Abdominal and Pelvic Radiology Practice Questions

Q: Radio-lucent renal stones are typically composed of which substance?

Uric acid. ### Explanation The radiopacity of a renal stone on a plain X-ray (KUB) depends on its effective atomic number. Stones containing elements with high atomic numbers, like Calcium, appear **radio-opaque** (white), while those composed of organic compounds without heavy metals appear **radiolucent** (black/invisible). **1. Why Uric Acid is Correct:** Uric acid stones are composed of carbon, nitrogen, oxygen, and hydrogen. These elements have low atomic numbers, making the stones **radiolucent** on conventional radiography. However, they are easily visualized as "hyperdense" on a Non-Contrast CT (NCCT) scan, which is the gold standard for diagnosis. **2. Analysis of Incorrect Options:** * **Calcium Phosphate (Option B):** These are the most radio-opaque stones due to the high atomic number of Calcium. * **Cysteine (Option A):** These stones contain sulfur atoms. While they are less opaque than calcium stones, they are described as **"ground-glass"** or **faintly radio-opaque**, not radiolucent. * **All of the above (Option D):** Incorrect, as the degree of opacity varies significantly between chemical compositions. **3. Clinical Pearls for NEET-PG:** * **Mnemonic for Radiolucent Stones (PU):** **P**urine (Uric acid) and **U**ndissolved medications (like Indinavir). * **Gold Standard Investigation:** NCCT KUB (detects all stones except Indinavir stones). * **Struvite Stones (Triple Phosphate):** Associated with Proteus infections; they are radio-opaque and often form **Staghorn calculi**. * **Management Tip:** Uric acid stones are unique because they can often be dissolved via **urinary alkalinization** (maintaining pH > 6.5).

Q: Which of the following is the most specific and sensitive screening test for renovascular hypertension?

CT angiography. **Explanation:** **Renovascular Hypertension (RVH)** is primarily caused by Renal Artery Stenosis (RAS), leading to activation of the Renin-Angiotensin-Aldosterone System (RAAS). **Why CT Angiography (CTA) is correct:** CTA is currently considered the **most sensitive (95-98%) and specific (90-94%)** non-invasive screening tool for detecting renal artery stenosis. It provides high-resolution anatomical detail, allowing for the visualization of the main renal arteries as well as accessory arteries. It is particularly superior in identifying stenosis caused by atherosclerosis or fibromuscular dysplasia (FMD). **Analysis of Incorrect Options:** * **A. HRCT:** High-Resolution CT is used primarily for lung parenchyma imaging (e.g., interstitial lung disease) and has no role in vascular imaging or renovascular hypertension. * **C. Captopril Radionuclide Scan:** While historically popular, its sensitivity is lower than CTA, especially in patients with impaired renal function or bilateral disease. It is a functional test rather than an anatomical one. * **D. MRI (MRA):** Magnetic Resonance Angiography is highly accurate but generally slightly less sensitive than CTA for distal or accessory renal arteries. It is also more expensive and contraindicated in patients with metallic implants or severe renal failure (due to Nephrogenic Systemic Fibrosis risk). **NEET-PG High-Yield Pearls:** * **Gold Standard (Definitive Test):** Digital Subtraction Angiography (DSA). It is both diagnostic and therapeutic (allows for stenting). * **Best Initial Screening (Non-invasive):** Duplex Doppler Ultrasound (though operator-dependent). * **Most Sensitive/Specific Screening:** CT Angiography. * **Commonest cause of RAS:** Atherosclerosis (older males) followed by Fibromuscular Dysplasia (young females; "string of beads" appearance).

Q: A patient with abdominal pain shows a "coffee bean" sign in a plain abdominal X-ray. What is the probable diagnosis?

