GUT RADIOLOGY — EXAMINATION PAPER

SECTION A — UPPER GASTROINTESTINAL TRACT (Questions 1–10)

• A) Achalasia
• B) Squamous cell carcinoma of the esophagus ✓
• C) Peptic stricture
• D) Esophageal web
• E) External compression by lymph nodes

Explanation: An irregular shouldered filling defect with mucosal destruction on barium swallow is the classic appearance of esophageal carcinoma. Achalasia shows smooth tapering ("bird-beak" deformity). Peptic strictures are smooth and symmetric. (Grainger & Allison's Diagnostic Radiology)

• A) MRCP
• B) Endoscopic retrograde cholangiopancreatography (ERCP)
• C) CT abdomen with IV contrast
• D) Transabdominal ultrasound ✓
• E) FDG PET/CT

Explanation: Transabdominal ultrasound is inexpensive, widely available, and highly accurate in differentiating obstructive from non-obstructive causes of jaundice by assessing biliary ductal width. It is the recommended first-line investigation. (Grainger & Allison's Diagnostic Radiology)

• A) Esophageal carcinoma
• B) Esophageal spasm
• C) Achalasia ✓
• D) Scleroderma
• E) Hiatus hernia

Explanation: Achalasia produces failure of LES relaxation, resulting in the classic "bird-beak" tapering at the cardia with proximal megaesophagus. Scleroderma causes a patulous LES with reflux rather than tapering.

• A) Aberrant right subclavian artery (dysphagia lusoria) ✓
• B) Thoracic aortic aneurysm
• C) Enlarged lymph node
• D) Posterior mediastinal tumour
• E) Carcinoma of the esophagus

Explanation: An aberrant right subclavian artery (arteria lusoria) passes posterior to the esophagus and produces a characteristic oblique posterior impression on barium swallow, the cause of dysphagia lusoria.

• A) Benign gastric ulcer
• B) Gastric polyp
• C) Intraluminal gastric tumor with central ulceration ✓
• D) Gastric bezoar
• E) Ectopic pancreatic tissue

Explanation: The "meniscus sign" (Carman meniscus sign) is seen in malignant gastric ulcers — the ulcer is contained within a neoplastic mass and does not project beyond the gastric wall contour, unlike a benign ulcer.

• A) Ulcer confined within the gastric wall contour
• B) Heaped-up mucosal folds around the ulcer base
• C) Ulcer crater projecting beyond the gastric lumen on profile view ✓
• D) Meniscus (Carman) sign
• E) Rigidity of the adjacent gastric wall

Explanation: A benign gastric ulcer projects beyond the expected wall contour in profile view, with smooth radiating folds reaching the crater edge. Malignant ulcers are contained within the lumen, showing the meniscus sign and irregular folds.

• A) Single large gastric ulcer
• B) Multiple peptic ulcers extending into the jejunum with thickened folds ✓
• C) Linitis plastica appearance
• D) Bezoar formation
• E) Pyloric stenosis

Explanation: Zollinger-Ellison syndrome (gastrinoma) causes hypergastrinemia leading to multiple ulcers, including unusual sites such as the distal duodenum and proximal jejunum, with thickened mucosal folds and hypersecretion on barium studies.

• A) Esophageal carcinoma
• B) Killian-Jamieson diverticulum
• C) Plummer-Vinson (Paterson-Kelly) syndrome ✓
• D) Zenker diverticulum
• E) Cricopharyngeal spasm

Explanation: Plummer-Vinson (Paterson-Kelly) syndrome is associated with iron deficiency anemia and manifests as a smooth, thin, anterior esophageal web in the upper esophagus, predominantly in middle-aged women.

• A) A discrete polypoid mass
• B) Diffuse thickening of the gastric wall with loss of normal distensibility ✓
• C) A fluid-filled lesion within the gastric wall
• D) Calcification within the gastric wall
• E) Aneurysmal dilatation of the gastric fundus

Explanation: Linitis plastica (scirrhous carcinoma) results in diffuse infiltration and fibrosis of the gastric wall, producing a "leather bottle" stomach on barium studies and circumferential wall thickening with restricted distensibility on CT.

