Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology Indian Medical PG Practice Questions and MCQs

Question 361: Which is the most important sign of significance of renal artery stenosis on an angiogram?

A. Presence of collaterals (Correct Answer)
B. A percentage diameter stenosis > 70%
C. Post-stenotic dilatation of the renal artery
D. A systolic pressure gradient > 20 mm Hg across the lesion

Explanation: **Explanation:** The significance of renal artery stenosis (RAS) is determined by its functional impact on renal perfusion rather than just the anatomical degree of narrowing. **1. Why "Presence of Collaterals" is correct:** The development of collateral circulation is the most definitive angiographic evidence of a **hemodynamically significant** stenosis. Collaterals (typically from the adrenal, capsular, or ureteric arteries) only form when there is a persistent, significant pressure drop across the primary vessel. Their presence indicates that the stenosis is severe enough to have triggered compensatory mechanisms to maintain renal blood flow, making it the most reliable "sign of significance" on a static angiogram. **2. Why other options are incorrect:** * **Percentage diameter stenosis > 70%:** While a 70% narrowing is often used as a threshold for intervention, anatomical measurement alone can be misleading due to vessel overlap, eccentric plaques, or vasospasm. It does not guarantee functional impairment. * **Post-stenotic dilatation:** This is a common finding due to the "Jet effect" and turbulence distal to a narrowing, but it can occur even with non-significant stenosis and does not correlate directly with the severity of ischemia. * **Systolic pressure gradient > 20 mm Hg:** While this is a physiological marker of significance, it is a **hemodynamic measurement**, not an "angiographic sign" visible on a standard film without pressure wire manometry. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA) remains the gold standard for diagnosing RAS. * **Screening Tool:** Doppler Ultrasound (look for "Tardus Parvus" pulse) or CT Angiography. * **Common Causes:** Atherosclerosis (most common, involves the ostium/proximal 1/3) and Fibromuscular Dysplasia (classic "string of beads" appearance, involves the distal 2/3). * **Goldblatt Kidney:** The physiological model explaining renovascular hypertension due to RAS.

Question 362: In a CT scan at the level of the celiac trunk, which of the following structures will be seen?

A. Pancreas, Inferior vena cava, Portal vein (Correct Answer)
B. Gall bladder, Duodenum, Portal vein
C. Inferior vena cava, Duodenum, Portal vein
D. Pancreas, Duodenum, Portal vein

Explanation: ### Explanation The **celiac trunk** originates from the ventral surface of the abdominal aorta at the level of the **T12-L1 vertebrae**. Understanding the cross-sectional anatomy at this level is crucial for identifying key abdominal structures. **1. Why Option A is Correct:** * **Pancreas:** The body and tail of the pancreas lie at the T12-L1 level, situated anterior to the celiac axis and the splenic vein. * **Inferior Vena Cava (IVC):** The IVC ascends to the right of the aorta and is consistently visible in upper abdominal cross-sections. * **Portal Vein:** The formation of the portal vein (union of the superior mesenteric and splenic veins) occurs posterior to the neck of the pancreas at the L1 level, making it visible at the celiac trunk's origin. **2. Why Other Options are Incorrect:** * **Duodenum (Options B, C, D):** The majority of the duodenum (specifically the 2nd, 3rd, and 4th parts) lies lower, between **L2 and L3**. While the 1st part starts at L1, it is usually seen slightly inferior to the celiac trunk's takeoff. * **Gallbladder (Option B):** The gallbladder is typically located at the **L2-L3 level**, tucked under the inferior border of the liver. It is not seen at the high T12-L1 level of the celiac trunk. **3. Clinical Pearls for NEET-PG:** * **"Seagull Sign":** On a CT scan, the celiac trunk and its branches (splenic and common hepatic arteries) form a shape resembling a seagull. * **Vertebral Levels:** * **Celiac Trunk:** T12-L1 * **SMA:** L1 (just below the celiac) * **Renal Arteries:** L2 * **IMA:** L3 * **Transpyloric Plane (L1):** This is a high-yield landmark where the hila of the kidneys, the neck of the pancreas, and the origin of the portal vein are located.

