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ABR practice questions

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Question 1Breast imaging

A screening mammogram shows a possible asymmetry that cannot be characterized without additional views. Which BI-RADS assessment category is assigned at this point?

  1. BI-RADS 0 Correct answer.
  2. BI-RADS 3
  3. BI-RADS 4
  4. BI-RADS 2

Explanation

BI-RADS 0 is an incomplete assessment used when additional imaging (extra views, ultrasound, magnification) or comparison with prior studies is needed before a final category can be given. It is never a final diagnosis and always mandates a follow-up action.

Question 2Breast imaging

According to the American College of Radiology, at what age should average-risk women begin annual screening mammography?

  1. 50 years
  2. 45 years
  3. 40 years Correct answer.
  4. 30 years

Explanation

The ACR recommends annual screening mammography beginning at age 40 for women at average risk, with no upper age limit based on age alone. Earlier initiation is reserved for women at markedly elevated risk.

Question 3Breast imaging

In which quadrant of the breast do the majority of breast cancers arise?

  1. Lower outer
  2. Upper outer Correct answer.
  3. Lower inner
  4. Upper inner

Explanation

The upper outer quadrant contains the largest volume of glandular tissue and gives rise to roughly half of all breast cancers. The retroareolar region and upper inner quadrant follow in frequency.

Question 4Breast imaging

Which ultrasound description best characterizes a classic fibroadenoma?

  1. Taller-than-wide hypoechoic mass with spiculated margins
  2. Oval circumscribed hypoechoic mass with parallel orientation Correct answer.
  3. Ill-defined hypoechoic mass with an echogenic halo and marked posterior shadowing
  4. Irregular hypoechoic mass with posterior acoustic shadowing

Explanation

Fibroadenomas are benign fibroepithelial lesions that appear as oval, circumscribed, homogeneous hypoechoic masses that are wider than tall (parallel to the skin). Shadowing, spiculation, and a taller-than-wide shape are features of malignancy.

Question 5Breast imaging

Which mammographic calcification pattern is considered benign and generally requires no further workup?

  1. Fine pleomorphic calcifications grouped in a cluster
  2. Diffuse punctate calcifications Correct answer.
  3. Amorphous calcifications in a segmental distribution
  4. Fine linear branching calcifications

Explanation

Diffuse punctate calcifications are scattered throughout the breast and are a benign, BI-RADS 2 finding. Clustered pleomorphic, amorphous, and linear branching calcifications all raise suspicion for ductal carcinoma in situ and require biopsy.

Question 6Breast imaging

Compared with conventional 2D digital mammography, which benefit is best supported for digital breast tomosynthesis in population screening?

  1. Superior performance for evaluating axillary lymphadenopathy and internal mammary nodes
  2. Elimination of the need for additional imaging in women with dense breasts
  3. Substantially lower radiation dose to the breast for each examination
  4. Higher cancer detection rate with fewer recall examinations Correct answer.

Explanation

Population studies and trials show tomosynthesis increases cancer detection, particularly of invasive cancers, while lowering recall rates relative to 2D mammography. Radiation dose is slightly higher, and additional imaging is still often needed.

Question 7Breast imaging

Which statement about mammographic breast density is most accurate?

  1. Density matters only for technical exposure and dose calculations
  2. It is an independent risk factor and lowers mammographic sensitivity Correct answer.
  3. Density lowers breast cancer risk because fat is metabolically active
  4. Density affects neither mammographic sensitivity nor breast cancer risk

Explanation

Dense fibroglandular tissue both masks cancers on mammography and is itself an independent risk factor for breast cancer. Its effect on risk persists after adjustment for age and other risk factors.

Question 8Breast imaging

A 30-year-old woman is known to carry a BRCA1 mutation and has never been screened. Which screening regimen is recommended?

  1. Biennial mammography beginning at age 50
  2. Annual ultrasound alone beginning now, with mammography added at age 50
  3. Annual MRI plus mammography starting at about age 30 Correct answer.
  4. Annual mammography alone, with the first study deferred until age 40

Explanation

Women with BRCA1 or BRCA2 mutations should begin annual breast MRI, usually with mammography, at around age 25 to 30. MRI has the highest sensitivity in this high-risk group because BRCA-associated cancers often appear in dense breasts.