• A) It is seen in patients with hypoparathyroidism causing diffuse colonic calcifications
• B) It refers to alternating dense and lucent bands on a plain abdominal X-ray from bowel gas
• C) The term describes alternating dense end-plates of vertebrae seen in renal osteodystrophy — it is NOT a primary GI finding ✓
• D) It is pathognomonic for Crohn disease
• E) It is caused by thumbprinting in ischemic colitis

Explanation: The "rugger-jersey spine" is a skeletal radiological sign of renal osteodystrophy (not a GI finding), included here as a discriminatory question to test knowledge boundaries. Thumbprinting is the classic plain AXR sign in ischemic colitis/colitis.

SECTION B — SMALL BOWEL (Questions 11–20)

• A) Ulcerative colitis
• B) Lymphoma
• C) Crohn disease ✓
• D) Celiac disease
• E) Yersinia ileitis

Explanation: Crohn disease classically shows skip lesions, asymmetric transmural inflammation, longitudinal and transverse ulcers creating the "cobblestone" pattern, and terminal ileum involvement on SBFT. Ulcerative colitis is continuous from the rectum and confined to the colon.

• A) Pneumatosis intestinalis
• B) Mural stratification with mucosal hyperenhancement and the "comb sign" ✓
• C) Free intraperitoneal air
• D) Smooth concentric mural thickening without enhancement
• E) Mass effect displacing adjacent bowel loops

Explanation: Active Crohn disease on CTE shows mural hyperenhancement, mural stratification (the "target sign"), and increased vascularity of the adjacent mesenteric vessels creating the "comb sign." CT enterography has largely replaced barium SBFT for small bowel Crohn assessment. (Goldman-Cecil Medicine)

• A) Large bowel obstruction
• B) Paralytic ileus
• C) Mechanical small bowel obstruction ✓
• D) Toxic megacolon
• E) Volvulus of the sigmoid

Explanation: Small bowel obstruction on AXR shows centrally-located dilated loops (>3 cm), valvulae conniventes (complete across lumen), absence of colonic gas, and a "ladder" pattern. Large bowel obstruction produces peripheral loops with haustral markings. Paralytic ileus shows gas throughout both small and large bowel.

• A) Oral contrast not reaching the point of obstruction within 60 minutes
• B) Mesenteric fat stranding alone
• C) Pneumatosis intestinalis, portal venous gas, and lack of mural enhancement ✓
• D) Fluid levels on coronal reformats
• E) A single transition point

Explanation: Pneumatosis intestinalis (gas within the bowel wall), portal venous gas, and absent mural enhancement on contrast CT are radiological signs of bowel ischemia/infarction, signaling the need for emergency surgery. (Sleisenger and Fordtran's)

• A) Plain abdominal X-ray
• B) Upper GI endoscopy
• C) Technetium-99m-labeled RBC scintigraphy ✓
• D) CT angiography
• E) MR enterography

Explanation: Tc-99m RBC scintigraphy can detect bleeding rates as low as 0.1 mL/min, making it more sensitive than CT angiography (requires ~0.5 mL/min) or angiography (~1 mL/min) for intermittent or slow bleeding.

• A) Skip lesions in the ileum
• B) Folds in the jejunum are decreased ("jejunization of the ileum"), with increased folds in the ileum ✓
• C) Cobblestone mucosal pattern
• D) Stenotic segments in the proximal jejunum
• E) Thickened folds throughout the small bowel

Explanation: In celiac disease, loss of jejunal mucosal folds (due to villous atrophy) leads to relative "jejunization of the ileum" — ileal folds become more prominent while jejunal folds diminish. This pattern reversal is characteristic on barium studies.

• A) Gastrointestinal stromal tumour (GIST)
• B) Lymphoma
• C) Carcinoid tumour (well-differentiated neuroendocrine tumour) ✓
• D) Crohn disease
• E) Adenocarcinoma of small bowel

Explanation: Small bowel carcinoid most commonly arises in the terminal ileum, is often small, enhances avidly, and produces a characteristic desmoplastic mesenteric reaction with calcified lymph nodes and a "sunburst" pattern on CT. Flushing and diarrhea suggest carcinoid syndrome from hepatic metastases.