Sigmoid volvulus. ### Explanation **1. Why Sigmoid Volvulus is Correct:** The **"Coffee Bean" sign** (also known as the Omega sign or Frimann-Dahl sign) is the pathognomonic radiographic feature of **Sigmoid Volvulus**. This condition occurs when the sigmoid colon twists on its mesenteric axis, leading to a closed-loop obstruction. The resulting massive dilation of the sigmoid loop creates a smooth, U-shaped shadow that resembles a giant coffee bean. The "bean" typically points toward the right upper quadrant, and its "cleft" is formed by the two adjacent inner walls of the twisted loop. **2. Analysis of Incorrect Options:** * **Colon Carcinoma:** Typically presents with an **"Apple Core" lesion** (annular constriction) on a barium enema, rather than a single massive dilated loop. * **Duodenal Atresia:** Characterized by the **"Double Bubble" sign** on X-ray, representing air in the stomach and the proximal duodenum, usually seen in neonates. * **Acute Pancreatitis:** Common radiographic findings include the **"Sentinel Loop"** (localized ileus of a jejunal loop) or the **"Colon Cut-off sign"** (abrupt collapse of the colon near the splenic flexure), but not a coffee bean appearance. **3. High-Yield Clinical Pearls for NEET-PG:** * **Bird’s Beak Sign:** Seen on a barium enema at the site of the twist in sigmoid volvulus. * **Whirl Sign:** The classic appearance of twisted mesentery on a CT scan. * **Management:** Initial treatment is often **sigmoidoscopic detorsion** (unless gangrene is suspected), followed by elective surgery to prevent recurrence. * **Cecal Volvulus:** Unlike sigmoid, the dilated loop in cecal volvulus usually has only one air-fluid level and tends to point toward the left upper quadrant.

Q: What does the cholangiogram show?

Klatskin Tumor. ***Klatskin Tumor*** - Cholangiogram shows **abrupt cut-off** or **stricture** at the **hepatic duct confluence** (Klatskin tumor location), with **bilateral intrahepatic ductal dilatation**. - Classic **"pruned tree" appearance** with dilated intrahepatic ducts proximal to the obstruction and absence of contrast beyond the hilar region. *Gall stones* - Gallstones appear as **filling defects** within the gallbladder on cholangiography, not as ductal strictures. - Would show **mobile radiolucent areas** within the gallbladder contrast, without upstream biliary dilatation. *Choledocholithiasis* - Shows **filling defects** within the **common bile duct** rather than hilar strictures. - Characterized by **ductal dilatation proximal** to the stone with **abrupt transition** at the stone location, not at the hepatic duct confluence. *Porcelain gall bladder* - Appears as **rim-like calcification** of the gallbladder wall on imaging, not visible on cholangiography. - Cholangiogram would show **non-filling** or **non-visualization** of the gallbladder due to chronic inflammation and calcification.

Q: The 'bowler hat' sign is radiographically observed in which of the following conditions?

Sessile colonic polyp. **Explanation:** The **'Bowler Hat' sign** is a classic radiological sign seen on a **double-contrast barium enema**. It represents a **sessile colonic polyp** or a pedunculated polyp viewed head-on. **Why it occurs:** When a polyp is coated with barium and surrounded by air, it projects into the lumen. Depending on the orientation of the polyp relative to the X-ray beam, the barium collects in the "moat" or the angle between the polyp and the colonic wall, creating a ring-like shadow. The "dome" of the hat represents the surface of the polyp, and the "brim" represents the barium at the base. * **Crucial distinction:** If the "hat" points **toward** the center of the lumen, it is a polyp. If it points **away** from the lumen, it represents a diverticulum. **Analysis of Incorrect Options:** * **Sigmoid Volvulus:** Characterized by the **'Coffee Bean' sign** or 'Omega' sign on X-ray, and the 'Bird’s Beak' sign on barium enema. * **Midgut Volvulus:** Classically shows the **'Whirlpool' sign** on Doppler USG/CT and a 'Corkscrew' appearance of the distal duodenum on contrast studies. * **Intussusception:** Associated with the **'Target' or 'Donut' sign** on USG and the **'Coiled Spring' appearance** on barium enema. **NEET-PG High-Yield Pearls:** * **Polyp 2cm:** High risk of malignancy. * **Mexican Hat Sign:** Another name for the bowler hat sign when seen head-on. * **Apple Core Deformity:** Classic sign for annular Constricting Carcinoma of the colon.