Question 9Breast imaging

A 58-year-old man reports unilateral subareolar tenderness. Mammography shows a flame-shaped subareolar density without a discrete mass or calcifications. What is the most appropriate interpretation?

  1. Suspicious for male breast cancer, BI-RADS 4C
  2. Normal male breast, with no reportable finding
  3. Incomplete study requiring breast MRI
  4. Benign gynecomastia, BI-RADS 2 Correct answer.

Explanation

A flame-shaped or dendritic subareolar density in a symptomatic man represents gynecomastia, a benign finding reported as BI-RADS 2. Male breast cancer typically appears as a discrete, often eccentric subareolar mass that may contain calcifications.

Question 10Breast imaging

Which statement about Paget disease of the breast is correct?

  1. It is characterized by bilateral reticular pigmentation, crusting, and scaling of both areolae
  2. It almost always presents with a palpable axillary mass and peau d'orange
  3. It usually overlies DCIS or invasive carcinoma and may have a normal mammogram Correct answer.
  4. It is a primary skin cancer of the nipple that arises independently of any underlying breast tissue

Explanation

Paget disease of the nipple represents epidermal extension of underlying ductal carcinoma in situ or invasive carcinoma. Mammography is normal in a substantial proportion of cases, so clinical suspicion requires nipple biopsy.

Question 11Breast imaging

Which breast carcinoma is most likely to be occult on mammography and best depicted on MRI?

  1. Invasive ductal carcinoma, no special type
  2. Invasive lobular carcinoma Correct answer.
  3. Mucinous carcinoma
  4. Medullary carcinoma

Explanation

Invasive lobular carcinoma infiltrates in single-file cords without provoking a desmoplastic reaction, so it often produces no discrete mass or architectural distortion on mammography. MRI is the most sensitive modality for defining its extent.

Question 12Breast imaging

A screening mammogram shows a cluster of amorphous calcifications. The area is not visible on targeted ultrasound. What is the most appropriate next step?

  1. Stereotactic vacuum-assisted core biopsy Correct answer.
  2. Six-month follow-up mammography
  3. Short-interval contrast-enhanced MRI of the breast
  4. Fine-needle aspiration under ultrasound guidance

Explanation

Suspicious calcifications without a sonographic correlate must be sampled under mammographic guidance, typically stereotactic or tomosynthesis-guided vacuum-assisted core biopsy. Ultrasound guidance cannot be used for a lesion that ultrasound does not show.

Question 13Breast imaging

Six months after a seatbelt injury, a woman has a palpable lump. Mammography shows a circumscribed lucent, fat-containing mass with a thin rim of calcification. What is the most likely diagnosis?

  1. Fibroadenoma with coarse popcorn calcification
  2. Invasive ductal carcinoma
  3. Fat necrosis with an oil cyst Correct answer.
  4. Phyllodes tumor

Explanation

A fat-containing mass with a thin calcific rim following trauma is an oil cyst, a form of fat necrosis, and is a benign BI-RADS 2 finding. The lucent center confirms fat, which excludes a solid neoplasm.

Question 14Breast imaging

A 45-year-old woman has spontaneous bloody discharge from a single duct. Ultrasound shows a small intraductal mass. What is the most appropriate management?

  1. Tissue diagnosis, typically by duct excision or core biopsy Correct answer.
  2. Reassurance alone, because spontaneous bloody discharge is almost always benign
  3. Prophylactic bilateral mastectomy
  4. Repeat mammography in 12 months without further workup

Explanation

Spontaneous bloody single-duct discharge with an associated intraductal mass requires tissue sampling to exclude a papilloma with atypia or an underlying carcinoma. Duct excision or image-guided core biopsy is appropriate.

Question 15Breast imaging

A 45-year-old woman has a rapidly enlarging 6 cm mass. Ultrasound shows a heterogeneous, lobulated mass with cleft-like cystic spaces, and core biopsy indicates a fibroepithelial lesion. What is the best next step?

  1. Surgical excision with adequate margins Correct answer.
  2. Repeat core biopsy to obtain additional tissue for grading
  3. Observation with repeat ultrasound in 6 months
  4. Neoadjuvant chemotherapy followed by mastectomy

Explanation

Rapid growth with a heterogeneous, clefted appearance suggests a phyllodes tumor, which can mimic a fibroadenoma on core biopsy because of sampling. Complete surgical excision with negative margins is required, as core biopsy may underestimate grade.