• A) Simple mechanical obstruction
• B) Mesenteric ischemia with submucosal hemorrhage/edema ✓
• C) Crohn disease
• D) Carcinoid
• E) Lymphoma

Explanation: "Thumbprinting" (smooth, rounded indentations on the bowel wall resembling thumbprints) on AXR represents submucosal edema or hemorrhage, classically seen in mesenteric ischemia, hemorrhage into the bowel wall, or ischemic colitis.

• A) It uses Tc-99m sulfur colloid
• B) It detects any Meckel diverticulum regardless of ectopic mucosa
• C) It relies on uptake of Tc-99m pertechnetate by ectopic gastric mucosa ✓
• D) Sensitivity exceeds 98% in adults
• E) It is the preferred modality in patients over 50 years

Explanation: The Meckel scan uses Tc-99m pertechnetate, which is taken up by gastric mucosa (parietal cells). It is only positive when ectopic gastric mucosa is present (about 50% of Meckel diverticula). Sensitivity is ~85% in children but lower in adults.

• A) Crohn colitis
• B) Ischemic colitis
• C) Ulcerative colitis ✓
• D) Pseudomembranous colitis
• E) Diverticular disease

Explanation: Chronic ulcerative colitis causes progressive loss of haustration, mucosal granularity, shortening, and narrowing of the colon, producing the featureless "lead pipe" or "hose pipe" appearance on barium enema.

SECTION C — LARGE BOWEL & APPENDIX (Questions 21–30)

• A) > 3 mm
• B) > 5 mm
• C) > 1 cm ✓
• D) > 1.5 cm
• E) > 2 cm

Explanation: CT colonography has sensitivity exceeding 90% for polyps ≥1 cm, 78–86% for polyps 5–9 mm, and consistently low sensitivity for diminutive polyps (<5 mm). These figures are from multiple comparative studies vs. optical colonoscopy. (Yamada's Textbook of Gastroenterology)

• A) Lower sensitivity for large polyps
• B) Requires general anaesthesia
• C) Inability to perform mucosal biopsy or polypectomy, requiring subsequent colonoscopy for positive findings ✓
• D) Higher radiation dose than barium enema
• E) Cannot assess extracolonic structures

Explanation: The key limitation of CT colonography is that polyps detected cannot be removed during the procedure — a subsequent optical colonoscopy is needed, adding cost and procedure burden. It also has low sensitivity for flat lesions. (Yamada's Gastroenterology)

• A) A smooth, well-defined pedunculated polyp
• B) A haustral fold thickened by submucosal edema
• C) An annular, constricting carcinoma causing luminal narrowing with shouldered margins ✓
• D) Diverticular phlegmon
• E) Extrinsic compression from a pelvic mass

Explanation: The "apple-core" lesion on barium enema or CT is the classic appearance of an annular colorectal carcinoma — irregular, circumferential narrowing with shouldered (overhanging) edges, resembling a bitten apple core.

• A) Free fluid in the right iliac fossa
• B) Periappendiceal fat stranding alone
• C) Appendicolith with a dilated, non-filling appendix ≥6 mm and periappendiceal stranding ✓
• D) Ileal thickening
• E) Reactive right-sided lymph nodes

Explanation: The combination of an appendicolith, an appendix diameter ≥6 mm with non-filling of the lumen, wall thickening, and periappendiceal fat stranding on CT has high PPV for acute appendicitis. CT with IV contrast is the most accurate single investigation. (Rosen's Emergency Medicine; Sabiston Surgery)

• A) Obese adult males
• B) Elderly patients
• C) Children and pregnant women ✓
• D) Immunocompromised patients
• E) Patients with previous appendectomy scar

Explanation: Ultrasound avoids ionizing radiation and is the preferred first-line modality in children and pregnant women. A non-compressible appendix >6 mm in diameter is the US criterion for appendicitis. If US is negative or inconclusive, CT or MRI (in pregnancy) is the next step. (Rosen's Emergency Medicine)

• A) Barium enema to assess extent of disease
• B) CT colonography
• C) Urgent surgical consultation and avoidance of colonoscopy/contrast enema ✓
• D) Oral laxatives and repeat AXR in 24 hours
• E) MR enterography

Explanation: Toxic megacolon (transverse colon diameter >6 cm with systemic toxicity) is a surgical emergency. Barium enema and colonoscopy are contraindicated due to perforation risk. CT of the abdomen is acceptable for assessment, but urgent surgical input is paramount.

