Dr . ARUN KUMAR

DEFINITION

• Round or oval opacity smaller than 3 cms in

diameter

• Completely surrounded by lung parenchyma

• No atelectasis

• No lymphadenopathy

• No pneumonia

Lesions more than 3cms are termed as masses.

SPN MASS

CLASSIFICATION ON CT

• Solid-Soft tissue attennuation

• Sub solid-Ground glass attenuation

• Soft tissue with ground glass

attenuation

DIFFERENTIAL DIAGNOSIS FOR SOLID

SPNS

CAUSE CONDITION

Neoplastic (malignant) Primary lung malignancies (non–small cell,

small cell, carcinoid, lymphoma), solitary

metastasis

Benign Hamartoma, arteriovenous malformation

Infectious Granuloma, round pneumonia, abscess,

septic embolus

Noninfectious Amyloidoma, subpleural lymph nodule,

rheumatoid nodule, Wegener

granulomatosis, focal scarring, infarct

Congenital Sequestration, bronchogenic cyst, bronchial

atresia with mucoid impaction

SUB SOLID SPN

TYPE OF CAUSE CONDITION

Malignant LUNG

ADENOCARCINOMA;

Metastasis from

melanoma, renal cell

carcinoma, and

Adenocarcinoma of the

pancreas, breast, and

gastrointestinal tract

Lymphoproliferative

disorders

Benign Organizing pneumonia,

Focal interstitial fibrosis,

Endometriosis

EVALUATION

• Clinical

• Radiological

CLINICAL EVALUATION

• History of smoking,

• Age over 40,

• Occupational exposures (e.g., asbestos),

• Lung fibrosis,

• Coexisting chronic obstructive pulmonary disease (COPD) and emphysema,

• Family history of lung cancer

• Recent travel history,

• Positive skin test for tuberculosis (TB) or

fungus, or

• Presence of other diseases (e.g.,

rheumatoid arthritis)

RADIOLOGICAL EVALUATION

• Chest x ray

• CT scan

• FDG-PET

• BIOPSY

• Newer modalities-Dynamic MR imaging

DW MRI

• FOLLOW UP

MORPHOLOGICAL EVALUATION

• Size

• Location

• Edge Appearance

• Calcification

• Attenuation

• Air Bronchograms and

Pseudocavitation

• Cavitation

• Satellite Nodules

• Feeding Vessel Sign

• Fat

• Water Density

• Contrast Enhancement

• Hemodynamics

• Growth

SIZE

• The smaller the nodule the more likely it

is

benign.

• Limited use in sub solid SPN

Size (cm) LikelihoodRatio

• 3.0 5.23

• 2.1–3.0 3.67

• 1.1–2.0 0.74

• 1.0 0.52

SIZE INTERPRETATION

< 3mm 99.8% benign

4-7mm 99.1%benign

8-20mm 82%benign

>20mm 50%benign

>30mm 7%benign

LOCATION• Attached nodule – length of contact surface of nodule

>50% of nodule diameter or major part of non spherical

nodule is attached to fissure /pleura/vessel implies

benignity.

• BENIGN-Evenly distributed through lung

• MALIGNANT-R>L;UL>LL

Adenocarcinomas – Peripheral

Small cell carcinomas- Central

Metastasis- Peripheral/sub pleural

Associated with fibrosis- Lower lobes

EDGE• Benign lesions - smooth, sharply defined edge .

• Malignant nodules -ill-defined, irregular, lobulated, or

spiculated margin(corona radiate and corona maligna

)

• SHARPLY MARGINATED

Granuloma

Hamartoma or benign tumor

CARCINOID TUMOR

METASTASIS

• Spiculated (corona radiata) –growth of cells along

interstitum

Bronchioloalveolar carcinoma

GRANULOMA OR FOCAL SCARRING

Hamartoma presenting as a sharply defined, round nodule. A. Chest

radiograph shows a round nodule (arrows) in the right upper lobe. B.

CT shows the nodule (arrow) to be rounded in shape and sharply

marginated. Slight lobulation may be seen with hamartomas

Solitary metastasis from a head and neck carcinoma. A left upper

lobe nodule (arrow) is smooth and sharply defined on CT. This

appearance is common with metastases.

