variation (CV) in MR hepatobiliary image and serum biomarkers such as aspartate aminotransferase to platelet ratio index (APRI) and fibrosis-4 index (FIB-4) values according to the histopathologic fibrosis score, to identify the diagnostic performance of CV map in diagnosing hepatic fibrosis and to assess measurement reliability.MATERIALS AND METHODS: This study was a prospective multicenter study which included 71 patients who underwent 3-T or 1.5-T liver MR imaging using gadolinium EOB-DTPA and liver biopsy or surgery. Patients were divided into 4 groups according to the liver fibrosis score; Group 1 (F0, 1), Group 2 (F2), Group 3 (F3), Group 4 (F4). To quantitatively measure the hepatic fibrosis, MR hepatobiliary image was analyzed to identify inhomogeneous signal intensities calculated from CV map in the liver parenchyma. We also evaluated the comparison study of among CV, APRI and FIB-4. The diagnostic performance of the CV map for significant fibrosis (≧ F2), advanced fibrosis (≧ F3) and cirrhosis was evaluated using receiver operating characteristic (ROC) curve. Intra and interobserver agreement of CV measurement was analyzed.RESULTS: Mean CV values in each group were Group 1 (n = 19): 3.53 ± 0.30, Group 2 (n = 5): 4.20 ± 0.96, Group 3 (n = 21): 4.39 ± 0.80, and Group 4 (n = 26): 5.24 ± 1.15, respectively (p = 0.000). Mean FIB-4 values were Group 1: 1.21 ± 1.17, Group 2: 3.13 ± 2.96, Group 3: 3.52 ± 3.22, and Group 4: 4.84 ± 3.55, respectively (p

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= 0.002). APRI didn’t show statistical significance among each group (p = 0.271). Area under curves of CV values on ROC analysis were 0.891 for significant fibrosis, 0.839 for advanced fibrosis and 0.815 for cirrhosis (p = 0.000, respectively). Intra and Interobserver agreement of CV map measurement were 0.993 and 0.834. CONCLUSION: CV value based on hepatobiliary MR image provides accurate discrimination of hepatic fibrosis with reliable measurements and demonstrates high diagnostic performance.

SS 21 AB-05 10:30Double low dose dual-energy liver CT in patients at high-risk of HCC: a prospective, randomized, single-center studyJeong Hee Yoon1, Won Chang2, Eun Sun Lee3, Sang Min Lee4, Jeong Min Lee5 1Seoul National University Hospital, 2Seoul National University Bundang Hospital, 3Chung-Ang University Hospital, 4Hallym University Sacred Heart Hospital, 5Seoul National University College of Medicine, [email protected]

PURPOSE: To investigate the clinical feasibility of the simultaneous reduction of radiation and contrast doses using spectral CT in patients at high-risk for hepatocellular carcinoma (HCC).MATERIALS AND METHODS: Between May 2017 and March 2018, this prospective study recruited participants at risk of HCC with body mass indexes < 30 and randomly assigned them to either the standard-dose group or the double low-dose group which targeted 30% reductions in both radiation and contrast media. Lesion conspicuity as a primary endpoint, and lesion detection rates were then compared between standard-dose filtered back projection (FBP) and double low-dose 50 keV images. Participants and reviewers were blinded for scan protocols and reconstruction algorithms. Lesion conspicuity was analyzed using generalized estimating equation analysis.RESULTS: Sixty-seven participants (M:F = 59:8; mean age, 64 ± 9 years) were analyzed. Compared with the standard-dose group (n = 32), significantly lower CTDIvol (8.8 ± 1.7 mGy vs. 6.1 ± 0.6 mGy) and contrast media (116.9 ± 15.7 ml vs. 83.1 ± 9.9 ml) were utilized in the double low-dose group (n = 35) (p < 0.001). Comparative analysis demonstrated that, lesion conspicuity were significantly higher on double low-dose 50 keV images than on standard dose FBP images on both arterial (2.62 [95% CI: 2.31, 2.93] vs. 1.83 [95% CI: 1.56, 2.11], respectively, p < 0.001) and portal venous phases (2.39 [95% CI: 2.11, 2.67] vs. 1.80 [95% CI: 1.57, 2.02], respectively, p = 0.001). No differences in lesion detection capability were observed between the two

groups (figure of merit: 0.62, standard-dose FBP; 0.65, double low-dose 50 keV; p = 0.38).CONCLUSION: Low monoenergetic spectral CT images (50 keV) can provide better focal liver lesion conspicuity than standard-dose FBP in non-obese patients while using lower radiation and contrast media doses

SS 21 AB-06 10:40Spleen shear wave elastography: a non-invasive tool for prediction and grading of esophageal varicesJuhi Agrawal, Amita Malik, Neha Antil, Maninder KaurVMMC & Safdarjung Hospital, New Delhi, India. [email protected]

PURPOSE: Cirrhosis of liver and portal hypertension are one of the common causes of morbidity around the world. Esophageal varices develop in two-thirds of the patients suffering from cirrhosis, with 30% of them resulting in upper GI bleed. Immediate deaths from uncontrolled bleeding account for 4-8% of the cases. Upper GI endoscopy (UGIE) is a gold standard tool for detection of esophageal varices, but is invasive and has poor patient compliance. Therefore, it is crucial to have an alternative promising non-invasive tool. Our study aims to correlate splenic shear wave elastography (SWE) with endoscopy to predict and grade EVs.MATERIALS AND METHODS: Sixty patients diagnosed with cirrhosis and portal hypertension were included in the study after excluding children < 18 years, patients with HCC, NCPF and co-existing cardiac/renal conditions. Splenic SWE and UGIE were performed in all patients. Splenic SWE was also performed after placing region of interest at upper, inter-pole and lower pole of spleen. The average of three values was calculated and used as final measure. Splenic SWE was compared and correlated with endoscopy results.RESULTS: Splenic SWE proved quite significant (p < 0.0001) in predicting presence of EVs. The area under curve (AUC) and sensitivity of splenic stiffness was 0.992 and 93.8% respectively. The splenic stiffness cut off value for predicting esophageal varices was 6.6 kPa with sensitivity and specificity of 93.88% and 100% respectively. Splenic SWE also proved significant for grading of varices (p < 0.0001), confirmed at endoscopy. Mean splenic stiffness score for F1 varices was 8.71 ± 1.78 kPa, for F2 varices was 16.52 ± 4.96 kPa and for F3 was 38.27 ± 13.28 kPa, where F1, F2, F3 correspond to grading of esophageal varices on endoscopy according to the BEPPU classification.CONCLUSION: Splenic SWE can serve as a non-invasive alternative tool to UGIE in predicting and grading EVs, since the study showed high sensitivity (93.88%) and specificity (100%).

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CLINICAL RELEVANCE/APPLICATION: Splenic SWE has an excellent predictive accuracy to foresee esophageal varices which aids in timely intervention and thus prevents the risk of life-threatening variceal hemorrhage.

SS 21 AB-07 10:50 Impact of shear wave elastography techniques, respiratory speeds, and measuring methods on liver fibrosis evaluation: a phantom studyHaerang Jung, Sang Min Lee, Min-Jeong Kim, Hong-Il Ha, Kwanseop Lee Hallym University Sacred Heart Hospital, Korea. [email protected]

PURPOSE: To determine whether applicabi l i ty rate, elasticity values, and measurement time differ depending on shear wave elastography (SWE) techniques (point SWE vs. 2 dimensional [2D]-SWE), respiratory speed, and region-of-interest (ROI) method using a liver phantom experiment.MATERIALS AND METHODS: The elasticity values were measured by three operators using four elasticity phantoms with different elasticity values, with two types of SWE (pSWE and 2D-SWE), three respiratory modes (static mode and low/ high speed of moving mode), and four ROI methods of 2D-SWE (circle ROI, point ROI, entire ROI, and multiple ROIs including 2 or 3 circle ROIs). Each exam consisted of 10 elasticity values measurements. Applicability rate (ratio of exams without unreliable measurement and technical failure) was compared using Fisher’s exact test. The elasticity values and measurement time were compared using Wilcoxon test and Kruskal-Wallis test. Intra- or inter-observer variability was evaluated using intraclass correlation (ICC).RESULTS: The applicability rate of 2D-SWE with one circular ROI (c2D-SWE) were significantly higher than that of pSWE (97.2% [35/36] vs. 63.9% [23/36], p < 0.001). In low speed and high speed of moving modes, applicability rates were more decreased when using pSWE compared with c2D-SWE (41.7% [5/12] and 50.0% [6/12] vs. 100% [12/12] and 91.7% [11/12]). The elasticity values were significantly different between pSWE and c2D-SWE (p = 0.006). However, there was no significant difference in mean elasticity values according to ROI methods on 2D-SWE (p = 0.592). There was considerable difference in measurement time among four ROI methods of 2D-SWE (p < 0.001). On post hoc analysis, measurement time in multiple ROI method was significantly shorter than that in circular ROI method (46.7 sec vs. 177.2 sec, p < 0.001). ICCs for intra-or inter-observer variability were excellent in pSWE and 2D-SWE with all methods ROIs.