• A) Central, ladder-pattern dilated loops
• B) A grossly distended loop of colon pointing to the right iliac fossa
• C) A large coffee-bean shaped gas-filled loop pointing to the right upper quadrant — the "northern exposure sign" of sigmoid volvulus ✓
• D) Pneumoperitoneum
• E) Thumbprinting of the transverse colon

Explanation: Sigmoid volvulus on AXR classically produces a large, inverted U-shaped (coffee-bean or omega loop) gas-filled loop rising from the pelvis toward the right upper quadrant (the "northern exposure" sign), with loss of haustration in the affected segment.

• A) Carcinoma of the rectum
• B) Diverticular stricture
• C) Sigmoid volvulus ✓
• D) Ogilvie syndrome
• E) Intussusception

Explanation: Sigmoid volvulus on contrast enema shows a smooth, tapered "bird-beak" obstruction at the site of the twist. This confirms the diagnosis and the water-soluble enema may also be therapeutic (decompression) in some cases.

• A) Location (central vs. peripheral) and mucosal fold pattern (valvulae conniventes crossing full lumen vs. haustral folds that do not cross fully) ✓
• B) Diameter alone
• C) Presence of air-fluid levels
• D) Presence of gas in the rectum
• E) The number of loops visible

Explanation: The key distinguishing features are: (1) Small bowel — central location, valvulae conniventes (complete folds across the lumen); (2) Large bowel — peripheral location, haustral markings (incomplete folds). Size thresholds alone are insufficient.

• A) CT colonography
• B) Transabdominal ultrasound
• C) Barium enema
• D) MRI pelvis ✓
• E) Endorectal ultrasound

Explanation: High-resolution MRI pelvis is the gold standard for local staging of rectal carcinoma, accurately defining the relationship of tumor to the mesorectal fascia (circumferential resection margin), which predicts likelihood of complete surgical excision and guides neoadjuvant therapy decisions.

SECTION D — LIVER, BILIARY TRACT & PANCREAS (Questions 31–40)

• A) Progressive fill-in from periphery to center (like a cavernous hemangioma)
• B) Arterial phase hyperenhancement with portal venous phase washout ✓
• C) Persistent low attenuation in all phases
• D) Central scar with delayed enhancement
• E) Calcification within the lesion

Explanation: HCC demonstrates the classic pattern of arterial hyperenhancement (due to arterial supply) followed by "washout" (becoming hypodense relative to liver) in the portal venous/delayed phase — the LI-RADS 5 hallmark criteria. (Yamada's Gastroenterology; Goldman-Cecil)

• A) Probably benign lesion requiring 6-month follow-up
• B) Definitely benign lesion — no follow-up required
• C) Intermediate probability of malignancy
• D) Definitely HCC ✓
• E) Definitely non-HCC malignancy

Explanation: LI-RADS (Liver Imaging Reporting and Data System) 5 denotes "definitely HCC" — requires arterial phase hyperenhancement plus one additional major feature (washout, enhancing capsule, or threshold growth). (Yamada's Textbook of Gastroenterology)

• A) Transabdominal ultrasound
• B) ERCP
• C) CT with IV contrast
• D) MRCP (Magnetic Resonance Cholangiopancreatography) ✓
• E) Hepatobiliary scintigraphy (HIDA scan)

Explanation: MRCP provides non-invasive, high-resolution imaging of the biliary and pancreatic ducts without radiation or contrast injection into the duct. It has largely replaced diagnostic ERCP for mapping biliary anatomy preoperatively.

