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Functional MR Cholangiography: Diagnosis of Functional Abnormalities of the Gallbladder and Biliary Tree

OBJECTIVE. Our objective was to describe the technique and utility of functional MRcholangiography (fMRC) in the evaluation of the gallbladder and biliary tree.

CONCLUSION. FMRC has the potential to provide a comprehensive examination for the an-atomic and functional assessment of the gallbladder and biliary tree. Complex anatomic abnormalitiesand functional disorders can be shown by fMRC, including biliary obstruction and extravasation.

unctional MR cholangiography(fMRC) is an emerging techniquethat has the potential to provide acomprehensive evaluation for the

anatomic and functional assessment of the gall-bladder and biliary tree. FMRC is performedwith a contrast agent such as mangafodipir tri-sodium (Teslascan, Nycomed Amersham),which is excreted via the biliary system, whereit causes T1 shortening of bile [1]. Hence, an fMRCsequence can be performed as a high-resolutionT1-weighted 3D gradient-recalled echo (GRE)sequence. With its intrinsic high signal-to-noiseratio, this sequence affords a smaller pixel sizethan that achieved by conventional single-shotfast spin-echo MRC, sonography, and scinitig-raphy. As such, not only can anatomic abnor-malities such as strictures, filling defects, andsubtle ductal anomalies be detected, but func-tional abnormalities such as cholecystitis, ductalobstruction, and biliary extravasation can be de-finitively established. In this pictorial essay, wewill discuss the fMRC technique, its advantagesover other techniques, and provide examplesthat illustrate the value of fMRC (Figs. 1–11).

TechniqueAlthough several hepatobiliary contrast agents

are being developed that may be suitable for the

performance of an fMRC sequence in the future[2], mangafodipir trisodium is a U.S. Food andDrug Administration–approved contrast agentfor the evaluation of liver lesions [3, 4] and is usedfor fMRC imaging [1, 5]. FMRC imaging con-stitutes an off-label use of mangafodipir trisodium.As of March 2004, manufacturing of man-gafodipir had been suspended by NycomedAmersham, but resumption of manufacturingis expected.

FMRC images of the biliary tree are ob-tained as follows: Approximately 10–20 minafter the injection of mangafodipir (dose, 5µmol/kg or 0.5 mL/kg administered at 2–3mL/min), high-resolution 3D GRE imagesare obtained in coronal, coronal oblique, andaxial planes (TR/TE, 6/2.2; flip angle, 40°;field of view, 28 cm2; matrix, 256 × 128; 3.0-mm slice thickness with zero fill interpola-tion to yield 64 images per slab at 1.5-mmincrements with 1.5-mm overlap; number ofexcitations, 0.5; bandwidth ± 62 kHz), usu-ally requiring two slab overlapping prescrip-tions. If initial images do not show contrastmaterial in the biliary tree, this sequence canbe repeated as needed at later intervals to ob-tain additional delayed imaging. If clinicallyindicated, we advocate that delayed imagingbe performed at 2-hr intervals after injection

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Hepatobiliary ImagingFayad et al.fMRC Diagnosis of Gallbladder and Biliary Tree Abnormalities

Pictorial Essay

Laura M. Fayad1

Ihab R. Kamel1Donald G. Mitchell2David A. Bluemke1

Received June 8, 2004; accepted after revision October 6, 2004.

1Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, 601 N Wolfe St., JHOC 3171C, Baltimore, MD 21287. Address correspondence to L. M. Fayad (lfayad1@jhmi.edu).2Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA.

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as needed, until visualization of the contrastagent in the gallbladder and duodenum ispossible (Figs. 2 and 3). The exact time in-terval at which delayed imaging is executedis in part dependent on the availability of theMR scanner.

Because the excretion of mangafodipirinto the biliary tree interferes with success-ful visualization of biliary fluid on conven-tional T2-weighted MRC sequences (Fig. 4),conventional MRC imaging must be per-formed before excretion of mangafodipir intothe biliary tree. If a conventional T2-weightedMRC sequence is not desired, delayed imag-

ing of the biliary tree may be performed afterthe IV administration of mangafodipir with-out the performance of a conventional single-shot fast spin-echo MRC.