CONCLUSION: Compared with pSWE, 2D-SWE could be more feasible in evaluating liver fibrosis evaluation even at high respiratory speed. Further, 2D-SWE with multiple ROIs could enable fast measurement without change of elasticity value

SS 21 AB-08 11:00Electrical conductivity based tissue contrast MR imaging for evaluating liver fibrosis: in vivo animal feasibility studyJin Woong Kim1, Hyung Joong Kim2 1College of Medicine, Chosun University, 2Kyung Hee University, Korea. [email protected]

PURPOSE: To evaluate the clinical feasibility of magnetic resonance (MR)-based electrical conductivity imaging method which can provide novel contrast in format ion on t issue condi t ion based on the concentration and mobility of ions in liver fibrosis.MATERIALS AND METHODS: L ive r f i b ros i s was induced by an intraperi toneal inject ion of dimethylnitrosamine in rat model. After induction, four electrodes were attached on the abdomen and rats were placed inside the bore of 3T MRI scanner. Using a current source, we injected a current of amplitude 1 mA and a pulse width of 81 msec. A multi-spin-echo ICNE pulse sequence was used to obtain the magnetic flux density (Bz) data and the imaging parameters were as follows: TR/TE 1000/15 ms (5 echoes), FOV 60´60 mm2, matrix size 128´128, slice thickness 3 mm, NEX 4, and a total imaging time 30 min. After imaging experiment, we applied the projected current density algorithm for multi-slice conductivity image reconstructions. We sacrificed the rats and obtained the liver tissue samples for the immunohistochemical examination to prove our model.RESULTS: All liver tissues showed uniform conductivity contrast before induction of fibrosis. After induction, there was a regional difference in the conductivity contrast depending on the degree of fibrosis. The fibrous region, over 5 weeks after induction, showed conductivity increase more than 12% compared to the same regions before induction. In comparison of liver regions after induction, fibrous region showed conductivity increase more than 11% compared to the opposite normal region over 5 weeks after induction. Liver samples represent tissue damages such as color, stiffness, and volume reduction from the histological findings.CONCLUSION: The electrical conductivity based contrast MR imaging method was performed to investigate any tissue changes before and after induction of liver fibrosis. The conductivity images shown in this study indicated that time-course variations of conductivity contrast between normal and fibrous

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regions are distinguishable in a different way which is based on the concentration and mobility changes of ions in liver tissues.

SS 21 AB-09 11:10Contrast enhanced ultrasound is a useful imaging test in patients with Budd Chiari syndromePankaj Gupta, Suzanne Koshi, Saroj Kant Sinha, Harshal Mandavdhare, Vishal Sharma, Jayanta Samanta, Usha Dutta, Rakesh KoccharPost Graduate Institute of Medical Education and Research, India. [email protected]

PURPOSE: To investigate the role of contrast enhanced ultrasound (CEUS) in diagnosis of Budd Chiari syndrome (BCS).MATERIALS AND METHODS: This was a retrospective study of patients with suspicion of BCS who underwent CEUS of the hepatic veins (HVs) and inferior vena cava (IVC) between July 2017 and April 2019. CEUS was performed using Sonovue®. All patients underwent Doppler evaluation of the HVs and IVC. Additionally, computed tomography (CT) and/or magnetic resonance venography (MRV) were performed on the discretion of the referring gastroenterologist. The final diagnosis of BCS was based on transvenous or percutaneous digital subtraction venography (DSV). Following findings were recorded on each imaging modality-level of block (HVs/ IVC/ both), total number of veins involved, intrahepatic veno-venous collaterals and focal liver lesions. The diagnostic accuracy of CEUS was compared with Doppler, CT and MRV.RESULTS: A total of 19 patients (median age, 30 years; 11 males) were evaluated with CEUS and Doppler. CT, and MRV were performed in 10, and 6 patients respectively. A final diagnosis of BCS was established on DSV in 15 patients. CEUS was found to have a 100% sensitivity and 75% specificity. The sensitivities of Doppler, CT and MRV were 100%, 100% and 90% respectively. Doppler had a lower specificity of 25%. The diagnostic accuracy of CEUS was the highest (94.74%) followed by that of CT (90%), Doppler (84.29%) and MRV (66.67%).CONCLUSION: CEUS is a useful adjunct to the available imaging modalities in the diagnosis of BCS.


New techniques of Abdominal Imaging and Pancreas

Chairperson(s)Jung Hoon Kim Seoul National University Hospital,

KoreaJoon-Il Choi The Catholic University of Korea, Seoul

St. Mary's Hospital, Korea

SS 26 AB-01 16:00 Development and validation of a deep learning-based algorithm for detecting malignant hepatic lesions on multi-phase CT in patients at high risk for hepatocellular carcinomaDong Wook Kim1, So Yeon Kim1, Gaeun Lee1, Geunhwi Ahn1, June-Goo Lee1, Seung Soo Lee1, Kyung Won Kim1, Seong Ho Park1, Yoon Jin Lee2, Namkug Kim1 1Asan Medical Center, 2Seoul National University Bundang Hospital, Korea. [email protected]

PURPOSE: To develop and validate a deep-learning model for automatic detection of malignant hepatic lesions on multi-phase CT in patients at high risk?for hepatocellular carcinoma (HCC).MATERIALS AND METHODS: In this retrospective study, 1350 multi-phase CT image series including pre-, arterial-, portal-, and delayed-phases in 1320 patients at high risk for HCC (M:F = 1054:296; mean age, 56.76 years; age range, 20-87 years) obtained between 2007 and 2016 were included. Focal hepatic lesions were labeled and annotated by five board-certified radiologists. Final diagnosis of focal hepatic lesions was confirmed either by pathologic results for suspicious malignant lesions or by follow-up imaging studies for benign lesions. The CT images were randomly split into a development set (761 CT series) and a validation set (589 CT series). The development set was further divided into 568 CT scans for training the deep learning based malignant hepatic lesion detection model and 193 CT scans for finding the operational parameter by using the jackknife alternative free-response receiver-operating characteristic (JAFROC) figure of merit (FOM) for per-lesion-based analysis. Diagnostic performances of the developed model were tested in the validation set as sensitivity and false positive (FP) rate per case.RESULTS: A total of 1348 focal hepatic lesions (462 benign lesions and 886 malignant nodules including 825 HCCs and 61 non-HCC malignancies) in the

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development set and 809 focal hepatic lesions (415 benign lesions and 394 malignant nodules including 377 HCCs and 17 non-HCC malignancies) in the validation set were labeled. The operational parameter was selected by the JAFROC FOM and applying less than 3 FPs criteria. The detection performance of malignant hepatic lesions was 89% of sensitivity and 2.54 FP rate in the validation set.CONCLUSION: The deep learning-based system showed high diagnostic performance for detecting malignant hepatic lesions.CLINICAL RELEVANCE: Deep-learning based detec-tion system has potential to be a promising tool to help radiologists to accurately detect focal hepatic malignancies on multi-phase CT.