Question 363: Which condition is characterized by a "saw tooth" appearance?

A. Diverticulosis (Correct Answer)
B. Cholecystitis
C. Appendicitis
D. Hiatus hernia

Explanation: **Explanation:** The **"saw tooth" appearance** is a classic radiological sign seen on a barium enema in patients with **Diverticulosis**, specifically during the stage of muscular hypertrophy (prediverticular phase). 1. **Why Diverticulosis is correct:** The appearance is caused by two factors: the thickening and shortening of the *taeniae coli* (longitudinal muscle bands) and the circular muscle hypertrophy. This creates a series of sharp, serrated indentations along the colonic wall, resembling the teeth of a saw. This is most commonly observed in the sigmoid colon. 2. **Why other options are incorrect:** * **Cholecystitis:** Typically diagnosed via ultrasound (thickened gallbladder wall, pericholecystic fluid). A specific radiological sign is the "Rim sign" on HIDA scan or "Champagne sign" (emphysematous cholecystitis). * **Appendicitis:** Characterized by a dilated appendix (>6mm) and an "appendicolith" on CT. It does not produce a saw-tooth pattern. * **Hiatus hernia:** Identified by the presence of the stomach above the diaphragm on a barium swallow, often showing a "Schatzki ring" or "retrocardiac air-fluid level" on X-ray. **High-Yield Clinical Pearls for NEET-PG:** * **Diverticulosis:** Most common site is the **Sigmoid Colon**. It is a "false diverticulum" (only mucosa and submucosa herniate). * **Imaging of Choice:** **CT scan** is the gold standard for *acute diverticulitis* (to avoid perforation risk with barium). Barium enema is used for chronic diverticulosis. * **Other "Tooth" Signs:** Do not confuse this with the "Molar tooth sign" seen in **Joubert Syndrome** (Midbrain-hindbrain malformation).

Question 364: Which of the following are CT findings of acute pancreatitis?

A. Fuzzy outline of pancreas
B. Dilatation of pancreatic duct system
C. Peripancreatic fluid collection
D. All of the above (Correct Answer)

Explanation: Acute pancreatitis is an inflammatory condition where Contrast-Enhanced Computed Tomography (CECT) is the gold standard for diagnosis and staging (ideally performed 72–96 hours after symptom onset). **Explanation of Findings:** * **Fuzzy outline of pancreas:** In the early stages, inflammation causes interstitial edema, leading to a loss of the sharp, lobulated borders of the pancreas. This is often described as "shaggy" or "fuzzy" contours. * **Dilatation of pancreatic duct system:** While more common in chronic pancreatitis, acute inflammation or an obstructing gallstone (the most common cause) can lead to transient dilatation of the Main Pancreatic Duct (MPD). * **Peripancreatic fluid collection:** Inflammatory exudates leak into the retroperitoneal spaces (specifically the anterior pararenal space), appearing as areas of low attenuation surrounding the gland. **Why "All of the above" is correct:** Acute pancreatitis is a spectrum. Early/mild cases show gland enlargement and **fuzzy outlines** (Option A). As the disease progresses, enzymatic leak leads to **fluid collections** (Option C). If the etiology is obstructive or if there is significant head edema, **ductal dilatation** (Option B) occurs. Therefore, all three are recognized CT features. **NEET-PG High-Yield Pearls:** 1. **Modified CT Severity Index (MCTSI):** Used to assess prognosis based on pancreatic inflammation, necrosis, and extrapancreatic complications. 2. **Balthazar Grading:** A classic CT grading system (A to E) based on the presence of inflammation and fluid collections. 3. **Timing:** CECT is not usually indicated in the first 24 hours unless the diagnosis is uncertain, as necrosis may not be visible yet. 4. **Sentinel Loop:** A classic X-ray finding (dilated proximal jejunal loop) seen in acute pancreatitis.

Question 365: The 'cobra snake head' appearance is typically seen in which condition?