Question 16Breast imaging

Which breast cancer subtype is most strongly associated with BRCA1 mutations and frequently presents as an interval cancer between screening rounds?

  1. Triple-negative (basal-like) Correct answer.
  2. Luminal B, HER2-negative
  3. Luminal A
  4. HER2-enriched

Explanation

Triple-negative, basal-like cancers are overrepresented among BRCA1 carriers and grow rapidly, so they often emerge between annual screening examinations. Their rapid growth and lack of a mammographic mass in dense tissue contribute to interval presentation.

Question 17Breast imaging

In screening mammography, overdiagnosis refers to which of the following?

  1. A cancer that would never have caused symptoms in the patient's lifetime Correct answer.
  2. A false-positive result that leads to an unnecessary benign core needle biopsy
  3. A tumor found at a smaller size than clinical detection would yield
  4. A recalled screening examination that is repeated because of technical failure or poor positioning

Explanation

Overdiagnosis is the detection of a cancer that would not have become clinically apparent during the patient's remaining lifetime, leading to treatment without benefit. It is distinct from false-positive recalls and from the beneficial effect of downstaging.

Question 18Cardiovascular imaging

In a right-dominant coronary system, the posterior descending artery most commonly arises from which vessel?

  1. Right coronary artery Correct answer.
  2. Left main coronary artery
  3. Left anterior descending artery
  4. Left circumflex artery

Explanation

In roughly 85% of people the circulation is right dominant, meaning the posterior descending artery originates from the distal right coronary artery at the crux of the heart. Left dominance, in which the posterior descending artery arises from the circumflex, is seen in a minority of patients.

Question 19Cardiovascular imaging

Which late gadolinium enhancement pattern on cardiac MRI is most characteristic of an ischemic scar?

  1. Patchy mid-wall enhancement of the lateral wall
  2. Global epicardial enhancement of both ventricles
  3. Diffuse enhancement with early blood pool nulling
  4. Subendocardial or transmural enhancement in a coronary territory Correct answer.

Explanation

Ischemic injury begins in the subendocardium and extends outward, so scar follows a vascular territory and always involves the subendocardium. Nonischemic patterns such as mid-wall or epicardial enhancement spare the subendocardium and do not respect coronary boundaries.

Question 20Cardiovascular imaging

A coronary artery calcium score of zero on a noncontrast cardiac CT indicates which of the following?

  1. Mild noncalcified stenosis cannot be excluded by any means
  2. Severe multivessel disease is present
  3. Zero calcium with very low likelihood of obstruction Correct answer.
  4. Moderate risk warranting invasive angiography

Explanation

The Agatston score quantifies calcified plaque, and a score of zero confers a very low short-term risk of obstructive coronary disease and cardiac events. Because noncalcified plaque is not detected, a zero score does not exclude noncalcified atherosclerosis entirely, but the likelihood of flow-limiting stenosis is low.

Question 21Cardiovascular imaging

Which radiotracer is used with PET to assess myocardial glucose metabolism for viability?

  1. Nitrogen-13 ammonia
  2. Thallium-201 chloride
  3. Fluorine-18 fluorodeoxyglucose Correct answer.
  4. Technetium-99m sestamibi

Explanation

Fluorine-18 fluorodeoxyglucose is a glucose analog taken up by metabolically active myocardium, so preserved uptake in a region with a perfusion defect indicates hibernating viable tissue. Sestamibi, thallium, and ammonia are perfusion agents rather than markers of glucose metabolism.

Question 22Cardiovascular imaging

Global longitudinal strain on echocardiography is most commonly derived using which technique?

  1. Two-dimensional speckle tracking Correct answer.
  2. Contrast opacification of the left ventricular cavity
  3. Doppler tissue velocity of the mitral annulus
  4. Three-dimensional reconstruction of the left atrium

Explanation

Speckle tracking follows the movement of acoustic markers within the myocardium across the cardiac cycle to compute deformation in each segment. Strain is more sensitive than ejection fraction for detecting early systolic dysfunction, such as in cardiotoxicity surveillance.

Question 23Cardiovascular imaging

A dissection flap is seen on CT angiography extending from the aortic root through the arch. This finding defines which classification?