Adenocarcinoma. HRCT shows an irregular, spiculated nodule with

multiple

pleural tails. Air bronchograms are visible within the nodule

• PLEURAL TAIL SIGN-linear opacity is seen extending from the edge of a lung nodule to the pleural surface

• CT HALO SIGN-halo of GGO surrounding a nodule.

• Represents hemorrhage,inflammation,infiltration

Fungi: invasive aspergillosis, candidiasis, coccidioidomycosis

Bacteria: tuberculosis, Nocardia, Legionella

Viruses: cytomegalovirus, herpes

Pneumocystis jiroveci (P. carinii)

Bronchiolitis obliterans with organizing pneumonia

Wegener's granulomatosis

Infarct

Metastatic tumor-angiosarcoma,choriocarcinoma,osteosarcoma

Kaposi's sarcoma

Halo sign

a) invasive aspergillosis. HRCT in a young patient with leukemia and

granulocytopenia shows a dense left lower lobe nodule surrounded by a halo

(arrows) of ground-glass opacity. In patients with invasive aspergillosis, the halo

represent hemorrhage surrounding a septic infarction

b) bronchioloalveolar carcinoma, the halo represents the presence of lepidic tumor

growth

• Reverse halo sign-ATOLL SIGN central area of

ground glass attenuation surrounded by a halo or

crescent of consolidation

• Seen in CRYPTOGENIC ORGANIZING

PNEUMONIA

Paracoccidioidomycosis,

• Tuberculosis,

• Lymphomatoid granulomatosis,

• Wegener granulomatosis,

• Sarcoidosis

• Lung cancer after radiotherapy

Reverse halo sign after radiofrequency ablation of a pulmonary metastasis

in a 63 year-old man with pancreatic cancer who previously underwent left

upper lobectomy. (a) CE CT image shows a left-lower-lobe metastasis

(arrow).

(b) CECT image obtained 1 month after radiofrequency ablation shows the

treated metastasis (arrow), which now has mixed attenuation, surrounded

by a ground glass opacity (*) and a well-circumscribed rim of consolidation

(arrowheads)

CALCIFICATION

• Most important characteristic feature

• Best detected on HRCT

• The presence of calcium in an SPN increases its

chances

of being benign

a. Benign

b. Indeterminate

BENIGN PATTERN

a. Homogeneous calcification

b. Dense central (“bull's-eye”)

c. Concentric rings of calcium (“target”)

d. Conglomerate foci of calcification involving a

large part of the nodule (“popcorn”)

CARCINOID TUMOR

MUCINOUS ADENOCARCINOMA.

METASTASES FROM OSTEOGENIC

SARCOMA OR CHONDROSARCOMA

a)Homogeneous calcification. Dense

and uniform calcification of a small right

upper lobe nodule (arrow) is typical of a

benign lesion, usually a tuberculoma

b)Concentric or “target” calcification

(arrow). One or more rings of calcium

may be seen. This pattern is typical

of a histoplasmoma

a)Dense central or “bull's-eye”

(arrows) .This is typical of

histoplasmoma or hamartoma

b)Multiple confluent nodular foci of

calcification (“popcorn” calcification;

arrow) This appearance is typical of

hamartoma and corresponds to

calcification of cartilage nodules

INDETERMINATE

PATTERN

• Stippled

• Eccentric

• Amorphous

Eccentric calcification in an

adenocarcinoma. A lobulated mass

shows a small focus of eccentric

calcification (arrow).

• Dual-energy CT, in which 80- and 140-kV images

are simultaneously obtained, measurement of CT

attenuation values obtained at different kilovolt

peaks may be used to identify areas of calcium

and iodinated contrast material.

• A multicenter trial showed that the use of

unenhanced dual-energy CT to evaluate changes

in attenuation values at 140 and 80 kVp is not

reliable for differentiating benign and malignant

nodules with 3-mm sections and differing

acquisitions for both kilovolt potentials

ATTENUATION

• Soft tissue attenuation in solid SPN

• GGAN , GGAN + Soft tissue attenuation in sub solid SPN

• Classification of Nonmucinous Forms of Lung Adenocarcinoma &CT Features of Subsolid Nodules(2011 IASLC,ATS&ERS )

• Atypical adenomatous hyperplasia GGAN

Adenocarcinoma in situ GGAN with a possible

solid component

Minimally invasive adenocarcinoma GGAN, partly solid

nodule

Lepidic-predominant adenocarcinoma Partly solid nodule,

solid nodule

Invasive adenocarcinoma Partly solid nodule, solid

nodule

• Mean nodule attenuation number could be used to differentiate among AAH (-609 HU), BAC (-450 HU), and invasive adenocarcinomas (-319 HU).