A. Rectocele
B. Ureterocele (Correct Answer)
C. Posterior urethral valve
D. Bladder tumor

Explanation: **Explanation:** The **'Cobra head'** or **'Adder head'** appearance is a classic radiological sign of a **Ureterocele** (specifically the intravesical type). **1. Why Ureterocele is correct:** A ureterocele is a congenital cystic dilatation of the distal-most intramural portion of the ureter. On an Intravenous Pyelogram (IVP) or contrast CT, the dilated terminal ureter appears as a radiopaque bulbous area surrounded by a thin radiolucent halo (representing the ureteric wall and bladder mucosa). This combination mimics the head of a cobra. **2. Why the other options are incorrect:** * **Rectocele:** This is a herniation of the rectum into the posterior vaginal wall, typically diagnosed via defecography or clinical exam; it does not produce a cobra-head sign. * **Posterior Urethral Valve (PUV):** This is characterized by the **'Keyhole sign'** on ultrasound (dilated posterior urethra and thick-walled bladder) in male infants. * **Bladder Tumor:** While a tumor can cause a filling defect in the bladder, it is usually irregular and lacks the characteristic symmetrical lucent halo of a ureterocele. **3. High-Yield Clinical Pearls for NEET-PG:** * **Radiological Signs:** The 'Cobra head' sign is seen on **IVP/Excretory Urography**. On ultrasound, it appears as a "cyst within a cyst." * **Ectopic Ureterocele:** Often associated with a **duplicated collecting system** (Weigert-Meyer Law), where the ureter from the upper pole inserts ectopically and prone to ureterocele formation. * **Differential Diagnosis:** If the radiolucent halo is thick or irregular, consider a **'Pseudoureterocele'**, which can be caused by a bladder tumor or an impacted stone at the UVJ.

Question 366: Tuberous sclerosis is characterized by all EXCEPT:

A. Multiple renal cysts
B. Arachnoid cysts (Correct Answer)
C. Renal angiomyolipomas
D. Renal cell carcinoma

Explanation: **Explanation:** Tuberous Sclerosis Complex (TSC) is an autosomal dominant neurocutaneous syndrome (phakomatosis) caused by mutations in the **TSC1 (Hamartin)** or **TSC2 (Tuberin)** genes. It is characterized by the development of benign tumors (hamartomas) in multiple organs. **Why Arachnoid Cysts are the correct answer:** Arachnoid cysts are **not** a characteristic feature of Tuberous Sclerosis. The classic intracranial findings in TSC include **cortical tubers**, **subependymal nodules (SENs)**, and **Subependymal Giant Cell Astrocytomas (SEGAs)**. Arachnoid cysts are more commonly associated with other conditions or occur sporadically. **Analysis of Incorrect Options:** * **Renal Angiomyolipomas (AMLs):** These are the most common renal manifestation of TSC (seen in ~70-80% of patients). They are often bilateral, multiple, and carry a risk of hemorrhage (Wunderlich syndrome). * **Multiple Renal Cysts:** These occur in about 20% of TSC patients. Notably, the TSC2 gene is adjacent to the **PKD1** gene on chromosome 16; a contiguous gene syndrome can lead to severe, early-onset polycystic kidney disease. * **Renal Cell Carcinoma (RCC):** While less common than AMLs, patients with TSC have an increased risk of developing RCC, often at a younger age than the general population. **High-Yield Clinical Pearls for NEET-PG:** * **Vogt’s Triad:** Adenoma sebaceum (facial angiofibromas), mental retardation, and seizures (present in only ~30%). * **Dermatological markers:** Ash-leaf spots (earliest sign), Shagreen patches, and periungual fibromas (Koenen tumors). * **Cardiac:** Rhabdomyomas (often regress spontaneously). * **Pulmonary:** Lymphangioleiomyomatosis (LAM) – typically in females. * **Radiology "Hot Tip":** On CT, Subependymal Nodules often show calcification ("candle guttering" appearance).

Question 367: Spider leg appearance on intravenous pyelogram (IVP) is suggestive of which of the following?