SS 26 AB-02 16:10 Fully automatic deep-learning system to select L3 slice and measure abdominal muscle area on CT Jiyeon Ha, Kyung Won Kim, Yousun Ko Asan Medical Center, Korea. [email protected]

PURPOSE: The sarcopenia researches have been expanding rapidly. The case numbers requiring abdominal muscle measurement in each research have also been rapidly increasing, requiring human resources and time. One of the big hurdles to automate such measurement process is to select L3 vertebrae level. We aim to develop and validate a fully automatic system to select L3 level and measure muscle mass.MATERIALS AND METHODS: A residual learning-based deep learning model (DLM) was developed by supervised learning from a training data set (500 CT scans). A residual network with 50 layers was adopted for developing deep learning system. A radiologist provided L3 slice level as the ground truth. The developed DLM automatically spotted the CT slice of L3 inferior endplate level. In the validation data set (n = 500), validation was done at 496 CT scans after excluding four patient CT scans who underwent lumbar interbody fusion surgery. The difference in millimeter between the ground truth and DLM-derived CT slice was calculated by multiplying slice thickness and the difference of CT slice number between the ground truth and DLM-derived CT slice. Technical success was evaluated based on 10 mm cut-off value in the slice difference. Subgroup analysis was performed according to the vertebral anatomic variation.RESULTS: The mean differences between ground truth and DLM-derived slice were 3.6 mm ± 8.3 in whole validation set (n = 496), 2.5 mm ± 6.1 in subgroup with normal anatomy (n = 438), and 12.1 mm ± 15.1 in subgroup with anatomic variation (n = 58). Technical success rates were 93.3% (463/496) in whole validation set, 96.3% (422/438) in subgroup with normal anatomy, and 67.2% (39/58) in subgroup with anatomic variation.CONCLUSION: The residual network-based DLM system exhibited a high performance in the automatic selection of L3 inferior endplate level, which enables fully automated measurement of abdominal muscle area on CT.

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CLINICAL RELEVANCE/APPLICATION: Fully-auto-matic L3 level spotting system can be used to identify optimal CT slice for body composition segmentation in a consistent manner.

SS 26 AB-03 16:20 Dual-layer spectral CT of pancreatic adenocarcinoma: can virtual monoenergetic imaging of portal venous phase replace pancreatic phase?Beom Jin Park, Yeo eun Han, Min Ju Kim, Nayeon Han, Ki Choon Sim, Deuk Jae Sung Korea University Anam Hospital, Korea. [email protected]

PURPOSE: To evaluate diagnostic performance and optimal keV of virtual monoenergetic imaging (VMI) created from portal venous phase in comparison with conventional 120 kVp polychromatic imaging of pancreatic phase on dual- layer spectral CT when assessing pancreatic adenocarcinoma and peripancreatic vasculature.MATERIALS AND METHODS: In this retrospective study, thirty patients with pancreatic adenocarcinoma who underwent dual-layer spectral CT scan with nonenhanced images, pancreatic phase, and portal venous phase were included. VMIs for 40 keV (VMI40), 55 keV (VMI55), and 70 keV (VMI70) of portal venous phase were created, and each VMI was compared with conventional 120 kVp polychromatic imaging of pancreatic phase. In all four images, tumor-to-pancreas contrast-to-noise ratio (CNR) and attenuation difference were compared for tumor conspicuity. CNR and signal-to-noise ratio (SNR) of the celiac trunk, superior mesenteric artery, portal vein, and superior mesenteric vein were compared for peripancreatic vasculature

assessment. Effective radiation dose for standard triple-phase and dual-phase without pancreatic phase CT scan were compared.RESULTS: VMI40 of portal venous phase demonstrated significantly the greatest (p < 0.001) tumor-to-pancreas CNR and attenuation difference, peripancreatic vascular CNR and SNR than those of conventional pancreatic phase and VMI55, VMI70 of portal venous phase. VMI55 of portal venous phase demonstrated second greatest (p < 0.001) results in all measured values. VMI70 of portal phase and conventional pancreatic phase were equivalent in tumor-to-pancreas attenuation difference and CNR of arteries (celiac trunk and superior mesenteric artery). Mean effective dose was 12.8 ± 3.9 mSv and 8.9 ± 2.7 mSv for standard triple-phase CT scan and dual-phase CT scan without pancreatic phase, respectively.CONCLUSION: For assessing pancreatic adenocarcino-ma, VMI40 of portal venous phase obtained on dual-layer spectral CT demonstrated superior tumor conspicuity, higher CNR and SNR for peripancreatic vasculature than those of conventional pancreatic phase.CLINICAL RELEVANCE/APPLICATION: VMI40 of portal venous phase may replace conventional pancreatic phase with better diagnostic performance and reduced radiation dose. Further study in greater population may be required.

SS 26 AB-04 16:30 Comparison and correlation of attenuation values on virtual and true non-contrast images obtained by triphasic dynamic series with third-generation dual-source dual-energy CTSung min Kim, Taeyoung Lee, Byeong Seong Kang, Woon Jung Kwon, Minseo Bang, Soyeoun Lim, Gyeong Min Park Ulsan University Hospital, Korea. [email protected]

PURPOSE: To evaluate the agreement and correlation between the true non-contrast attenuation values of intra-abdominal structures and attenuation values obtained on virtual non-contrast images based on dual source dual-energy CT in arterial, portal and delay phase. The agreement and correlation of calcified plaque volume obtained on virtual non-contrast images based on dual source dual-energy CT were also evaluated.MATERIALS AND METHODS: Seventy-seven patients who underwent triphasic abdominal CT (liver dynamic protocol) between November 2018 and January 2019 were retrospectively reviewed. Unenhanced series was performed using conventional single-energy mode at 120 kVp. Arterial, venous phase and 5 minutes delayed

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phase post-contrast series were obtained utilizing dual source dual-energy CT technique (tube potential, 90 kVp and Sn 150 kVp). Virtual non-contrast images were processed off of arterial (VNC-art), venous phase (VNC-por) and 5 minutes delayed (VNC-del) series. Attenuation values of liver, pancreas, kidneys, muscle, subcutaneous fat intra-abdominal fat, vertebra, aorta, IVC, main portal vein, intrahepatic portal vein and abdominal aortic calcification volumes were recorded on true non-contrast study and virtual non-contrast study sets of images. Attenuation values of liver, pancreas, vertebra and back muscle obtained from VNC images were adjusted by using simple linear regression.RESULTS: Paired t test showed significant difference between TNC, VNC-art, VNC-por and VNC-del attenuation across all organs (p < 0.0001). But there were excellent correlations between TNC and VNC attenuation values of liver (R2 = 0.89-0.92), pancreas (R2 = 0.60-0.72), spleen (R2 = 0.45-0.64), back muscle (R2 = 0.61-0.64), vertebra (R2 = 0.84-0.88), subcutaneous fat (R2 = 0.89-0.92) and visceral fat (R2 = 0.89-0.92). The Bland-Altman plots shown various degrees of bias and limit of agreement between the attenuation of each tissue obtained from the TNC and VNC. The values estimated by regression equations offers a better approximation of the values obtained from TNC and especially it was effective when the attenuation values of vertebra obtained from the VNC image were corrected.CONCLUSION: Although the attenuation values of all tissues were significantly different between virtual non-contrast and true non-contrast images, the correlation values were excellent. And estimated regression equations were useful for predicting the values obtained from TNC. Further optimization of post-processing algorithms might be necessary before complete replacement of TNC with VNC images.