Hence, fMRC imaging can be performed intwo ways, as a combined study with conven-tional MRC (combined MRC) or as a delayedpostcontrast study without conventionalMRC (fMRC alone). The advantage of com-bined MRC is that additional information ob-tained from the T2-weighted contrast agentwithin the ducts may further support findingsseen on fMRC images. The disadvantage isthat additional delayed imaging may be re-

quired if mangafodipir has not been excretedinto the biliary system on early images. How-ever, when additional delayed imaging is per-formed, the transit time of contrast agent intothe biliary tree and gallbladder may be deter-mined and be of value in some instances, suchas in the diagnosis of chronic cholecystitisand partial biliary duct obstructions, entitiesin which delayed filling of the gallbladder andbiliary tree occurs (Figs. 2 and 3). Also, onoccasion, high-signal-intensity bile may havea similar signal intensity to that of the contrastmaterial. It is useful to distinguish excretionof contrast material in the gallbladder from

Fig. 1.—55-year-old woman with acute cholecystitis and metastatic disease to liver.A, Axial single-shot fast spin-echo (SSFSE) MR cholangiography (MRC) image (TR/TE, infinite/186) shows gallbladder (GB) wall thickening and some distention.B, Coronal SSFSE MRC image (infinite/190) shows calculus (C) in GB neck.C, Axial functional MRC image (6/2.2; flip angle, 40°) 4 hr after mangafodipir triso-dium injection shows contrast agent in common bile duct (CBD). Calculus (C) isagain noted in GB neck, but contrast agent has not passed into GB, confirmingacute cholecystitis and cystic duct obstruction by calculus. Multiple metastaticliver lesions are present.

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Fig. 2.—83-year-old woman with chronic cholecystitis.A, Precontrast thick-slab single-shot fast spin-echo MR cholangiography (MRC) image (TR/TE, infinite/800) shows distention of gallbladder and gallstones (arrow), featuresof chronic cholecystitis. Distinction from acute cholecystitis is difficult by conventional MRC images alone.B, Early axial mangafodipir trisodium–enhanced 3D gradient-recalled echo functional MRC (fMRC) image (TR/TE, 6/2.2; flip angle, 40°) performed within 40 min of injectionshows contrast agent in duodenum (arrow) but no filling of gallbladder (GB).C, At 40 min, coronal fMRC image (6/2.2; flip angle, 40°) shows contrast material in duodenum (D) but no filling of gallbladder (GB).D, Two hours later, after injection of morphine sulfate, coronal fMRC image (6/2.2; flip angle, 40°) shows contrast agent is present in cystic duct (CD) and gallbladder (GB).(Fig. 2 continues on next page)

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native bile (Fig. 2E). If, however, imagingwith fMRC alone is needed, mangafodipirmay be injected and subsequent imaging cantake place several hours after injection, poten-tially eradicating the need for delayed imag-ing. Suspected acute cholecystitis is an idealsetting for which fMRC alone may be suffi-cient (Fig. 1). For indications other than acutecholecystitis, including suspected biliary duc-tal obstruction (Figs. 5–7) and biliary leaks

(Fig. 11), we perform combined MRC. AnfMRC sequence is valuable in the evaluationof a potential liver transplant donor for detec-tion of variant biliary ductal drainage [5](Figs. 9 and 10).

Comparison with Other TechniquesOur arsenal of techniques for evaluation

of the biliary tree includes sonography, con-ventional MRC, hepatobiliary scintigraphy,

CT, endoscopic retrograde cholangiography(ERC), and percutaneous transhepatic cho-langiography (PTC).

Sonography is typically the initial tech-nique used for the assessment of the biliarytree and although it is a highly sensitive tech-nique for the evaluation of the gallbladder[6], it is limited in cases in which the biliaryducts are not dilated and for the evaluation ofthe extrahepatic biliary tree [7]. Conven-

Fig. 2. (continued)—83-year-old woman with chronic cholecystitis.E, Axial fMRC image (6/2.2; flip angle, 40°) shows contrast agent in gallbladder lay-ering on nondependent surface (arrow). It is useful to distinguish excretion of con-trast agent in gallbladder from native bile. Enhanced bile is recently excreted bilethat is not concentrated; it layers on top of concentrated nonenhanced bile.