• A) Dilated common bile duct (>6 mm)
• B) Shadowing echogenic focus within the common bile duct ✓
• C) Gallbladder wall thickening
• D) Pericholecystic fluid
• E) Murphy's sign elicited by the probe

Explanation: Visualization of a shadowing echogenic focus (stone) within the CBD lumen is highly specific for choledocholithiasis. Duct dilatation alone is sensitive but non-specific (also seen post-cholecystectomy, with age-related changes, etc.).

• A) Autoimmune pancreatitis
• B) Pancreatic pseudocyst
• C) IPMN (main duct type)
• D) Pancreatic ductal adenocarcinoma ✓
• E) Ampullary carcinoma

Explanation: The combination of Courvoisier's sign, hypodense pancreatic head mass, double-duct sign (simultaneous dilatation of CBD and main pancreatic duct), and upstream MPD dilatation is classic for pancreatic head adenocarcinoma. (Grainger & Allison's; Yamada's)

• A) Upstream pancreatic duct dilatation
• B) Vascular encasement
• C) Diffuse sausage-shaped pancreatic swelling with a peripheral halo/capsule-like rim ✓
• D) Hypodense lesion in the pancreatic head
• E) Double-duct sign

Explanation: AIP classically shows diffuse "sausage-shaped" enlargement of the pancreas with a characteristic peripheral low-attenuation halo/capsule on CT, reflecting fibroinflammatory tissue. It lacks upstream duct dilatation (which is absent or shows stricture without dilation) — crucial to distinguish from carcinoma to avoid unnecessary surgery. (Grainger & Allison's Diagnostic Radiology)

• A) Transabdominal ultrasound
• B) ERCP
• C) Contrast-enhanced multidetector CT (MDCT) in pancreatic parenchymal and venous phases ✓
• D) FDG PET/CT
• E) MRI with MRCP

Explanation: Contrast-enhanced hydrido-MDCT (water as oral contrast) in dual-phase (pancreatic parenchymal + portal venous) is the most widely used technique for diagnosis and staging of pancreatic cancer, reliably assessing vascular involvement and resectability. (Grainger & Allison's)

• A) A hypoechoic lesion with posterior acoustic enhancement
• B) A hyperechoic, well-defined lesion with posterior acoustic enhancement ✓
• C) A lesion with a central scar
• D) A heterogeneous lesion with thick internal septae
• E) An isoechoic lesion indistinguishable from normal parenchyma

Explanation: Cavernous hemangiomas are the most common benign hepatic tumors. They are typically well-defined, homogeneous, hyperechoic lesions on US with posterior acoustic enhancement. On contrast CT, they show characteristic peripheral nodular enhancement with progressive centripetal fill-in on delayed phases.

• A) Ultrasound with Doppler only
• B) Plain X-ray of the abdomen
• C) Multiphasic contrast-enhanced CT or MRI using LI-RADS criteria ✓
• D) HIDA scan
• E) Biopsy without prior imaging

Explanation: In cirrhotic patients, any liver nodule >1 cm should be assessed with multiphasic CT or MRI using LI-RADS criteria to characterize for HCC. Biopsy is not required if LI-RADS 5 criteria are met, as imaging diagnosis is accepted for treatment planning per EASL/AASLD guidelines.

• A) Branch-duct cyst <2 cm without mural nodule
• B) Main pancreatic duct dilatation 5–9 mm with mural nodule and obstructive jaundice ✓
• C) Incidental finding in an asymptomatic patient with MPD 3 mm
• D) Thin septae within the cyst
• E) Cyst wall calcification alone

Explanation: Main-duct IPMN with MPD ≥10 mm, presence of an enhancing mural nodule (especially >5 mm on CT/MRI), and obstructive jaundice are "high-risk stigmata" per international consensus guidelines (Fukuoka/European) for which surgical resection is recommended due to high risk of invasive carcinoma. (Grainger & Allison's; Clinical Gastrointestinal Endoscopy)

ANSWER KEY

TOPIC COVERAGE SUMMARY

• Grainger & Allison's Diagnostic Radiology (Elsevier)
• Yamada's Textbook of Gastroenterology, 7th Ed.
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease
• Goldman-Cecil Medicine
• Rosen's Emergency Medicine
• Sabiston Textbook of Surgery