SS 26 AB-05 16:40 Pilot study of unsupervised automatic detection of multiple traumatic body lesionsYura Ahn, Gil-Sun Hong, Hyun-jin Bae, Sungwon Park, Won-jung Chung, Namkug Kim Asan Medical Center, Korea. [email protected]

PURPOSE: Prompt and accurate detection of various trauma-related findings in whole body trauma computed tomography (CT) is a crucial step in the emergency department. There is a limitation to annotate all trauma-related finding by an expert in the supervised-learning algorithm. The purpose of this work was to develop and evaluate an unsupervised trauma-related finding detection algorithm in whole body trauma CT using generative adversarial networks (GANs).MATERIALS AND METHODS: We trained a progres-sive growing of GAN (PGGAN) to generate realistic artificial CT images, using the training set of 11,775 normal chest and/or abdominopelvic CT scans (172,249 chest slices and 301,584 abdominopelvic slices). Test set consisted of total of 200 axial slices of WBCT images (100 abnormal and 100 normal images) in trauma patients. Using our simplified AnoGAN model, PGGAN-trained generator yields a corresponding realistic fake image to a given test image by minimizing the mean square error between the fake and the test images. The differences between the fake and the test image on attention maps can detect and localize abnormal findings. For evaluation of the detection performance, we defined 7 clinically significant traumatic lesions (hemothorax, hemomediastinum, pneumothorax, pneumomediastinum, hemoperitoneum, hemoretroperitoneum, and pneumoperitoneum). If the attention map partially included the traumatic lesions, it was considered a positive detection.RESULTS: Total sensitivity per slice was 95.0% (95/100) and total sensitivity per lesions was 94.4% (135/143). For each traumatic lesion, sensitivity was 100% for hemothorax, 95.2% for hemomediastinum, 95.5% for pneumothorax, 93.3% for hemoperitoneum, 84.6% for hemoretroperitoneum, and 100% for pneumoperitoneum. Evaluation of other parameters of performance was limited due to difficult quantification and calculation of non-pathologic false positives.CONCLUSION: An unsupervised automated algorithm using GANs can provide the highly sensitive detection of various and multiple traumatic lesions on unseen CT scans.

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SS 26 AB-06 16:50Implementation of split-bolus CT protocol to reduce radiation dose in trauma patientsLi shyan Ch'ng, Ai Ping Phuar, Sii Ing Yun Sungai Buloh Hospital, Malaysia. [email protected]

PURPOSE: Split bolus protocol is a contrast medium injection technique divided into two boluses that provides both arterial and portal venous enhancement with a single pass of the computed tomography (CT) gantry. This technique would reduce CT dose to trauma patients who are mostly in the young age group compared to multiphase scans acquired sequentially.MATERIALS AND METHODS: A prospective study carried out on adult trauma patients who were randomly selected for multiphase or split bolus CT protocol from January 2017 till July 2017. There were 37 patients (25 men; mean age, 30.5 years) scanned using split bolus protocol and 45 patients (36 men; mean age, 35.1 years) were scanned using multiphase protocol. The CT image quality were evaluated using Likert Scale (1-5) and enhancement of the abdominal organs, portal vein and abdominal aorta were measured in Hounsfield units. CT dose were measured by dose length product (mGy.cm) and effective dose (mSv).RESULTS: There was significant reduction in radiation

dose using split bolus protocol (p = 0.000) with 54% reduction compared to multiphase scan. The average dose using split bolus protocol was 10 mSv and average dose for multiphase scan was 23 mSv. No significant difference in enhancement of the abdominal organs, portal vein and abdominal organs noted. The enhancement of abdominal aorta was higher in the split bolus scans compared to multiphase scans (p = 0.002). Image quality score for split bolus protocol was 4.2 and multiphase scan was 4.4.CONCLUSION: Split bolus CT protocol would be an alternative CT protocol for trauma patients with comparable arterial and venous enhancement and significant reduction in dose compared to multiphase scan.

SS 26 AB-07 17:00Effect of lowering iodinated contrast material administration for CT on acute hypersensitivity reactions: an observational studyJung Hee Son1, Hyo Jung Park1, Tae-Bum Kim1, Min Kyoung Kang1, Kyunghwa Han2, Eun Hye Kim1, Ah Young Kim1, Seong Ho Park1 1Asan Medical Center, 2Severance Hospital, Korea. [email protected]

PURPOSE: Although the concept of dose independence in acute hypersensitivity reactions to iodinated contrast media (ICM) is widely prevalent, clinical data to support or oppose against lowering ICM administration as a prophylactic method are scarce. The purpose of this study was to determine the effect of lowered administration of ICM for computed tomography (CT) on acute hypersensitivity reactions.MATERIALS AND METHODS: This observational study enrolled 21,947 adults (> 18 years) undergoing 25,119 contrast-enhanced abdominal CT examinations between August 2016 and January 2017 (the control period) and 23,019 adults undergoing 26,491 contrast-enhanced abdominal CT examinations between August 2017 and January 2018 (the intervention period), both of which were in an outpatient setting. CT examinations during intervention period used reduced administration of ICM by lowering CT tube voltage: 100 kVp, 1.5 ml/kg (maximum 130 ml) of nonionic ICM, and 2.5 or 3 ml/s injection speeds during intervention period vs. 120 kVp, 2 ml/kg (maximum 150 ml) of nonionic ICM, and 3 or 4 ml/s injection speeds during control period. Per-examination rates of acute hypersensitivity reactions and breakthrough reactions (i.e., acute hypersensitivity reactions occurring despite premedication) to ICM were compared between control and intervention periods using multivariable analysis, and adjusted relative risk (RR) values (i.e., intervention/control), were calculated

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using Poisson regression with generalized estimating equations.RESULTS: The rate of acute hypersensitivity reactions was significantly lower during the intervention period compared with the control period: 1.42% (376/26,491) versus 1.86% (468/25,119), with a multivariable-adjusted RR of 0.86 (95% CI, 0.74-0.99; p = 0.042). The rate of breakthrough reaction rate was also decreased during the intervention period albeit without statistical significance: 4.18% (131/3133) vs. 5.39% (161/2985), with a multivariable-adjusted RR of 0.83 (95% CI, 0.66-1.04; p = 0.111).CONCLUSION: Reducing the dose and injection speed of ICM administration by lowering CT tube voltage could be a practical means to decrease the risk of acute hypersensitivity reactions to ICM.

SS 26 AB-08 17:10Shear wave dispersion imaging for acute interstitial edematous pancreatitis: preliminary studyEun Sun Lee1, Hyun Jeong Park2 1Chung-Ang University Hospital, 2Chung-Ang University Medical Center, Korea. [email protected]

PURPOSE: To invest igate the performance of ultrasound shear wave dispersion (SWD) imaging for tissue viscosity in diagnosis of acute interstitial edematous pancreatitis and evaluation of severity of disease.MATERIALS AND METHODS: From June 2018 to April 2019, we performed abdominal ultrasound with shear wave imaging under clinical impression of acute pancreatitis to 31 patients, who complained of epigastric pain. The shear wave imaging includes conventional elastography (SWE) with a propagation map and newly developed simultaneous SWD, reflecting tissue viscosity. At least, three measurements with different frames were obtained at pancreatic body under guidance of a propagation map as a confidence map. If acute pancreatitis is diagnosed clinically, the patient underwent abdominal CT within a week for evaluation of disease severity.RESULTS: A total of 18 patients from included 31 were diagnosed as acute pancreatitis with clinical criteria. There was significant difference of median SWD values between acute pancreatitis groups and non-acute pancreatitis group (p = 0.008). SWD values were also significant correlated with CT severity index of acute pancreatitis (r = -0.52, p = 0.003) and patient’s hospital stay (r = -0.52, p = 0.003). Conventional SWE did not show any statistical significance between those two groups.CONCLUSION: SWD would be helpful for diagnosis

and evaluation of severity of acute pancreatitis.