  1. Involvement of the ascending aorta Correct answer.
  2. Intramural hematoma limited to the arch
  3. Isolated dissection of the abdominal aorta
  4. Dissection confined to the descending aorta distally

Explanation

The Stanford system classifies any dissection involving the ascending aorta as type A, regardless of the extent of distal involvement, because of the risk of coronary, pericardial, and arch vessel complications. Type B dissections spare the ascending aorta and originate distal to the left subclavian artery.

Question 24Cardiovascular imaging

Which late gadolinium enhancement finding on cardiac MRI is most typical of cardiac amyloidosis?

  1. Patchy mid-wall enhancement of the basal septum
  2. Subendocardial enhancement limited to the LAD territory
  3. Transmural enhancement confined to the apex
  4. Diffuse subendocardial enhancement with abnormal myocardial nulling Correct answer.

Explanation

Amyloid deposition expands the extracellular space, producing diffuse subendocardial or transmural enhancement and altering gadolinium kinetics so that the blood pool nulls before the myocardium. This abnormal nulling pattern is a hallmark that distinguishes amyloidosis from other cardiomyopathies.

Question 25Cardiovascular imaging

On CT pulmonary angiography, which measurement best indicates right ventricular dysfunction in acute pulmonary embolism?

  1. RV/LV diameter ratio greater than 1 Correct answer.
  2. Bilateral pleural effusions
  3. Left ventricular hypertrophy
  4. Main pulmonary artery diameter under 20 mm

Explanation

An increased right-to-left ventricular diameter ratio on reconstructed four-chamber or axial images reflects acute right ventricular pressure overload and correlates with adverse outcomes. It is used together with clinical scoring to guide decisions about thrombolysis or closer monitoring.

Question 26Cardiovascular imaging

Which condition is characteristically associated with a low native myocardial T1 relaxation time at 1.5 T?

  1. Hypertrophic cardiomyopathy
  2. Cardiac amyloidosis
  3. Acute myocarditis
  4. Anderson-Fabry disease Correct answer.

Explanation

Sphingolipid accumulation in Anderson-Fabry disease lowers native myocardial T1, which helps distinguish it from other causes of left ventricular hypertrophy. In contrast, conditions that expand the extracellular space or cause edema raise native T1.

Question 27Cardiovascular imaging

A patient undergoing adenosine stress perfusion MRI develops subendocardial hypoperfusion in the inferolateral wall during stress that resolves on the rest images. What does this indicate?

  1. Reversible ischemia in the territory supplied by that artery Correct answer.
  2. Artifact from the dark-rim effect
  3. Fixed scar from a prior infarction
  4. Global subendocardial ischemia from microvascular disease

Explanation

A perfusion defect that appears with vasodilator stress and reverses at rest reflects a flow-limiting stenosis in the supplying coronary artery. Infarction, by contrast, produces a defect that persists on both stress and rest acquisitions.

Question 28Cardiovascular imaging

During CT planning for transcatheter aortic valve replacement, which measurement is most important for prosthesis sizing?

  1. Left ventricular ejection fraction
  2. Coronary artery calcium score
  3. Ascending aortic diameter at the sinotubular junction
  4. Annulus area and perimeter-derived diameter Correct answer.

Explanation

Prosthesis size is selected from the aortic annulus area and perimeter measured on a double-oblique reconstruction, because the annulus is oval and diameter alone underestimates its size. Undersizing causes paravalvular leak and oversizing risks annular rupture.

Question 29Cardiovascular imaging

Low-dose dobutamine stress echocardiography is performed in a patient with low-flow, low-gradient aortic stenosis and reduced ejection fraction primarily to do which of the following?

  1. Assess contractile reserve and true stenosis severity Correct answer.
  2. Exclude associated infective endocarditis
  3. Quantify concomitant aortic regurgitation
  4. Measure the left atrial volume index

Explanation

When the gradient is low because of poor flow, dobutamine increases flow and reveals whether the stenosis is truly severe or only pseudosevere. An increase in stroke volume with a rise in gradient identifies contractile reserve, which carries a better prognosis after intervention.

Question 30Cardiovascular imaging

A myocardial perfusion SPECT study shows a defect in the inferior wall that is unchanged between stress and rest images. What is the most likely interpretation?

