Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology Indian Medical PG Practice Questions and MCQs

Question 61: A plain radiograph of the abdomen demonstrates gas within the bowel wall (pneumatosis). Which of the following would MOST likely be associated with this finding?

A. Air in the biliary tract
B. Blood in the biliary tract
C. Gas in the hepatic veins
D. Gas in the portal vein (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Gas in the portal vein** **Underlying Medical Concept:** The presence of gas within the bowel wall is termed **pneumatosis intestinalis**. When the integrity of the intestinal mucosa is compromised (due to ischemia, necrosis, or increased intraluminal pressure), gas enters the intramural space. From the bowel wall, this gas is drained by the mesenteric veins, which eventually carry it into the **portal venous system**. Therefore, pneumatosis intestinalis and portal venous gas are frequently seen together, particularly in life-threatening conditions like **Necrotizing Enterocolitis (NEC)** in neonates or mesenteric ischemia in adults. **Analysis of Incorrect Options:** * **A. Air in the biliary tract (Pneumobilia):** This is usually caused by a communication between the bowel and the bile duct (e.g., gallstone ileus, ERCP, or incompetent Sphincter of Oddi). Unlike portal gas, pneumobilia is typically located **centrally** near the hilum. * **B. Blood in the biliary tract (Hemobilia):** This presents with the triad of RUQ pain, jaundice, and GI bleed (Quincke's triad). It does not have a direct pathophysiological link to gas in the bowel wall. * **C. Gas in the hepatic veins:** This is a rare finding usually associated with trauma, gas-forming infections of the liver, or retrograde flow from the IVC. It is not a standard progression of pneumatosis intestinalis. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Appearance:** Portal venous gas is seen as branching radiolucencies extending to the **periphery** of the liver (carried by centrifugal blood flow), whereas pneumobilia is **central**. * **Most Common Cause (Neonates):** Necrotizing Enterocolitis (NEC). Look for the "Rigler sign" (gas on both sides of the bowel wall) if perforation occurs. * **Clinical Significance:** In the context of an acute abdomen, the combination of pneumatosis and portal venous gas is an ominous sign indicating bowel infarction.

Question 62: Which imaging modality is best for detecting focal liver lesions?

A. MRI (Correct Answer)
B. CT
C. USG
D. PET scan

Explanation: **Explanation:** **MRI (Magnetic Resonance Imaging)** is the gold standard for detecting and characterizing focal liver lesions. Its superiority lies in its **high soft-tissue contrast resolution** and the ability to use **Hepatobiliary-specific contrast agents** (e.g., Gadoxetate disodium/Primovist). These agents are taken up by functional hepatocytes, allowing for the differentiation between lesions containing hepatocytes (like FNH) and those that do not (like metastases or HCC), significantly increasing sensitivity and specificity. **Why other options are incorrect:** * **CT (Computed Tomography):** While excellent for staging and rapid assessment, CT has lower soft-tissue contrast than MRI. It relies heavily on vascularity patterns (Triple-phase CT) but may miss small or isodense lesions that MRI can easily detect. * **USG (Ultrasonography):** This is the **initial screening modality** of choice due to its cost-effectiveness and lack of radiation. However, it is operator-dependent and has limited sensitivity for very small lesions or lesions in cirrhotic livers. * **PET Scan:** Primarily used for detecting metabolic activity (metastases or recurrence). It is not the primary modality for initial detection or anatomical characterization of primary liver lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Best Initial Investigation:** USG. * **Best Modality for Characterization:** MRI. * **IOC for Hemangioma:** MRI (shows peripheral globular enhancement with "filling in"). * **IOC for HCC:** Triple-phase CT or Dynamic MRI (shows arterial enhancement with venous "washout"). * **Steatosis:** MRI (In-phase and Out-of-phase imaging) is the most sensitive for quantifying hepatic fat.

Question 63: What condition is characterized by a "bird beak" appearance?