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Fig. 3.—62-year-old woman with chronic cholecystitis.A, Axial mangafodipir trisodium–enhanced 3D gradient-recalled echo functional MR cholangiography (fMRC) image (TR/TE, 6/2.2; flip angle, 40°) shows contrast agent incommon bile duct (CBD) after 20 min. There is no filling of gallbladder (GB).B, Four hours after injection of contrast material, coronal oblique maximum-intensity-projection image obtained from reconstruction of axial fMRC data set (6/2.2; flip angle,40°) shows contrast agent entering cystic duct (CD) and gallbladder (GB). Contrast agent is present in duodenum (D).

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Fig. 4.—66-year-old woman with common bile duct calculi.A, Axial single-shot fast spin-echo MR cholangiography (MRC) image (TR/TE, infinite/186) obtained after mangafodipir trisodium administration shows low-signal-intensityfluid in common bile duct (CBD), obscuring its evaluation.B, Corresponding axial functional MRC (image (6/2.2; flip angle, 40°) shows filling defect (calculus) in CBD surrounded by contrast material. Duodenal contrast material (D)indicates nonobstructing biliary calculus.

Fig. 5.—68-year-old man with carcinoma of pancreas,metastases to liver, and partial obstruction of commonbile duct.A, Coronal single-shot fast spin-echo MR cholangiography(MRC) image (TR/TE, infinite/186) shows narrowing of com-mon bile duct (CBD) by mass (M). Multiple hepatic lesionsare noted, some of which represent metastatic disease.B, Coronal oblique maximum-intensity-projection man-gafodipir-enhanced functional MRC (fMRC) image (6/2.2;flip angle, 40°) obtained from reconstruction of 3D data setagain shows marked narrowing of CBD at level of mass(M). Contrast material is present in duodenum (D) andappeared approximately 4 hr after IV administration.Delayed transit time indicates partial obstruction by mass.C, Axial fMRC image (6/2.2) taken at level of severe duc-tal narrowing shows contrast in CBD. Partially obstruct-ing mass (M) is marked. Multiple lesions are againidentified in liver.

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Fig. 6.—57-year-old woman with pancreatic cancer.A, Thick-slab single-shot fast spin-echo MR cholangiography (MRC) image (TR/TE, infinite/800) shows classic double duct sign of pancreatic carcinoma.B, Axial delayed funtional MRC (fMRC) image (TR/TE, 6/2.2; flip angle, 40°) obtained several hours after mangafodipir trisodium injection shows enhancement of liver paren-chyma without excretion of contrast agent into biliary tree. This finding persisted at 24 hr. Tumor completely obstructs biliary tree.

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Fig. 7.—55-year-old woman with biliary obstruction caused by metastatic ovarian carcinoma, requiring stentplacement across common bile duct. Patency of stent was evaluated by MRI. (Reprinted with permission from [1])A, Coronal single-shot fast spin-echo MR cholangiography (MRC) image (TR/TE, infinite/186) shows limited visu-alization of common bile duct stent. Functionality of stent cannot be assessed.B, Axial mangafodipir trisodium–enhanced functional MRC (fMRC) image (6/2.2; flip angle, 40°) shows excretionof contrast material into dilated intrahepatic biliary tree.C, Coronal mangafodipir trisodium–enhanced fMRC image (6/2.2; flip angle, 40°) shows excretion of contrast mate-rial around stent into duodenum (D), confirming patency.

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Fig. 8.—45-year-old woman with anatomic variant of biliary tree. Axial mangafodipirtrisodium-enhanced functional MR cholangiography image (TR/TE, 6/2.2; flip angle,40°) shows low cystic duct insertion (CD) and ductal configuration that may increaserisk for bile duct injury at laparoscopic cholecystectomy.