• Although there is currently no standard CT methodology for quantifying the soft-tissue component of SSNs, direct correlation of the soft-tissue component with the degree of invasion or aggressiveness of subsolidadenocarcinomas and patient prognosis and survival has been reported

• Honda et al (45) reported that a ratio of the largest tumor dimension on images obtained with soft-tissue window settings versus that on images obtained with lung window settings of 50% or less indicated an “air-containing type,”(AIS) a ratio of more than 50% indicated a “solid type” lesion(INVASIVE ADENOCARCINOMAS)

AIR BRONCHOGRAM &

PSEUDOCAVITATION

• Presence implies malignancy.

• Most typical of adenocarcinoma or bronchioloalveolar carcinoma.

• Small air-filled cystic areas in the tumor (so-called pseudocavitation),

or small cavities have the same significance as air bronchograms.

• Other causes

Conglomerate mass

Focal pneumonia

Infarction

Rounded atelectasis

Bronchiolitis obliterans with organizing pneumonia

Lymphoma

Lymphoproliferative diseases

Mycetoma (may mimic a bronchogram

CAVITATION

• Both benign & malignant show cavitation.

• The thickness &nature of the wall of a cavity serves as an indicator of its likelihood of being malignant.

• If the thickest part of the wall is less than 5 mm, 95% are benign.

• Nearly 92% of cavities with a wall measuring more than 15 mm in its thickest portion are malignant.

• 51% of cavities with a wall 5 to 15 mm in thickness are benign.

• Cavitary malignant lesions tend to have a thick, nodular wall ; benign lesions often have a thin, smooth wall

Characteristic LikelihoodRatio

Cavity wall thickness (mm)

16 37.97

4–16 0.72

4 0.07

a

c

Cavitary carcinoma. A. Plain radiograph showing a

cavitary left lung mass that represents a squamous cell

carcinoma. B. Cavitary squamous cell carcinoma shown

at two levels. The wall of the cavity is irregular, with

several thick nodular regions (white arrow). The cavity

contains an air-fluid level (black arrows). This is

uncommon in malignancy and may represent

hemorrhage or infection. C. Cavitary adenocarcinoma

shown on HRCT in six contiguous scans. The nodule

contains an irregular cavity; is irregular and lobulated in

shape, notched, and spiculated; and is associated with

pleural tails. It also contains several air bronchograms

• Air fluid level-a mass or nodule may be present

within the cavity. Air outlining or capping the

superior aspect of the mass results in a crescent-

shaped collection of air, termed the “air-crescent”

sign

The axial CT shows a nodule (black arrow) with a

Crescent of air(white arrow) in aspergilloma

• Air fluid level- The presence of an air-fluid level in a patient with

a cavitary SPN tends to indicate a benign lesion, particularly

lung abscess .

• Any infected cystic or cavitary lesion may be associated with an

air-fluid level.

• An air-fluid level is uncommon in a cavitary carcinoma, but may

be seen in the presence of intracavity hemorrhage or

superinfection .

CT scan of a lung

abscess

SATELLITE NODULE

• Small nodules seen adjacent to a larger

nodule or mass & predict benign lesion

• Most common with granulomatous

diseases& infections such as TB

• Only a small percentage of carcinomas are

associated with satellite nodules.

• Galaxy sign in sarcoidosis

Tuberculosis. A right upper lobe nodule is

associated with satellites (arrows). This

appearance is most typical of a benign

process but sometimes is seen with

carcinoma

FEEDING VESSEL

SIGN• Small pulmonary artery is seen leading directly to a

nodule

• Most common with metastasis, infarct, and

arteriovenous fistula.

• Less common with primary lung carcinoma or

benign lesions such as granuloma.

Metastatic nasopharyngeal carcinoma.

Multiple nodules (arrows) are associated

with a feeding vessel.

FAT

• The presence of fat in an SPN may be diagnosed accurately only on HRCT.

• On HRCT, fat can be accurately diagnosed if low CT numbers are seen (-40 to -120 HU)..