  1. Reversible ischemia in the right coronary territory
  2. Technical artifact from patient motion
  3. Myocardial scar or infarction Correct answer.
  4. Normal variant related to breast attenuation

Explanation

A defect of equal severity on stress and rest images represents a fixed perfusion abnormality, which corresponds to infarcted or scarred myocardium. Ischemia produces a defect that is larger or more intense at stress and improves at rest.

Question 31Cardiovascular imaging

Which cardiac MRI finding supports the diagnosis of arrhythmogenic right ventricular cardiomyopathy?

  1. Diffuse pericardial thickening with a moderate effusion
  2. Late gadolinium enhancement confined to the lateral left ventricular wall
  3. Symmetric left ventricular hypertrophy with apical sparing
  4. Regional RV wall motion abnormality with RV dilation Correct answer.

Explanation

Arrhythmogenic right ventricular cardiomyopathy is characterized by fibrofatty replacement of the right ventricular myocardium, producing regional akinesia or dyskinesia, right ventricular dilation, and fatty infiltration. These structural changes are major diagnostic criteria in the revised Task Force scheme.

Question 32Cardiovascular imaging

On cardiac FDG-PET in a patient with suspected cardiac sarcoidosis, focal FDG uptake in a region that shows a resting perfusion defect most likely represents which of the following?

  1. Hepatic uptake artifact from inadequate fasting
  2. Prior infarction with transmural scar
  3. Normal myocardial glucose utilization
  4. Active granulomatous inflammation Correct answer.

Explanation

Focal or focal-on-diffuse FDG uptake in a segment with reduced perfusion reflects inflammation in a region of injured but still metabolically active myocardium. A matched perfusion-metabolism defect, by contrast, would indicate scar without active inflammation.

Question 33Cardiovascular imaging

CT-derived fractional flow reserve estimates the hemodynamic significance of a stenosis by combining anatomic stenosis data with which of the following?

  1. Modeled hyperemic flow and myocardial mass Correct answer.
  2. Coronary calcium score of the target vessel
  3. Contrast opacification of the coronary sinus
  4. Left ventricular myocardial wall thickness

Explanation

CT-derived FFR applies computational fluid dynamics to the coronary tree under simulated hyperemic conditions, with flow demand scaled to the myocardial mass subtended by each vessel. This allows lesion-specific physiologic assessment without an invasive pressure wire.

Question 34Cardiovascular imaging

Phase-contrast MRI in a patient with a ventricular septal defect yields a pulmonary-to-systemic flow ratio of 1.8. What does this value indicate?

  1. A hemodynamically significant left-to-right shunt Correct answer.
  2. A right-to-left shunt causing cyanosis
  3. No net shunt across the defect
  4. Pulmonary hypertension disproportionate to shunt flow

Explanation

A Qp/Qs ratio above 1.5 indicates a left-to-right shunt large enough to be considered hemodynamically significant and potentially worthy of closure. Values near 1.0 indicate no meaningful shunt, and a ratio below 1.0 indicates net right-to-left flow.

Question 35Gastrointestinal imaging

A 45-year-old man reports 1 year of progressive dysphagia that occurs with both solids and liquids. Barium esophagram shows a dilated esophageal body with smooth, symmetric tapering at the gastroesophageal junction. What is the most likely diagnosis?

  1. Diffuse esophageal spasm
  2. Esophageal carcinoma
  3. Scleroderma esophagus
  4. Achalasia Correct answer.

Explanation

Achalasia produces a dilated aperistaltic esophageal body with smooth symmetric narrowing at the gastroesophageal junction (the 'bird's beak'), and dysphagia involves liquids as well as solids from early in the course. These features reflect failure of lower esophageal sphincter relaxation with loss of myenteric ganglion cells.

Question 36Gastrointestinal imaging

A 3 cm lesion in the right hepatic lobe shows discontinuous peripheral nodular enhancement on the arterial phase that progressively fills toward the center on delayed images, matching blood pool signal. What is the most likely diagnosis?

  1. Focal nodular hyperplasia
  2. Hepatocellular carcinoma
  3. Hepatic hemangioma Correct answer.
  4. Metastasis

Explanation

Peripheral nodular enhancement with centripetal progressive fill-in that follows blood pool signal is the classic signature of a hepatic hemangioma, reflecting slow filling of large vascular spaces. This pattern is highly specific and typically requires no further workup in a non-cirrhotic patient.

Question 37Gastrointestinal imaging

Which CT finding is the primary criterion used to diagnose acute appendicitis?