Q: What does the term "pseudo kidney" refer to in medical imaging?

A thickened bowel loop on ultrasonography. ### Explanation **1. Why Option A is Correct:** The **"Pseudo-kidney sign"** is a classic ultrasonographic finding where a segment of bowel mimics the appearance of a kidney. In a cross-sectional or longitudinal view, a **thickened bowel wall** (which is hypoechoic/dark) surrounds the **central mucosal/luminal contents** (which are hyperechoic/bright). This creates an appearance similar to the renal cortex surrounding the echogenic renal sinus. It is most commonly associated with: * **Intussusception** (Target or doughnut sign in transverse; pseudo-kidney in longitudinal). * **Gastrointestinal malignancies** (e.g., Adenocarcinoma of the colon or Lymphoma). * **Inflammatory Bowel Disease** (e.g., Crohn’s disease). **2. Why the Other Options are Incorrect:** * **Option B (Hydronephrosis):** This refers to the dilation of the renal pelvis and calyces due to obstruction. On USG, it appears as a branching, fluid-filled (anechoic) collecting system, not a bowel-like structure. * **Option C (Unascended kidney):** Also known as an **Ectopic Kidney** (e.g., Pelvic kidney). While the kidney is in an abnormal location, it is a true kidney, not a "pseudo" mimic. * **Option D (Undescended testes):** This refers to **Cryptorchidism**. On USG, an undescended testis appears as an oval, homogeneous, hypoechoic structure, usually located in the inguinal canal. **3. Clinical Pearls for NEET-PG:** * **Target/Doughnut Sign:** The transverse equivalent of the pseudo-kidney sign, highly characteristic of **Intussusception**. * **Hayfork Sign:** Another USG sign of intussusception seen in the longitudinal plane (representing the layers of the intussusceptum). * **High-Yield Tip:** If a "pseudo-kidney" is seen in an elderly patient with weight loss, think **Colonic Carcinoma**. If seen in a child with colicky pain, think **Intussusception**.

Q: Multiple air-fluid levels in a child are seen in which condition?

Ileal obstruction. **Explanation:** The presence of **multiple air-fluid levels** on an erect abdominal X-ray is a hallmark sign of **distal small bowel obstruction**, such as **Ileal obstruction**. 1. **Why Ileal obstruction is correct:** In distal obstructions, a large segment of the small intestine (jejunum and ileum) proximal to the blockage fills with swallowed air and secreted fluid. On an upright film, gravity causes the fluid to settle, creating multiple "stair-step" air-fluid levels. Generally, more than 2–3 air-fluid levels are considered pathological in children. 2. **Why other options are incorrect:** * **Gastric obstruction:** Typically presents with a single large air-fluid level in the left upper quadrant (the dilated stomach) and a "gasless abdomen" distally. * **Duodenal obstruction:** Classically presents with the **"Double Bubble Sign"** (air in the stomach and proximal duodenum). There are usually only two air-fluid levels; the rest of the distal bowel is gasless. * **Esophageal atresia:** If there is no tracheoesophageal fistula (TEF), the abdomen will be completely gasless. If a distal TEF is present, there may be gas, but it does not typically present with multiple air-fluid levels unless a secondary lower obstruction exists. **NEET-PG High-Yield Pearls:** * **Double Bubble Sign:** Duodenal Atresia, Annular Pancreas, Midgut Volvulus. * **Triple Bubble Sign:** Jejunal Atresia. * **Step-ladder pattern:** Classic description for multiple air-fluid levels in small bowel obstruction. * **Coiled Spring Sign:** Seen on contrast studies in Intussusception. * **String Sign of Kantor:** Seen in Crohn’s disease (terminal ileum).

Q: Which of the following liver metastases appear hypoechoic on ultrasound?