• The presence of fat within a lung nodule is sufficient for calling it benign, although follow-up is appropriate.

HAMARTOMA

LIPOMA

LIPOID PNEUMONIA

TERATOMA

LIPOSARCOMA

RCC

Hamartomas containing fat in three patients. Focal areas

of low-attenuation fat are visible within the nodules

(arrows). The nodules are rounded and sharply defined

WATER

DENSITY• Benign cystic lesions, such as pulmonary

bronchogenic cyst, sequestration, congenital cystic

adenomatoid malformation (CCAM), or a fluid-filled

cyst or bulla , occasionally may be diagnosed on CT

by their water attenuation (0 HU)

Pulmonary bronchogenic cyst. A sharply marginated

round nodular opacity (arrow) is visible in the right

lower lobe. This measured 0 HU in attenuation. This

appearance is typical of a fluid-filled bronchogenic

cyst

CONTRAST

ENHANCEMENT• Cancers have a greater tendency to opacify following

contrast infusion than do some types of benign

nodules

• One currently recommended protocol uses scans at

1 minute intervals for 4 minutes following the start of

the injection of 420 mg iodine/kg (usually 75 to 125

mL) at a rate of 2 mL/sec.

• A region of interest encompassing about 60% of the

nodule diameter is used to measure enhancement

Nodule enhancement of <15 HU after administration of

contrast material is strongly indicative of benignity (positive

predictive value,approximately99%).

Rare false-negative findings are associated with central

noncavitating necrosis and adenocarcinomas (especially

bronchioloalveolar cell carcinoma), which may be related to

mucin production

Although enhancement of more than15 HU is more likely to

represent malignancy, only 58% of nodules are malignant; the

remainder represent enhancing lesions due to active

inflammatory disease that have increased blood flow, such as

granulomas or organizing pneumonias .

Enhancing nodules should still be considered indeterminate

and require further workup.

In summary, nodulebehavior after contrast material

administration is sensitive but not specificfor malignancy.

CT enhancement study in a 54-year-old woman with endometrial

hyperplasia. CT images obtained before (a) and after (b)

administration of intravenous contrast material show the

nodule has enhanced, with an increase in attenuation values of

109 HU.

CONTRAST

OPACIFICATION Some solitary (or multiple) lesions opacify following

contrast injection, thus representing vascular

structures .

Arteriovenous malformation

Pulmonary vein varix

Pulmonary artery aneurysm

HEMODYNAMICS• Can be assessed by helical dynamic CT by wash in

& wash out of contrast

• Diagnostic criteria indicated a malignant nodule:

≥ 25 H wash-in and 5–31 H washout

lobulated margin

spiculated margin

absence of a satellite nodule

Metastatic adenocarcinoma in 57-year-old man with rectal cancer

shows net enhancement of ≥ 25H and washout of 5–31 H on

dynamic helical CT

GROWTH RATE• Determination of growth rate by comparing sizes

on current and prior images is an important and

cost-effective step in the evaluation of SPNs.

• For radiographic measurement, the nodule

diameter is measured in atleast two dimensions

and averaged on two serial images.

• Doubling time (Td) is calculated with the following

equation

Td = Ti * log 2/3 * log(Di/Do),

Ti interval time, Di initial diameter & Do final

diameter.

The time for a nodule to double in volume is

referred to as the doubling time.

• A pulmonary nodule that doubles in volume in less than 1 month or more than 200 days is very likely benign.

• Slower-growing lesions often are benign tumors or granulomas. More rapidly growing lesions usually are inflammatory

• For most of malignancies doubling time is 30-400 days.

• 30 days for small cell carcinoma,

• 100 days for squamous cell and large cell carcinoma,

• 180 days for adenocarcinoma.

• LIMITATIONS: It is difficult to reliably detect growth

in small (< 1cm) nodules

• For subsolid nodules, the limitations in assessing

growth are compounded because they are typically

small & poorly defined with growth that may be

indolent and difficult to perceive.

• In contrast to growth in solid nodules, which is

based solely on size, in subsolid nodules, growth

may manifest as an increase in size, an increase in

attenuation, development of a solid component, or

an increase in size of a solid component. In

subsolid nodules, these imaging features of growth

indicate an increased risk for malignancy

• It has been suggested that the use of 3d volumetric

assessment, rather than diameter, is a more

accurate and reproducible method for determining

the size and growth of solid and subsolid SPNs .