A. Renal cyst (Correct Answer)
B. Renal carcinoma
C. Renal tuberculosis
D. Hydronephrosis

Explanation: **Explanation:** The **"Spider leg appearance"** on an Intravenous Pyelogram (IVP) is a classic radiological sign of a **Renal Cyst**. This appearance occurs when a large, simple cortical cyst exerts pressure on the renal collecting system. The cyst causes elongation, thinning, and stretching of the renal calyces without destroying them, making them resemble the long, thin legs of a spider. **Analysis of Options:** * **Renal Cyst (Correct):** As the cyst expands, it displaces the infundibula and calyces. Because the cyst is smooth and benign, it stretches the structures rather than invading them, leading to the characteristic "spider leg" deformity. * **Renal Carcinoma:** While it can also displace calyces, Renal Cell Carcinoma (RCC) is more likely to cause irregular destruction, amputation of calyces, or a "moth-eaten" appearance due to its invasive nature. * **Renal Tuberculosis:** Typically presents with "moth-eaten" calyces (early stage) or a "Putty kidney" (autonephrectomy) in late stages. It is characterized by strictures and cavitation rather than simple stretching. * **Hydronephrosis:** This results in the dilation and blunting of the calyces (clubbing), eventually leading to a "ballooned" appearance of the pelvis, which is the opposite of the thinning seen in the spider leg sign. **High-Yield Clinical Pearls for NEET-PG:** * **Spider leg appearance:** Renal Cyst (most common) or Polycystic Kidney Disease (PKD). * **Moth-eaten calyces:** Early Renal TB. * **Flower-vase appearance:** Horseshoe Kidney. * **Maiden-waist deformity:** Retrocaval Ureter. * **Drooping lily sign:** Duplex collecting system (obstructed upper pole). * **Rim sign:** Severe Hydronephrosis.

Question 368: Ultrasonography of the liver shows a starry sky appearance. This is a feature of which condition?

A. Acute viral hepatitis (Correct Answer)
B. Primary biliary cirrhosis
C. Primary sclerosing cholangitis
D. Hydatid cyst

Explanation: ### Explanation **Correct Answer: A. Acute viral hepatitis** The **"Starry Sky" appearance** on ultrasound is a classic radiological sign of **Acute Viral Hepatitis**. This pattern is created by two concurrent pathological processes: 1. **Decreased Liver Echogenicity:** Due to diffuse hepatocellular edema, the liver parenchyma becomes darker (hypoechoic). 2. **Increased Portal Triad Echogenicity:** The walls of the portal venous branches appear bright (hyperechoic) and more prominent against the dark background of the edematous liver. **Analysis of Incorrect Options:** * **B & C (Primary Biliary Cirrhosis & Primary Sclerosing Cholangitis):** These are chronic cholestatic diseases. They typically present with features of cirrhosis (nodular surface, coarse echotexture) or biliary tree abnormalities (beading of ducts in PSC), rather than the starry sky pattern. * **D (Hydatid Cyst):** This presents with characteristic cystic patterns, such as the **"Water Lily sign"** (detached endocyst) or a **"Wheel-spoke appearance"** (daughter cysts), rather than diffuse parenchymal changes. **High-Yield Clinical Pearls for NEET-PG:** * **Sensitivity:** While "Starry Sky" is a classic textbook sign, it is not highly sensitive; many patients with acute hepatitis have a normal-looking liver on USG. * **Differential Diagnosis:** A similar appearance can occasionally be seen in **Leukemic infiltration** of the liver, toxic shock syndrome, or fasting. * **Gallbladder involvement:** In acute hepatitis, look for **diffuse gallbladder wall thickening** with a small lumen (due to decreased bile production). * **Contrast:** The opposite of the starry sky is the **"Bright Liver,"** seen in **Fatty Liver (Steatosis)**, where the parenchyma is hyperechoic and portal vein walls are poorly visualized.

Question 369: Which of the following is NOT a diagnostic feature of gallstone ileus on a plain abdominal radiograph?