Carcinoma of the breast. ### Explanation Liver metastases are the most common malignant tumors of the liver. Their appearance on ultrasound depends on the vascularity, cellularity, and collagen content of the primary tumor. **1. Why Carcinoma of the Breast is correct:** Breast carcinoma metastases are typically **hypoechoic** because they are often highly cellular with minimal stroma or internal architecture. Hypoechoic lesions are the most common presentation for metastases from lymphomas and most solid organ primaries, including the breast and lung. **2. Analysis of Incorrect Options:** * **Carcinoma of the Colon (Option A):** These are characteristically **hyperechoic**. This is due to the high degree of vascularity or the presence of microcalcifications and fibrous tissue within the metastatic deposits. * **Carcinoma of the Bladder (Option C):** While variable, urothelial cell metastases often present with mixed echogenicity or hyperechoic patterns compared to the more consistently hypoechoic breast metastases. * **Mucinous Adenocarcinoma (Option D):** These typically appear **hyperechoic** or may show cystic components. The presence of mucin and associated calcifications increases the acoustic impedance, leading to a brighter (hyperechoic) appearance. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hyperechoic Metastases:** Think "GI and Vascular"—Colon (most common), Renal Cell Carcinoma, Carcinoid, and Choriocarcinoma. * **Hypoechoic Metastases:** Think "Solid and Lymphatic"—Breast, Lung, and Lymphoma. * **Target/Bull’s Eye Sign:** A hypoechoic halo around a liver lesion is highly suggestive of malignancy (metastasis). * **Calcified Metastases:** Most commonly associated with **Mucinous Adenocarcinoma of the Colon**. * **Cystic Metastases:** Often seen in Cystadenocarcinoma of the ovary or pancreas, and Sarcomas (due to central necrosis).

Question 1

Radio-lucent renal stones are typically composed of which substance?

Accepted Answer

Uric acid

Answer

Cysteine

Answer

Calcium phosphate

Answer

All of the above

Question 2

Which of the following is the most specific and sensitive screening test for renovascular hypertension?

Accepted Answer

CT angiography

Answer

HRCT

Answer

Captopril enhanced radionuclide scan

Answer

MRI

Question 3

A patient with abdominal pain shows a "coffee bean" sign in a plain abdominal X-ray. What is the probable diagnosis?

Accepted Answer

Sigmoid volvulus

Answer

Colon carcinoma

Answer

Duodenal atresia

Answer

Acute pancreatitis

Question 4

Non-visualization of the gastric fundic bubble with an air-fluid level in the retrocardiac region suggests which of the following?

Accepted Answer

Achalasia cardia

Answer

Carcinoma esophagus

Answer

Esophageal web

Answer

Congenital hypertrophic pyloric stenosis

Question 5

What does the cholangiogram show?

Accepted Answer

Klatskin Tumor

Answer

Gall stones

Answer

Choledocholithiasis

Answer

Porcelain gall bladder

Question 6

The 'bowler hat' sign is radiographically observed in which of the following conditions?

Accepted Answer

Sessile colonic polyp

Answer

Sigmoid volvulus

Answer

Midgut volvulus

Answer

Intussusception

Question 7

What does the term "pseudo kidney" refer to in medical imaging?

Accepted Answer

A thickened bowel loop on ultrasonography

Answer

Hydronephrosis

Answer

An unascended kidney

Answer

Undescended testes

Question 8

Multiple air-fluid levels in a child are seen in which condition?

Accepted Answer

Ileal obstruction

Answer

Gastric obstruction

Answer

Duodenal obstruction

Answer

Esophageal atresia

Question 9

Which of the following are true features of cholecystitis on ultrasonography?

Accepted Answer

Thick fibrosed gallbladder wall

Answer

Stone impacted at the neck of the gallbladder

Answer

Pericholecystic halo

Answer

Increased vascularity

Question 10

Which of the following liver metastases appear hypoechoic on ultrasound?

Accepted Answer

Carcinoma of the breast

Answer

Carcinoma of the colon

Answer

Carcinoma of the bladder

Answer

Mucinous adenocarcinoma

Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology — MCQs

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