SS 26 AB-09 17:20Prediction of malignant potential in intraductal papillary mucinous neoplasm of the pancreas: contrast-enhanced CT versus MRI using revised 2017 international consensus guidelineJi Eun Lee1, Seo-Youn Choi2, Min Hee Lee1, Jung Hoon Kim3 1Soonchunhyang University Bucheon Hospital, 2Soonchunhyang University College of Medicine, 3Seoul National University Hospital, Korea. [email protected]

BACKGROUND: Several changes have been made to the revised 2017 international consensus guideline for management of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. However, the diagnostic performance is yet to be verified.PURPOSE: To evaluate the revised 2017 international consensus guideline for predicting malignant potential of pancreatic IPMNs and compare diagnostic performance and intermodality agreement between contrast-enhanced CT and MRI.MATERIALS AND METHODS: In this retrospective study, two radiologists analyzed the preoperative contrast-enhanced CT and MRI of 86 patients (mean age, 67.6 years ± 8.9 [standard deviation], with 47 men and 39 women) with surgically resected pancreatic IPMNs (benign = 58, malignant = 28) from January 2007 to December 2017, according to the revised 2017 international consensus guideline. Based on the number of high-risk stigmata and worrisome features, a scoring system was developed. The diagnostic performance of CT and MRI were analyzed using receiver operating curve analysis. Intermodality agreement was assessed using weighted k and intraclass correlation coefficient values.RESULTS: On both CT and MRI, enhancing mural nodule, abrupt main pancreatic duct (MPD) caliber change with distal pancreatic atrophy, lymphadenopathy, larger MPD size and faster cyst growth rate were more common in malignant IPMNs than benign (p < 0.05). For clinical variables, elevated serum carbohydrate antigen 19-9 level and history of pancreatitis were more common in malignant IPMNs (p < 0.05). The diagnostic performance of CT (AUC = 0.83) and MRI (AUC = 0.86) for predicting malignant IPMNs were comparable without a significant difference (p = 0.43). Intermodality agreement was good (k = 0.70) for the total score.CONCLUSION: The revised features of the 2017 international consensus guideline were useful in identifying malignant intraductal papillary mucinous neoplasms (IPMNs). The diagnostic performance for

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prediction of malignant IPMNs was comparable between CT and MRI and showed good intermodality agreement.

SS 26 AB-10 17:30Modified breath-hold compressed-sensing 3D MR cholangiopancreatography at 3T: image quality analysis and clinical feasibility assessmentSol ki Kim, Ji Soo Song, Weon Jang, Hyo sung Kwak Chonbuk National University Hospital, Korea. [email protected]

PURPOSE: To prospectively evaluate the clinical feasibility and image quality, both qualitatively and quantitatively, of modified breath-hold compressed-sensing magnetic resonance cholangiopancreatography (BH-CS-MRCP) and conventional navigator-triggered MRCP.MATERIALS AND METHODS: Data from 124 patients with suspected pancreaticobiliary diseases (M:F = 58:66; mean age, 64.5 years) who underwent conventional MRCP and modified BH-CS-MRCP on a 3T MR scanner were analyzed. Two radiologists independently reviewed and graded, using a 5-point Likert-type scale, image degradation by artifacts, background suppression, overall image quality, and duct visualization of 9 segments of the pancreaticobiliary system. Images with an average score of 3 or higher were deemed adequate. Communication between a cyst and the pancreatic duct (PD) was analyzed. Signal-to-noise ratio (SNR) of the common bile duct (CBD), contrast ratio between the CBD and periductal tissue, and contrast-to-noise ratio (CNR) of the CBD and liver were measured.RESULTS: Modified BH-CS-MRCP showed significantly less artifacts with better background suppression and overall image quality. Duct visibility was significantly better with modified BH-CS-MRCP, except at the right 1st level intrahepatic duct (IHD) (p = 0.057), right (p = 0.232) and left 2nd level IHD (p = 0.053), and proximal PD (p = 0.130). Modified BH-CS-MRCP demonstrated communication between a cyst and the PD better than conventional MRCP (96.7% vs. 76.7%, p = 0.048). SNR, contrast ratio, and CNR were significantly higher with modified BH-CS-MRCP (p < 0.001).CONCLUSION: Modified BH-CS-MRCP showed comparable or better image quality than conventional MRCP, with improved visualization of communication between a cyst and the PD.

SS 26 AB-11 17:40The efficacy of texture analysis using ZOOMit coronal diffusion-weighted imaging at 3T MRI for differentiating benign from malignant distal bile duct strictureKi Choon Sim, Beom Jin Park, Nayeon Han, Min Ju Kim, Yeo eun Han, Deuk Jae Sung Korea University Anam Hospital, Korea. [email protected]

PURPOSE: To investigate the diagnostic efficacy of ZOOMit coronal diffusion-weighted imaging (ZC-DWI) and MR texture analysis (MRTA) for differentiating benign from malignant distal bile duct strictures.MATERIALS AND METHODS: We retrospectively enrol led total 71 pat ients with distal bi le duct s t r ic ture who underwent magnet ic resonance cholangiopancreatography (MRCP). ZC-DWI obtained as coronal plane along the bile duct course. MRTA features (mean, standard deviation, mean of positive pixels, entropy, kurtosis, skewness) were extracted from the area of small bile duct stricture on apparent diffusion coefficient (ADC) map of ZC-DWI before and after spatial filtration using commercially available software (TexRAD). For quantitative analysis, mean ADC value at sites suspected strictures were assessed on both ZC-DWI and conventional DWI (C-DWI). For qualitative analysis, two readers independently reviewed two image sets containing different DWIs, and receiver operating characteristic (ROC) curve analysis was assessed.RESULTS: Among 71 patients, 26 patients were confirmed as malignant stricture. Multiple MRTA parameters showed a statistically different distribution in benign and malignant strictures including mean, entropy, mean of positive pixels, and kurtosis at spatial filtration values 0, 5, and 6 mm. Entropy showed the largest area under the ROC curve (AUC) (0.915; 95% CI, 0.823 to 0.968; > 3.39, sensitivity of 84.62% and specificity of 95.45% for the diagnosis of malignant stricture). Average ADC value using ZC-DWI of malignant stricture (1.124 × 10-3 mm2/s) was lower than that of benign stricture (1.522 × 10-3 mm2/s) (p < 0.001). AUC for differentiating benign from malignant stricture was higher in the image set with ZC-DWI than that of C-DWI (0.939, p = 0.010).CONCLUSION: High entropy using MRTA is potentially associated with a malignant distal bile duct stricture and the addition of ZC-DWI to conventional MRCP is more helpful for differentiating benign from malignant bile stricture.

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What's new in GI tract imaging

Chairperson(s)Jae-Joon Chung Gangnam Severance Hospital,

KoreaMin Ju Kim Korea University Anam Hospital, Korea

SS 35 AB-01 16:00Added value of the radiomic signature for predicting prognosis of locally advanced gastric cancer in the preoperative settingJaeseung Shin1, Sung Won Kim2, Joonseok Lim2, Yong-Min Huh3 1Yonsei University Health System, 2Severance Hospital, 3Yonsei University College of Medicine, Korea. [email protected]

PURPOSE: To evaluate the added value of the radiomic signature for predicting recurrence-free survival (RFS) of locally advanced gastric cancer using preoperative contrast-enhanced abdominal CT, compared with the clinical prediction model.MATERIALS AND METHODS: This retrospective study included 349 patients who underwent curative resection for locally advanced gastric cancer in 2010 without neoadjuvant therapies as training cohort. External validation cohort with 61 patients was collected from another hospital. Clinical factors which were available in the preoperative setting including conventional CT staging and endoscopic data were obtained and a total 442 of radiomic features were extracted from the preoperative CT. To predict RFS, the radiomic model was developed using penalized Cox regression with a least absolute shrinkage and selection operator with ten-fold cross-validation. Internal and external validations were performed using a bootstrapping method (n = 1000) for each validation. The incremental values of radiomic features were evaluated by using the integrated area under the receiver operating characteristic curve (iAUC).RESULTS: The clinical model included two independent factors, CT Borrmann type 4 and extramural nodular infiltration, and the radiomic model consisted of selected seven features. The merged model was built using both clinical and radiomic features. In the internal validation, iAUC (95% confidence interval [CI]) for the clinical, radiomic, and merged models were 0.616 (0.570, 0.663), 0.714 (0.667, 0.759), and 0.719 (0.674, 0.764), respectively, and iAUC difference between merged model and clinical model was 0.102 (p < 0.001). In the external validation, the three models yielded iAUC (95%

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CI) with 0.594 (0.544, 0.636), 0.652 (0.628, 0.674), and 0.653 (0.630, 0.673), respectively. The merged model improved RFS prediction when compared with the clinical model (iAUC difference 0.057; p = 0.014).CONCLUSION: The radiomic signature based on CT images can improve RFS prediction when integrated with the preoperative clinical profiles and has potential as a preoperative imaging biomarker.