A. Ectopic calcified gallstone
B. Stone < 2.5 cm in size within the intestine (Correct Answer)
C. Signs of small intestinal obstruction
D. Gas within the biliary tree

Explanation: **Explanation:** **Gallstone ileus** is a mechanical small bowel obstruction caused by the impaction of a large gallstone that has migrated through a cholecysto-enteric fistula (most commonly into the duodenum). **Why Option B is the correct answer:** For a gallstone to cause a mechanical obstruction (ileus), it typically needs to be **at least 2.5 cm** in diameter. Smaller stones usually pass through the ileocecal valve without causing obstruction. Therefore, a stone smaller than 2.5 cm is not a classic diagnostic feature of this pathology; rather, the presence of a **large** ectopic stone is the hallmark. **Analysis of Incorrect Options (Rigler’s Triad):** The diagnosis of gallstone ileus on a plain radiograph is based on **Rigler’s Triad**, which includes: * **Option A (Ectopic gallstone):** A calcified stone seen outside the gallbladder fossa, often in the right iliac fossa (the ileum is the narrowest part of the small bowel). * **Option C (Small bowel obstruction):** Dilated small bowel loops with air-fluid levels due to the mechanical blockage. * **Option D (Pneumobilia):** Gas within the biliary tree occurs because the fistula allows air from the gut to enter the bile ducts. **NEET-PG High-Yield Pearls:** * **Rigler’s Triad:** Pneumobilia + Small bowel obstruction + Ectopic gallstone (seen in ~30-35% of cases on X-ray). * **Most common site of impaction:** Terminal ileum (narrowest part). * **Most common fistula:** Cholecystoduodenal fistula. * **Bouveret Syndrome:** A specific type of gallstone ileus where the stone impacts in the duodenum, causing gastric outlet obstruction. * **Investigation of Choice:** CT abdomen (highly sensitive for identifying the stone and the fistula).

Question 370: What is the most sensitive and specific investigation in renal artery hypertension?

A. Captopril-enhanced renal scan
B. Doppler ultrasound
C. MRI (Correct Answer)
D. CT scan

Explanation: **Explanation:** The diagnosis of Renovascular Hypertension (RVH) requires identifying both a significant renal artery stenosis (RAS) and the functional activation of the renin-angiotensin system. **Why MRI is the correct answer:** Magnetic Resonance Angiography (MRA), particularly **Gadolinium-enhanced MRA**, is currently considered the most sensitive and specific non-invasive investigation for renal artery stenosis. It provides high-resolution anatomical detail of the renal arteries and can detect stenotic lesions even in the presence of calcification, which often limits CT. Furthermore, MRI can assess functional parameters like renal perfusion and glomerular filtration rate (GFR) without the risk of ionizing radiation. **Analysis of Incorrect Options:** * **Captopril-enhanced renal scan:** While historically popular for assessing the functional significance of a known stenosis, it has lower sensitivity and specificity compared to MRA, especially in patients with bilateral disease or renal insufficiency. * **Doppler Ultrasound:** Though useful as a screening tool because it is inexpensive and non-invasive, it is highly operator-dependent and often limited by patient habitus or overlying bowel gas. * **CT Scan:** CT Angiography (CTA) is highly accurate but carries the risk of contrast-induced nephropathy (CIN) and involves significant radiation exposure. In many clinical guidelines, MRA is preferred over CTA when available due to its superior safety profile in patients with potentially compromised renal function. **NEET-PG High-Yield Pearls:** * **Gold Standard:** Digital Subtraction Angiography (DSA) remains the "Gold Standard" (invasive) for diagnosis and allows for simultaneous intervention (angioplasty). * **Most Common Cause:** Atherosclerosis (older males, proximal artery) followed by Fibromuscular Dysplasia (younger females, distal artery/string of beads appearance). * **Screening Choice:** Doppler is often the initial screening test, but MRA is the most definitive non-invasive diagnostic tool.

Practice by Chapter

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Renal and Urinary Tract Imaging

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Adrenal Imaging

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Male Pelvic Imaging

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Abdominal Trauma Imaging

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Acute Abdomen Imaging

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