• However, there is considerable controversy

regarding the most accurate method for assessing

the growth rate of solid and subsolid nodules.

• Recently mass was proposed as a more accurate

determinant of growth of subsolid nodules. CT data

may be used to calculate mass because x-ray

attenuation values are proportional to tissue density

(ie, mass per unit volume)

11 a. Coned-down CT image of the chest with coronal reformation shows a 1.2-

cm subsolid nodule (arrow) in the left upper lobe. (b) Follow-up CT image

obtained 1 year later shows the nodule (arrow), which demonstrates increased

attenuation, in addition to an increase in the overall size.

12 . (a) Contrast-enhanced CT image shows a 1.8-cm nodule with pure ground-

glass attenuation (arrow) in the left upper lobe. (b) Follow-up CT image

obtained 3 months later shows the nodule (arrow), with a new solid component

posteriorly (arrowhead). Biopsy was performed, and results of histologic

analysis revealed adenocarcinoma.

UNUSUAL PATTERNS OF GROWTH

• Isolated cystic airspace with increased wall

thickness should raise the suspicion of lung

cancer.

• Although most lung cancers grow at a steady

exponential rate, a temporary regression in growth

can occur which may be related to the

development of a fibrous component and

subsequent collapse of the fibrosis.

• Accordingly, a decrease in nodule size requires

continued imaging reassessment to confirm long-

term stability or resolution

Lung cancer manifesting with increased wall thickness of a cystic airspace

in a 77-year-old man with a history of right upper lobectomy for

adenocarcinoma. (a) Contrast-enhanced CT image shows a cystic airspace

(*) in the right lower lobe. (b) Follow-up CT image obtained 6 months later

shows a new soft-tissue component (arrows) along the wall of the cystic

airspace. Results of histologic analysis of the soft-tissue component

revealed adenocarcinoma.

Transient decrease in size of a lung cancer. (a) CT image obtained at the

patient’s initial presentation shows a nodule (arrow) in the left lower lobe.

(b) Follow-up CT image obtained 1 year later shows the nodule (arrow),

which decreased in size. (c) CT image obtained 2 years after the initial

presentation shows the nodule (arrow), which increased in size and

lobularity.

FDG-PET

• Its diagnostic ability is based on increased glucose consumption of malignant cells.

• PET is obtained by injecting 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (FDG).

• FDG is a D-glucose analog labeled with a positron emitter (18F) that is transported through the cell membrane and phosphorylated using normal glycolytic pathways.

• The degree of FDG accumulation is measured using the standardized uptake ratio (SUR); the SUR of lung cancers usually is more than 2.5.

• FDG-PET has a sensitivity of about 95% in detecting malignant SPNs 1 cm or more in diameter, with a specificity of about 80%

• Determination of the utility of FDG PET for evaluating

SPNs takes into consideration clinical risk factor and

imaging features to determine a management course.

• For eg: patient with a low pretest likelihood (20%) of

malignancy who is being considered for serial imaging

reassessment, negative findings at PET reduce the

likelihood of malignancy to 1%, favoring conservative

management (72). However, in a patient with a high

pretest likelihood (80%) of malignancy, negative findings

at PET only reduce the likelihood of malignancy to 14%;

thus, a more aggressive course of action may be

considered, such as obtaining tissue for biopsy or

resection

FDG-PET in a patient with adenocarcinoma. A. HRCT shows a small right

upper lobe nodule (arrow). B. PET (coronal plane) shows the nodule to have

a very high activity (arrow). The size of the nodule on PET exceeds its real

size. PET is poor at showing the specific location of abnormalities.

• False positive : inflammatory lesions.

• False-negative : carcinoid tumor ,bronchioloalveolar

carcinoma, and lesions smaller than 1 cm.

• Radionuclide single-photon emission computed

tomography (SPECT) employing depreotide (a

somatostatin analogue), thallium, or FDG also may

be used to diagnose malignancy in a large lung

nodule but is less sensitive than PET for nodules

smaller than 2 cm.

Infection mimicking malignancy in a 30- year-old man with no symptoms

and a right lower lobe mass detected at chest radiography performed for

a routine occupational health examination. (a, b) Unenhanced CT (a) and

PET/CT (b) images show a 3-cm solid lesion in the right lower lobe

(arrow in a) with a maximum SUV of 16.7. Biopsy results revealed

granulomatous inflammation and no malignant cells. (c) Follow-up CT

image obtained 2 months later shows regression of the lesion (arrow).