Fig. 9.—38-year-old woman evaluated as liver transplant donor with mangafodipirtrisodium–enhanced functional MR cholangiography (fMRC) shows variant ductalanomaly. Coronal oblique maximum-intensity-projection fMRC image (TR/TE, 5.6/2.5;flip angle, 40°) shows segment IV biliary duct draining into right hepatic duct. Otherducts are labeled. CHD = common hepatic duct, CBD = common bile duct.

Fig. 10.—40-year-old man evaluated as liver transplantdonor with mangafodipir trisodium–enhanced func-tional MR cholangiography (fMRC) shows variant duc-tal anomaly that is only seen by fMRC.A, Coronal single-shot fast spin-echo MRC image (TR/TE, infinite/150) shows no significant abnormality. Duc-tal system is not well defined.B, Coronal oblique maximum-intensity-projection fMRCimage (5.6/2.5; flip angle, 40°) shows right posterior bil-iary duct (arrow) draining into left duct.

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tional MRC is a fast, heavily T2-weightedMR sequence that depicts the fluid-contain-ing biliary tree in a noninvasive manner, re-quires no contrast agent administration orpreparation, and portends none of the com-plications associated with invasive cholang-iography. Both MRC and CT have beenestablished as highly sensitive techniquesfor the diagnosis of anatomic abnormalities

of the gallbladder and biliary tree [8, 9].However, after imaging with these cross-sectional techniques, a functional assess-ment of the biliary tree can only be sug-gested based on associated anatomicfindings, including biliary ductal dilatation,stricture, and filling defects. Obstruction ofbile flow cannot be definitively diagnosed.For a functional assessment (noninvasively),

a second test such as cholescintigraphy iscommonly performed.

Hepatobiliary scintigraphy with an imino-diacetic acid derivative such as diisopropyliminodiacetic acid provides functional infor-mation but lacks resolution to show the ana-tomic cause of obstruction. Filling defectsand strictures are uncommonly visualized andthe diagnosis of partial obstruction is not

Fig. 11.—20-year-old man with end-stage liver disease secondary to argininosuccinase synthase deficiency who underwent liver transplantation and experienced postop-erative complication.A, Axial single-shot fast spin-echo MRI image (TR/TE, infinite/100) shows transplanted liver and marked ascites. Focal perihepatic fluid collection (FL) is identified.B, Coronal functional MR cholangiography (fMRC) image (6/2.2; flip angle, 40°) shows mangafodipir trisodium in common bile duct. Anastamosis is marked (A). Additional focus of contrastmaterial is present outside biliary tree, compatible with anastamotic leak (arrow). Contrast agent has passed into duodenum (D); there is no evidence of biliary obstruction.C, Coronal fMRC image (6/2.2; flip angle, 40°) obtained more anteriorly shows contrast agent accumulating outside biliary tree within fluid collection (arrow), compatible with biliary leak.D, Corresponding diisopropyl iminodiacetic acid scan shows biliary leak (arrow), but site of leak is not clearly depicted. For optimal surgical management, it was importantto determine site of biliary extravasation before reoperation.

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made in up to 50% of patients [10]. Scintigra-phy also has false-positive results in nonfast-ing patients, patients with severe hepaticfailure, and patients with hyperbilirubinemia.

Finally, ERC and PTC provide the oppor-tunity for treatment at the time of diagnosisthat the noninvasive techniques discussedhere lack. Although invasive cholangiogra-phy studies are sensitive diagnostic methods,complications result in as many as 11% ofcases [11].

ConclusionFMRC has the potential to provide a com-

prehensive examination for the anatomicand functional assessment of the biliary treeand gallbladder. Its compelling advantage isits ability to depict functional information.Partial and complete obstruction may bedistinguished along with the inciting ana-tomic abnormality, a feature particularlyuseful for treatment planning. In addition,variant bile duct anatomy, complex biliary–

enteric anastamoses, biliary stent patency(particularly nonmetal stents), and sus-pected biliary extravasation can be thor-oughly evaluated with fMRC.

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