  1. Appendicolith
  2. Appendix >6 mm with wall thickening Correct answer.
  3. Periappendiceal fat stranding alone
  4. Cecal wall thickening

Explanation

The diagnostic cornerstone is an abnormally distended, fluid-filled appendix greater than 6 mm in diameter with wall thickening and enhancement, usually accompanied by adjacent fat stranding. Diameter plus wall changes carries far higher specificity than any single secondary sign.

Question 38Gastrointestinal imaging

A 60-year-old man has sudden severe abdominal pain and rigidity. Which finding on an upright chest radiograph most directly indicates pneumoperitoneum?

  1. Basal pleural effusion
  2. Crescent of free gas under the diaphragm Correct answer.
  3. Gastric air-fluid level with distension
  4. Pneumatosis intestinalis

Explanation

Free intraperitoneal gas rises to the nondependent subdiaphragmatic space on an upright view, producing a thin crescent of lucency between the diaphragm and liver or stomach. This is the most direct plain-film sign of perforation and prompts urgent surgical evaluation.

Question 39Gastrointestinal imaging

Which CT finding most reliably distinguishes mechanical small bowel obstruction from generalized ileus?

  1. Diffuse dilatation of small and large bowel
  2. Uniform bowel wall thickening
  3. Transition point with proximal dilatation Correct answer.
  4. Air-fluid levels on supine images

Explanation

Mechanical obstruction produces a discrete transition point where dilated proximal bowel abruptly decompresses into collapsed distal bowel. Ileus instead shows proportional dilatation of small and large bowel without a focal transition.

Question 40Gastrointestinal imaging

A 60-year-old man with hepatitis C cirrhosis has a 2.5 cm lesion with arterial phase hyperenhancement, portal venous washout, and a delayed enhancing capsule on MRI. What is the most likely diagnosis?

  1. Hepatocellular carcinoma Correct answer.
  2. Cholangiocarcinoma
  3. Focal nodular hyperplasia
  4. Hepatic hemangioma

Explanation

In a cirrhotic liver, arterial hyperenhancement followed by washout, with capsule appearance or threshold growth, satisfies major imaging criteria for definite hepatocellular carcinoma without biopsy. The combination is specific enough that LI-RADS assigns category 5.

Question 41Gastrointestinal imaging

A 70-year-old man has painless jaundice. CT shows a hypoattenuating mass in the pancreatic head with dilatation of both the common bile duct and the main pancreatic duct to the level of the mass. This appearance is termed the:

  1. Corkscrew sign
  2. Triple bubble sign
  3. Bird's beak sign
  4. Double duct sign Correct answer.

Explanation

Simultaneous dilatation of the common bile duct and main pancreatic duct at the level of a pancreatic head mass is the double duct sign, and it strongly suggests pancreatic head adenocarcinoma obstructing both ducts at the ampulla. It is not entirely specific and may occur with other periampullary tumors.

Question 42Gastrointestinal imaging

A patient with acute pancreatitis undergoes contrast-enhanced CT 12 hours after symptom onset, and the scan underestimates the extent of gland necrosis. What is the best explanation?

  1. Necrosis takes 48-72 hours to demarcate Correct answer.
  2. Necrosis is hypervascular in its earliest stage
  3. Intravenous contrast worsens necrosis immediately
  4. Necrosis never occurs before 1 week

Explanation

Pancreatic necrosis requires 48-72 hours or longer to become clearly demarcated as nonenhancing parenchyma, so very early CT can substantially underestimate it. For this reason, staging CT for necrosis is generally deferred about 72 hours or more after presentation unless the patient deteriorates.

Question 43Gastrointestinal imaging

Which imaging feature most favors Crohn disease over ulcerative colitis?

  1. Transmural skip lesions with fistula Correct answer.
  2. Lead-pipe colon
  3. Continuous mucosal disease from the rectum
  4. Pseudopolyps

Explanation

Crohn disease is transmural and discontinuous, producing skip lesions, creeping fat, deep ulceration, and fistulas or sinus tracts, whereas ulcerative colitis is a continuous mucosal disease beginning at the rectum. These transmural features are the key discriminator on CT or MR enterography.