Infectious and inflammatory conditions can accumulate FDG and be

misinterprete

PET-negative neuroendocrine tumor in a 59-year-old woman.

Unenhanced CT (a) and PET/CT (b) images show a well-

circumscribed nodule in the middle lobe (arrow) with no FDG

uptake. Results from transthoracic needle biopsy revealed a

well-differentiated neuroendocrine tumor (carcinoid).

INTEGRATED PET/CT

SCAN• Provides both morphological & metabolic features at

the same time.

PET (left) and integrated PET/CT (right) images show maximum

standardized uptake value (SUV) of 8.8 in primary nodule

(arrow) in right upper lobe.

BIOPSY

• Various approaches include

Fiberoptic bronchoscopy (FOB),

Transthoracic needle biopsy (TNB),

Video-assisted thoracoscopic surgery(VATS)

• Fiberoptic bronchoscopy-

Limited role

Accurate for assessing endobronchial lesions,

The yield for peripheral nodules is < 60%, and is

only 25% to 30% for an SPN smaller than 2 cm

Best when a bronchus leads directly to or is seen

within the SPN (the “positive bronchus” sign).

Transthoracic Needle Biopsy:

• The sensitivity of TNB in diagnosing cancer is over 90%.

• The accuracy of TNB for diagnosing benign disease other than active infections is limited.

• Biopsy of nodules smaller than 1 cm in diameter is associated with an increased false-negative rate.

• Complications include

Pneumothorax,

Hemorrhage,

Air embolism

DYNAMIC MAGNETIC RESONANCE

IMAGING

• Perfusion differences in malignant and benign

lesions were compared.

• Dynamic MR images were acquired every 10

seconds for a total of 4 minutes-T1-weighted in-

phase two-dimensional gradient-echo MR

sequence.

• Diagnostic characteristics for differentiation were

examined by using threshold values for maximum

peak enhancement and washout.

• The mean relative enhancement ratio and mean

slope of enhancement for the malignant SPN group

were significantly higher than those for the benign

SPN group and significantly lower than those for

the active infection group

• Significant washout was found only in malignant

lesions.

• Sensitivity, specificity, and accuracy were 96%,

88%, and 92%, respectively, for maximum peak;

and 52%, 100%, and 75% for washout.

Times after bolus injection of contrast material were 9.9

seconds (left), 11.0 seconds (middle), and 18.7 seconds

(right). Lesion diameter was 25 mm;, maximum relative

enhancement ratio, 0.68; and slope of enhancement,

0.077/sec.

Adenocarcinoma

tuberculoma

Times after bolus injection of contrast material were 0 seconds

(left), 12.1 seconds (middle), and 23.1 seconds (right). Lesion

diameter was 11 mm; maximum relative enhancement ratio,

0.04; and slope of enhancement, 0.0036/sec.

DIFFUSION WEIGHTED

MRI• The signal intensity of pulmonary nodules may be

useful for malignant and benign differentiation on DWI when a high b factor of 1,000 s/mm2 is used using a 5-point rank scale.

This scale was based on the following scores:

1.nearly no signal intensity;

2. signal intensity between

3.signal intensity almost equal to that of the thoracic spinal cord

4. higher signal intensity than that of the spinal cord; and

5. much higher signal intensity than that of the spinal cord.

• When a score of 3 was considered as a threshold,

the sensitivity, specificity, and accuracy were 88.9%,

61.1%, and 79.6% respectively.

• However, the interpretation of small metastatic

nodules,nonsolid adenocarcinoma, some

granulomas, and active inflammatory nodules

should be approached with caution.

a. Transverse T1-weighted image (TR/TE, 150/4.6)shows mass (arrow) in right

upper lobe.

b. Transverse diffusion-weighted (DW) echo-planar image (3,084/70) obtained

with b factor of 1,000 s/mm2 shows mass (arrow) with very high signal intensity

compared with spinal cord; it scored 5 on 5-point rank scale. Spinal cord scored 3

on 5-point

rank scale on DW images obtained with b factor of 1,000 s/mm2.