SS 35 AB-02 16:10‘Radiologic serosal invasion sign’ as new criteria of T4a gastric cancer on CT: the diagnostic performance and the prognostic significance in patients with advanced gastric cancerSoyoung Park, Myung-Won You, Hye Jin Kang, Seong Jin Park, Dong Ho Lee

Kyung Hee University Medical Center, Korea. [email protected]

PURPOSE: To investigate the diagnostic performance and prognostic significance of a new criterion for radiologic T4a staging on computed tomography (CT) in patients with advanced gastric cancer (AGC).MATERIALS AND METHODS: Between January 2010 and April 2019, 101 patients with pathologically confirmed gastric cancer were collected. Among them, 53 patients with pathologic T3 and T4a cancers were included in this study. Three reviewers assessed preoperative CT scans for radiologic T-staging in two sessions, independently and in consensus at a 2-week interval, while blinded about the pathologic T-stage. The radiologic serosal invasion sign was defined as a nodular extension from the outer gastric wall reaching beyond the perigastric vascular plane and adopted as a new CT criterion for T4a cancer. We evaluated the diagnostic performance, interobserver agreement, and prognostic significance of this sign for the postoperative recurrence.RESULTS: There were 46 pathologic T3 cancers (86.7%) and seven pathologic T4a cancers (13.2%). The diagnostic performance of the radiologic serosal invasion sign in the differentiation between T3 and T4a cancers was as follows: sensitivity, 91.3%; specificity, 71.43%; and accuracy, 88.68% for R1 and sensitivity, 78.26%; specificity, 85.71%; and accuracy, 79.25% for R2. The k-value was 0.624. Among the clinical and pathologic variables, radiologic T4a sign (hazard ratio [HR]: 7.959; 95% confidence interval [CI] 2.358-26.865, p = 0.001), pathologic T4a (HR: 9.819, 95% CI 2.354-40.949, p = 0.002), tumor size (HR: 1.176, 95% CI 1.020-1.356, p = 0.026) and lymphovascular invasion (HR: 6.399, 95% CI 1.424-28.755, p = 0.015) were the significant factors for postoperative recurrence.CONCLUSION: Radiologic serosal invasion sign is

reliable as a new CT criterion for T4a cancer staging in patients with advanced gastric cancer, demonstrating 80% to 88% accuracy. Radiologic serosal invasion sign can also serve as a prognostic factor for postoperative recurrence as well as pathologic T4a stage.

SS 35 AB-03 16:20CT detected gastroduodenal subepithelial tumors: added value of endoscopic ultrasound to distinguish between heterotopic pancreas and other pathologiesEun Sun LeeChung-Ang University Hospital, Korea. [email protected]

PURPOSE: To invest igate the added value of endoscopic ultrasound (EUS) to distinguish between heterotopic pancreas and other pathologies, when CT visualize subepithelial tumors (SETs) in stomach and duodenum.MATERIALS AND METHODS: We retrospectively included patients with gastroduodenal SETs, taken both abdominal CT and EUS around the same time for last 10 years in our institution. Among them, we excluded patients without pathologic confirmation, except for the cases that the possibility of heterotopic pancreas was strongly high on CT or EUS and long-term follow-up CT more than 3 years did not show any change in size and characterization of SETs. Finally, we included 60 patients of gastroduodenal SETs including heterotopic pancreas (n = 22; surgery confirmed, n = 7), gastrointestinal stromal tumor (n = 24), leiomyoma (n = 4), neuroendocrine tumor (n = 3), schwannoma (n = 2), and others (n = 5). One radiologist and one gastroenterologist blindly reviewed all EUS and CT studies of included patients in consensus and recorded imaging findings. Diagnostic performance of each imaging character on CT and EUS was evaluated by univariate as well as multivariate analysis.RESULTS: To distinguish heterotopic pancreas from other SETs, micro-lobulating contour, hyperechogenicity than proper muscle layer, internal microcystic-tubular structure and oval shape, larger than 1.64 of ratio were significant EUS features. On contrary, micro-lobulating contour, iso-attenuation with pancreas on portal venous phase, homogeneous enhancement, macrocystic structure and oval shape, larger than 1.64 of ratio were identified as significant CT features. However, multivariate logistic regression study revealed that micro-lobulating contour (r = 0.67, p < 0.0001), hyperechogenicity than proper muscle layer (r = 0.27, p = 0.04), internal microcystic-tubular structure (r = 0.53, p < 0.0001) on EUS were only independent factors in diagnosing heterotopic pancreas.

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CONCLUSION: EUS would play a key role in diagnosis of gastroduodenal heterotopic pancreas to avoid unnecessary surgery, especially when CT diagnosis is indeterminable.

SS 35 AB-04 16:30Role of multidetector CT in differentiating the common primary small bowel neoplasmsHuyen Le, Duc Vo

UMC, Ho Chi Minh city, Vietnam. [email protected]

PURPOSE: To analyze the role of multidetector computed tomography (MDCT) in differentiating the common primary small bowel tumors.MATERIALS AND METHODS: We performed a study from the medical database from January 2015 to May 2018 at University Medical Center and Cho Ray Hospital. The inclusion criteria were as follows: pathologically proven primary small bowel neoplasms and MDCT performed with intravenous contrast media before biopsy or surgery. Radiologist were blinded to the pathological information, reviewed the image findings according to the data collection paper. The MDCT features of small bowel tumors were analyzed including anatomical distribution, pattern of growth (polyp, extramural growth and bowel wall thickening), enhancement, hyperplasia vascular on tumor surfaces, size and lymph node characteristics. Each finding was compared with pathology report to evaluate the specificities, sensitivities and positive predictive value (PPV).RESULTS: Data of 83 patients met the criteria for including in the study. The study included 30 GISTs, 22 lymphomas, 20 adenocarcinomas and 11 others. Anatomical location is not a potential finding in differentiating among small bowels in clinical practice. The extramural growth pattern is reliable prediction of GIST, with PPV of 82.3%. All of GISTs show moderate to avid enhancement. Tumor density of greater than or equal to 110 HU is likely to be GIST, with PPV of 84.9%. Proliferation of blood vessels on tumor surfaces (BVoST) can help discriminate GIST from the others, with PPV of 92%. Bowel wall thickening is the common pattern of adenocarcinoma and lymphoma. Apple-core-like, shoulder defect and focal involvement are probably findings of adenocarcinoma, with PPV of 81.8%, 71.4% and 76.9%, respectively. Aneurysmal dilatation of the lumen and marked thickening wall bowel equal or greater than 25 mm can strongly suggest lymphoma, with PPV of 87.5% and 72.7%, respectively. Enlarged lymph node with shorter axis greater than 20 mm or multiple lymph nodes fused together forming a bulky mass are likely to be lymphoma, with specificity of

100%.CONCLUSION: MDCT findings are potentially useful to differentiate the common primary small bowel neoplasms based on analyzing specific imaging characteristics of each tumor after classifying by growth pattern lesion (Flowchart below).

SS 35 AB-05 16:40Diagnostic sensitivity and specificity of 2-mSv CT versus conventional-dose CT in adolescents and young adults with suspected appendicitis: a post hoc subgroup analysis of the LOCATYousun Ko1, Woo Joo Lee2, Jihoon Park3, Hae young Kim3, Kyoung Ho Lee3 1Asan Medical Center, 2Inha University, 3Seoul National University Bundang Hospital, Korea. [email protected]

INTRODUCTION: To explore heterogeneity across patient or hospital characteristics in the diagnostic sensitivity and specificity of 2-mSv CT relative to conventional-dose CT in adolescents and young adults with suspected appendicitis.MATERIALS AND METHODS: We used the per-protocol analysis set of a randomized controlled trial comparing 2-mSv CT and conventional-dose CT (typically 7 mSv). The data included 2773 patients (median age [interquartile range], 28 [21-35] years) and 160 radiologists from 20 hospitals. We drew forest plots and tested for interaction with logistic regressions to explore heterogeneity across predefined subgroups by patient sex, body size, clinical risk scores for appendicitis, time of CT examination, CT machines, radiologists’ experience, previous site experience in 2-mSv CT, and site practice volume.RESULTS: The 95% CIs for the between-group differences, particularly for sensitivity, were wide due to small sizes (< 200) for the following subgroups: large or small body habitus, high clinical risk score for appendicitis, newer CT machines, hospital with prior

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experience in 2-mSv CT, and hospitals with small appendectomy volume. Otherwise, the 95% CIs in most subgroups contained the previously reported overall between-group differences as well as null hypothesis value (i.e., 0). There was no significant additive or multiplicative treatment-by-subgroup interaction for either sensitivity or specificity.CONCLUSION: We found no notable subgroup heterogeneity, which indicates that 2-mSv CT can replace conventional-dose CT in diverse populations. Further studies are needed for the populations for which our subgroups were small.