Question 44Gastrointestinal imaging

CT in a 55-year-old with left lower quadrant pain shows a thick-walled sigmoid colon with a 2 cm extraluminal fluid collection containing gas and surrounding fat stranding. What is the most accurate description of this finding?

  1. Perforated appendicitis
  2. Epiploic appendagitis
  3. Ischemic colitis
  4. Diverticular abscess Correct answer.

Explanation

A gas- and fluid-containing collection adjacent to a thickened sigmoid colon in a patient with diverticulosis represents an abscess complicating diverticulitis (modified Hinchey stage Ib/II), which may be managed with percutaneous drainage. The presence of gas within the collection indicates contained perforation.

Question 45Gastrointestinal imaging

A 50-year-old woman has suspected choledocholithiasis with an equivocal right upper quadrant ultrasound and no signs of ascending cholangitis. Which noninvasive test is most appropriate next for detecting a common bile duct stone?

  1. Endoscopic retrograde cholangiopancreatography
  2. Abdominal radiograph
  3. Magnetic resonance cholangiopancreatography Correct answer.
  4. Hepatobiliary iminodiacetic acid scan

Explanation

MRCP is the preferred noninvasive study for choledocholithiasis, with high sensitivity and specificity and no ionizing radiation or contrast risk. ERCP is reserved for therapeutic intervention when a stone is documented or the patient has cholangitis or persistent obstruction.

Question 46Gastrointestinal imaging

CT shows a fluid-filled, dilated small bowel loop in a U shape with radially converging mesenteric vessels and a beak-like tapering at the site of obstruction. What does this pattern indicate?

  1. Acute colonic pseudo-obstruction
  2. Simple small bowel obstruction
  3. Adynamic ileus
  4. Closed-loop obstruction Correct answer.

Explanation

A U- or C-shaped distended loop with converging vessels and a beak at the point of torsion indicates a closed-loop obstruction, in which a segment is occluded at two points. This is a surgical emergency because of the high risk of strangulation and bowel infarction.

Question 47Gastrointestinal imaging

After blunt abdominal trauma, CT shows a grade III splenic laceration with a focal blush of contrast that enlarges on delayed phase imaging. What does this finding represent and what does it imply?

  1. Contained pseudoaneurysm needing no follow-up
  2. Active extravasation requiring angiography Correct answer.
  3. Beam-hardening artifact from prior contrast
  4. Splenic infarct from vascular injury

Explanation

A focus of contrast that follows blood pool on delayed imaging and enlarges represents active hemorrhage, which predicts failure of nonoperative management. These patients are typically referred for angiographic embolization.

Question 48Gastrointestinal imaging

An emaciated 80-year-old woman has a small bowel obstruction. CT shows a loop of bowel passing between the pectineus and obturator externus muscles. Which hernia is present?

  1. Inguinal hernia
  2. Sciatic hernia
  3. Obturator hernia Correct answer.
  4. Femoral hernia

Explanation

An obturator hernia passes through the obturator canal, coursing between the pectineus and obturator externus muscles, and classically affects thin, elderly multiparous women with obstruction. It may produce the Howship-Romberg sign from obturator nerve compression.

Question 49Gastrointestinal imaging

A hypotensive patient with lactic acidosis has CT showing pneumatosis of the right colon with gas in the superior mesenteric venous branches. How should this be interpreted?

  1. Pneumatosis cystoides intestinalis
  2. Resolving small bowel obstruction
  3. Ischemia requiring urgent surgery Correct answer.
  4. Benign finding; discharge home

Explanation

Pneumatosis intestinalis combined with portomesenteric venous gas in a patient with sepsis and lactic acidosis indicates transmural bowel ischemia and impending or actual infarction. This combination is a surgical emergency, and the portomesenteric gas portends high mortality.

Question 50Gastrointestinal imaging

A 60-year-old has a 9 cm well-circumscribed, exophytic, heterogeneously enhancing mass arising from the gastric wall, with central necrosis but no perigastric lymphadenopathy or obstruction. What is the most likely diagnosis?

  1. Gastric lymphoma
  2. Gastric adenocarcinoma
  3. GIST Correct answer.
  4. Gastric varix

Explanation

A large, well-marginated exophytic submucosal mass with heterogeneous enhancement and central necrosis but without nodal spread is characteristic of a gastrointestinal stromal tumor. GISTs arise from the interstitial cells of Cajal and spread hematogenously to the liver rather than via lymphatics.