A. Coronal T1-weighted image (TR/TE, 119/4.6) shows mass (arrow) in right lower

lobe.

B.Transverse diffusion-weighted (DW) image(4,654/70) obtained with b factor of

1,000 s/mm2 shows mass (arrow) with slightly lower signal intensity compared with

spinal cord; it scored 2 on 5-point rank scale. Spinal cord scored 3 on 5-point rank

scale on DW images obtained with b factor of1,000 s/mm2.

FOLLOW UP

ALGORITHIM• When performing CT for follow up attention to

radiation dose is important

• Dose savings may be achieved with the use of widely available tube current modulation techniques that serve as a form of automatic exposure control; the tube current is adjusted for overall patient size and varies, while CT data are acquired in the axial and longitudinal directions to maintain homogeneous image quality.

• Higher tube current is delivered to thicker and denser areas of the body, and lower tube current is delivered to the remaining areas.

• Typical reconstructions consist of 2.5 mm and thicker sections for a nontargeted field of view. The use of thin sections (1.0–1.5 mm) in the region of interest improves z-axis spatial resolution

FLEISCHNER SOCIETY GUIDELINES FOR THE

EVALUATION OF

INCIDENTALLY DISCOVERED NODULES(SOLID

SPN)

NODUL

E SIZE

LOW RISK PATIENTS HIGH RISK PATIENTS

≤4 mm NO REASSESSMENT NECESSARY REASSESSMENT AT 12 MONTHS; IF STABLE,

NO FURTHER EVALUATION REQUIRED.

THE EXCEPTION IS A NONSOLID OR

PARTIALLY

SOLID NODULE, FOR WHICH REASSESSMENT

MAY BE REQUIRED TO EXCLUDE THE RISK OF

INDOLENT ADENOCARCINOMA

>4 mm but

≤6 mm

REASSESSMENT CT AT 12

MONTHS; IF

STABLE, NO FURTHER

EVALUATION REQUIRED. THE

EXCEPTION IS A

NONSOLID OR PARTIALLY SOLID

NODULE, FOR WHICH

REASSESSMENT MAY BE

REQUIRED TO EXCLUDE THE RISK

OF INDOLENTADENOCARCINOMA

REASSESSMENT CT AT 6 TO 12 MONTHS

AND, IF STABLE, AGAIN AT 18 TO 24 MONTHS

>6 mm but

≤8 mm

REASSESSMENT CT AT 6 -

12MONTHS

AND, IF STABLE, AGAIN AT 18 TO

24 MONTHS

REASSESSMENT CT AT 3 TO 6 MONTHS

AND, IF STABLE, AGAIN AT 9 TO 12 MONTHS

AND AT 24 MONTHS

>8 mm: EITHER REASSESSMENT CT

SCANS AT 3, 9, AND 24 MONTHS TO

ASSESS FOR STABILITY IN SIZE

EITHER REASSESSMENT CT SCANS AT 3, 9,

AND 24 MONTHS TO ASSESS FOR STABILITY

IN SIZE OR FURTHER EVALUATION WITH

Source/Reference

Factors Taken Into Consideration to

Determine the Probability of

Malignancy

www.chestx-ray.com 1. Age

2. Smoking (ever vs never and pack-

y)

3. Hemoptysis

4. History of prior malignancy

5. Nodule diameter

6. Location

7. Edge characteristics

8. Growth rate

9. Cavity wall thickness

10. Calcifi cation

11. Contrast enhancement on CT

scan .15 HU

12. PET scan

Swensen et al 26 1. Age

2. Smoking history (ever vs never)

3. History of previous malignancy . 5

y ago

4. Presence of spiculation

5. Upper lobe location

Gould et al 27 1. Age

2. Smoking history (ever vs never)

BAYESIAN

ANALYSIS• Analysis of patient characteristics & selected

radiological features.

• LR = NUMBER OF MALIGNANT NODULES

NUMBER OFBENIGN NODULES

• LRs less than 1.0 typically indicate benign

lesions, whereas LRs greater than 1.0 typically

indicate malignancy.

• Odds of malignancy=sum of LR of radiological

features or patient characteristics

• Probability of malignancy (pCa) = Odds ca

1 +Odds ca

DECISION

ANALYSIS• Based on pCa

pCa

<0.05 – observation

>0.05<0.6 - biopsy

>_0.6 - surgery

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