SS 35 AB-06 16:50Neural network-based diagnosis of acute appendicitis on contrast-enhanced CT in patients with abdominal painJin Joo Park1, Yoonho Nam2, Kyung Ah Kim1 1The Catholic University of Korea, St. Vincent’s Hospital, 2The Catholic University of Korea, Seoul St. Mary’s Hospital, [email protected]

PURPOSE: To investigate the feasibility of a neural network-based automatic classification for the diagnosis of acute appendicitis on contrast-enhanced computed tomography (CT) of patients visited emergency room (ER) with abdominal pain.MATERIALS AND METHODS: This retrospective study included 80 patients (M:F = 39:41; mean age, 44 years old) who visited ER with abdominal pain and underwent contrast-enhanced abdominopelvic CT in April, 2019. For all 80 CT image sets of portal phase, 3D isotropic cubes (4 × 4 × 4 cm3) including appendix regions were manually extracted and labeled as acute appendicitis or normal appendix by an abdominal radiologist. A 3D convolutional neural network was trained to perform binary classification for input 3D images. In the training process, cross-entropy loss was used and kernel size was 3 for all convolutional layers. To reduce over-fitting, several data augmentation processes such as shifting, flipping, adding random noises were performed. 5-fold cross validation was used. For each model, 64 subjects were used to train the network with same hyper-parameters and remaining 16 subjects were tested using the trained network. From the test results, diagnostic performance was assessed for all subjects.RESULTS: Accuracy for diagnosis of acute appendicitis of a neural network-based automatic classification was 82% (66/80). Sensitivity, specificity, positive predictive value and negative predictive value were 92.50%, 72.50%, 77.08%, and 90.62%, respectively.CONCLUSION: Neural network-based automatic classification was feasible with high diagnostic

performance in diagnosis of acute appendicitis on contrast-enhanced CT of patients visited ER with abdominal pain.

SS 35 AB-07 17:00Enhanced assessment of bleeding in blunt abdominal trauma using contrast-enhanced Ultrasound: comparison with multidetector CT based on angiographJisun Lee1, Yook Kim1, Junghwan Lee1, Kil Sun Park2 1Chungbuk National University Hospital, 2Chungbuk National University College of Medicine, Korea. [email protected]

PURPOSE: To evaluate the accuracy of contrast-enhanced ultrasound (CEUS) for assessing the bleeding in solid organ injury from blunt abdominal trauma using angiography as the reference standard and to compare it with contrast-enhanced multidetector computed tomography (MDCT).MATERIALS AND METHODS: Thirty patients with 34 lesions of blunt abdominal trauma who underwent CEUS, MDCT, and angiography were enrolled in this retrospective study. Injuries included: liver (n = 18), kidney (n = 5), and spleen (n = 11). Extravasation of contrast agent was classified into three types: (a) isolated pseudoaneurysm; (b) pseudoaneurysm with low velocity extravasation; and (c) active extravasation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CEUS for detection and classification of bleeding were calculated based on angiography. The receiver operating characteristic (ROC) curve analysis of each test was performed and compared.RESULTS: All 24 extravasations of contrast agent were detected in both CEUS and MDCT and other 4 lesions without bleeding were equally observed in CEUS and MDCT. Bleedings were classified into 4 isolated pseudoaneurysms, 8 pseudoaneurysms with low velocity extravasation, and 12 active extravasations based on angiography. Sensitivity, specificity, PPV, NPV, and accuracy for assessment of bleeding were 100.0%, 66.7%, 93.3%, 100.0%, and 94.1%, respectively, for CEUS and 92.3%, 50.0%, 85.7%, 66.7%, and 82.4%, respectively, for MDCT. The area under the ROC curves (AUC) of CEUS and CT were 0.900 and 0.765, respectively and there was no statistically significant difference between the two examinations (p = 0.81).CONCLUSION: CEUS and MDCT exhibited comparable consistency with angiography for both detection and classification of bleeding in patients with blunt abdominal trauma. Therefore, it could be possible to perform CEUS as the first-line approach to determine appropriate management in blunt abdominal trauma.

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SS 35 AB-08 17:10Contrast-enhanced abdominal CT prior to closure of temporary ileostomy in patients who underwent colorectal cancer surgery: can it replace water-soluble contrast enema?Yeun-Yoon Kim1, Joonseok Lim2

1Samsung Medical Center, 2Severance Hospital, Korea. [email protected]

PURPOSE: To investigate the utility of contrast-enhanced abdominal CT prior to ileostomy closure for prediction of post-ileostomy closure anastomotic leakage (PCAL) in patients who received colorectal cancer surgery.MATERIALS AND METHODS: Among 736 patients who underwent left-sided colorectal cancer surgery and ileostomy from 2014 to 2016 at our institution, 617 patients subsequently received ileostomy closure. Of these, we included 127 patients who underwent contrast-enhanced abdominal CT less than a month before ileostomy closure for evaluation of chemotherapy response or patient symptom. Two board-certified radiologists retrospectively and independently evaluated several CT features of colorectal or coloanal anastomosis and the perianastomotic area, which could be associated with PCAL, followed by consensus interpretation. PCAL was identified by a requirement of operative management or percutaneous drainage of the perianastomotic abscess, or a description of anastomotic leakage on post-ileostomy closure CT. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to predict PCAL. In addition, to evaluate the matching accuracy between CT and water-soluble contrast enema (WSCE), WSCE studies in 45 patients performed prior to ileostomy closure and within a month from CT were retrospectively reviewed.RESULTS: CT features of anastomotic mural defect (OR [odds ratio], 5.250; p = 0.017), sinus or tract (OR, 4.864; p = 0.041), perianastomotic abscess (OR, 7.292; p = 0.003), and ischemic colitis (OR, 5.769; p = 0.004) were significantly associated with PCAL in univariable logistic regression analysis. Multivariable logistic regression model for prediction of PCAL had an area under the ROC curve of 0.717 (p = 0.008) with optimal sensitivity and specificity of 57.1% and 86.7%, respectively. The prediction by CT and WSCE had a matching accuracy of 84.4% (38 of 45).CONCLUSION: Contrast-enhanced abdominal CT features prior to closure of ileostomy were moderately predict ive of PCAL. A high matching accuracy between CT and WSCE was observed in a subgroup of patients. Contrast-enhanced abdominal CT allows a comprehensive analysis of colorectal or coloanal anastomosis and may serve as a substitute for WSCE

before ileostomy closure in colorectal cancer patients.

SS 35 AB-09 17:20Preoperative staging of rectal cancer: FDG-PET/MRI with dedicated liver and rectal MRI versus current standard of care protocolJeong Hee Yoon1, Jeong Min Lee2, Won Chang3, Hyun-ju Lim4, Hyo-Jin Kang1 1Seoul National University Hospital, 2Seoul National University College of Medicine, 3Seoul National University Bundang Hospital, 4National Cancer Center, Korea. [email protected]

PURPOSE: To compare the rectal cancer clinical staging capability of PET/MRI including dedicated liver and rectal MRI versus the current standard of care protocol (chest/abdominopelvic computed tomography [CT] and rectal MRI).MATERIALS AND METHODS: From January 2016 to August 2017, this prospective study recruited participants with newly diagnosed advanced mid to low rectal cancers. Participants underwent both PET/MRI with dedicated rectal and liver MRI and standard of care protocol within three weeks. Thereafter, M-staging accuracy was determined using 6-month clinical follow-up or biopsy results as the reference standard. Frequency of identified absence of metastases and effective doses were also compared between the protocols and agreement in M-stage classification was assessed. Nonparametric statistical analyses were performed at 0.05 significance level.RESULTS: Seventy-one participants (M:F = 43:28; mean age, 61 ± 9 years) were enrolled. The standard of care protocol was not able to determine M-stage due to indeterminate lesions in 22 out of 71 participants (31%, 95% CI: 20.5-43.1%), whereas in the same sub-cohort PET/MRI correctly identified all 14 participants (100%, 95% CI: 76.8-100%) without metastases and seven out of eight participants (87.5%, 95% CI: 47.4-99.7%) with later confirmed metastases. In all participant, PET/MRI showed a significantly higher specificity to identify participants without metastasis, compared with standard of care protocol (98.2% [54/55] vs. 72.7% [40/55], p < 0.001). PET/MRI’s effective dose was significantly lower than with the standard of care protocol (6.2 ± 1.1 mSv vs. 10.3 ± 5.3 mSv, p < 0.001).CONCLUSION: PET/MRI with dedicated rectal and liver MRI can facilitate the staging work-up of newly diagnosed advanced rectal cancers by serving as a problem-solving modality that can help accurately stage indeterminate lesions and detect comorbidities.

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SS 35 AB-10 17:30Association between texture analysis parameters and molecular biologic KRAS mutation in non-mucinous rectal cancerSung jae Jo1, Seung Ho Kim1, Sang Joon Park2 1Inje University Haeundae Paik Hospital, 2Seoul National University Hospital, Korea. [email protected]

PURPOSE: To evaluate the association between magnetic resonance imaging (MRI)-based texture parameters and Kirsten-ras (KRAS) mutation in patients with non-mucinous rectal cancer.MATERIALS AND METHODS: Forty-six patients who had undergone preoperative rectal MRI and subsequent surgery were included in the study. They all had pathologically confirmed rectal non-mucinous adenocarcinoma. Texture analysis was performed on axial T2-weighted images (T2WI) using a dedicated software. Regions of interest were drawn along the tumor border to cover the entire tumor. Representative texture parameters for each tumor were calculated and analyzed. The association was statistically analyzed using the Mann-Whitney U test. To extract an optimal cut-off value for prediction of KRAS mutation, receiver operating characteristic curve analysis was performed and corresponding predictive values were estimated. Molecular biologic results on KRAS mutation served as the reference standard.RESULTS: Skewness in the mutant group (n = 22) was significantly higher than that in the wild-type group (n = 24) (0.221 ± 0.283; -0.006 ± 0.178, respectively, p = 0.003). The AUC of skewness was 0.757 (95% CI, 0.606 to 0.872) with a maximum accuracy of 71%, a sensitivity of 64%, and a specificity of 78%. None of the other texture parameters were associated with KRAS mutation (p > 0.05).CONCLUSION: Skewness derived from texture analysis based on T2WI was associated with KRAS mutation in patients with non-mucinous rectal cancer and the estimated accuracy for prediction of KRAS mutation was 71%.

SS 35 AB-11 17:40Correlation of hemodynamic parameters derived from intravoxel incoherent motion (IVIM) and perfusion CT in rectal cancerHongliang Sun1, Yanyan Xu2, Qiaoyu Xu3, Wu Wang1 1China-Japan Friendship Hospital, China, 2Graduate School of Medical Science, University of the Ryukyu, Japan, 3Beijing Chaoyang Hospital, Capital Medical University, China. [email protected]

PURPOSE: To assess the correlation of perfusion parameters between intravoxel incoherent motion magnetic resonance imaging (IVIM-MRI) and whole-volume computed tomography (CT) in patients with rectal cancers.MATERIALS AND METHODS: Totally, 31 patients (M:F = 20:11; mean age, 60.8 years; age range, 26-85 years) with rectal cancers proved by pathology were enrolled in this study. They underwent pelvis magnetic resonance imaging (MRI) and the whole-volume perfusion CT examination successively. The mean interval time between the two examinations was 1.41 days (range, 0-5 days). All pelvis magnetic resonance imaging were performed in a 3.0T MR unit (Philips 3.0T Ingenia, Philips Medical System, The Netherlands) including diffusion-weighted imaging using eight b values (0, 25, 50, 75, 150, 400, 800 and 1000 s/mm2). IVIM perfusion-related parameters (f, perfusion fraction; D*, pseudo-diffusion coefficient; f·D*, the multiplication of the two parameters) were calculated by bi-exponential model analysis. All CT perfusion examinations were completed in 320-slice CT (Toshiba Aquilion one, Toshiba Medical System, Japan), and quantitative values for blood volume, artery flow and flow extraction product were automatically generated using in-house commercial software after regions of interest (ROI) being selected along the outline of tumor maximal dimension (axial view), meanwhile time-density curves (TDC) were obtained. Correlations between f and CT perfusion parameters were respectively analyzed using Pearson’s or Spearman’s correlation coefficients, D* and f·D* were also similarly analyzed. Interobserver agreement were evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. p＜0.05 was considered to indicate a statistically significant difference.RESULTS: Interobserver reproducibility were relatively good (ICC = 0.7204-0.8953; narrow with of 95% limits of agreement). Significant correlations were showed between D* and BV (r = -0.379; p = 0.036), f and BV (r = 0.458; p = 0.010), however, no correlation was observed between f·D* and CT perfusion parameters.CONCLUSION: D* and f values showed significant correlation with BV value, reflecting potential relationship

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between IVIM perfusion-related parameters and CT whole-volume perfusion quantitative parameters in rectal cancer.

SS 35 AB-12 17:50Agreement between 3D multi-echo Dixon (mDixon) images and T2 field echo (T2 FFE) images for measuring T2* in rectal cancerYanyan Xu1, Hongliang Sun2, Qiaoyu Xu3, Wu Wang2 1Graduate School of Medical Science, University of the Ryukyu, Japan, 2China-Japan Friendship Hospital, China, 3Beijing Chaoyang Hospital, Capital Medical University, China. [email protected]

PURPOSE: To compare T2* values derived from 3D mDixon sequence to values from T2 FFE sequence in rectal cancer and investigate the potential relationship between them.MATERIALS AND METHODS: Totally, 28 patients (mean age, [56.9 ± 13.2] years; range, 35-84 years), including 15 men and 13 women with histologically proved rectal cancer underwent pelvis magnetic resonance imaging (MRI) examination (Philips 3.0T Ingenia, Philips Medical Systems, The Netherlands) including 3D multi-echo Dixon (mDixon) sequence and T2 fast field echo (T2 FFE) sequence. 3D mDixon sequence was performed in 3D mode using six echoes (TR/TE1/DTE [ms], 6.3/1.08/0.8; flip angle, 3°; total scan duration, 14.5 sec), while T2 FFE sequence was performed in 2D mode using five echoes (TR/TE1/DTE [ms], 644/4.0/6.9; Flip angle, 45°; total scan duration, 5.2 min). T2* values for both sequences were automatically calculated after region of interest (ROI) being selected along the outline of tumor maximal dimension (axial view). The T2* values derived from 3D mDixon sequence and T2 FFE sequence were compared by using paired t test. Intra- and interobserver agreement were evaluated using the intra-class correlation coefficient (ICC) and Bland-Altman analysis. P＜0.05 was considered to indicate a statistically significant difference.RESULTS: Intra- and inter-observer reproducibility were relatively good to excellent (T2*mDixon: ICCIntra = 0.9647, ICCinter = 0.8300; T2*FFE: ICCIntra = 0.9675, ICCinter = 0.8800). There was no significant difference in T2* values for the two sequences (T2*mDixon vs. T2*FFE: [43.57 ± 13.21] vs. [43.16 ± 13.73], p = 0.252), and excellent correlations were observed between them (r = 0.991, p < 0.001).

CONCLUSION: T2* values derived from 3D mDixon sequence showed excellent agreement with the values from T2 FFE sequence, thus 3D mDixon sequence is a viable alternative for T2* measurement in rectal cancer with significantly short scan time.

predicting prognosis of hcc - conplus.co.krkcr2019/down/abs/ss/kcr 2019 abstract book … · mri...

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