A. Achalasia cardia (Correct Answer)
B. Carcinoma esophagus
C. Hiatus hernia
D. Diffuse esophageal spasm

Explanation: **Explanation:** **Achalasia Cardia (Correct Answer):** Achalasia is a primary esophageal motility disorder characterized by the failure of the Lower Esophageal Sphincter (LES) to relax and the absence of peristalsis in the distal esophagus. On a **Barium Swallow**, the classic finding is the **"Bird Beak" or "Rat Tail" appearance**. This represents a smooth, symmetric, tapered narrowing of the distal esophagus at the level of the gastroesophageal junction, with proximal esophageal dilatation (mega-esophagus). **Analysis of Incorrect Options:** * **Carcinoma Esophagus:** Typically presents with an **"Irregular Apple Core" appearance** or a "Shouldering effect." The narrowing is asymmetric, irregular, and has mucosal destruction, unlike the smooth tapering seen in Achalasia. * **Hiatus Hernia:** Characterized by the protrusion of the stomach through the diaphragmatic hiatus. Radiologically, it appears as a bulbous sac of barium above the diaphragm, often showing gastric mucosal folds. * **Diffuse Esophageal Spasm (DES):** Presents with uncoordinated, non-propulsive contractions. On Barium Swallow, this creates a **"Corkscrew Esophagus" or "Rosary Bead" appearance**. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Esophageal Manometry (shows incomplete LES relaxation and aperistalsis). * **Heller’s Myotomy:** The definitive surgical treatment. * **Chagas Disease:** A common secondary cause of Achalasia (caused by *Trypanosoma cruzi*). * **Sigmoid Esophagus:** The term used for the advanced, tortuous stage of esophageal dilatation in chronic Achalasia.

Question 64: Which is not a usual feature of Ulcerative colitis on barium enema?

A. Fine mucosal granularity
B. Pseudopolyps
C. Lead pipe colon
D. Colovesical fistula (Correct Answer)

Explanation: **Explanation:** The correct answer is **Colovesical fistula**. Ulcerative Colitis (UC) is a mucosal disease characterized by continuous inflammation limited to the mucosa and submucosa. Because it does not involve transmural inflammation, the formation of fistulae (such as colovesical or perianal fistulae) is extremely rare. Fistula formation is a hallmark of **Crohn’s Disease**, which involves transmural inflammation. **Analysis of Options:** * **Fine mucosal granularity (A):** This is the earliest radiological sign of UC on a double-contrast barium enema. It represents edema and hyperemia of the mucosa. * **Pseudopolyps (B):** These are islands of regenerating or normal mucosa surrounded by areas of extensive mucosal ulceration and depletion. They are a common feature of chronic UC. * **Lead pipe colon (C):** This refers to a featureless, narrowed, and shortened colon. It occurs in chronic stages due to the loss of haustral markings, longitudinal shortening, and muscular hypertrophy. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest sign on Barium Enema:** Fine mucosal granularity. * **Collar-button ulcers:** Deep ulcers formed when the inflammatory process undermines the mucosa (also seen in UC). * **Backwash Ileitis:** Involvement of the terminal ileum in UC (occurs in ~10% of cases of pancolitis); unlike Crohn's, the ileocecal valve is usually patent/incompetent. * **Toxic Megacolon:** A life-threatening complication of UC where the transverse colon diameter exceeds **6 cm** on plain X-ray.

Question 65: All of the following are signs of Hydatid Cyst except?

A. Camalote sign
B. Floating membrane sign
C. Ca wheel appearance
D. Mercedes Benz sign (Correct Answer)

Explanation: **Explanation:** The **Mercedes Benz sign** is the correct answer because it is a characteristic radiological feature of **cholelithiasis (gallstones)**, not hydatid disease. It represents the presence of triradiate, nitrogen-filled gas fissures within a gallstone, seen on a plain X-ray or CT scan. **Analysis of Hydatid Cyst Signs (Echinococcus granulosus):** * **Camalote sign (Water Lily sign):** This occurs when the endocyst ruptures, causing the germinal membrane to detach and float on the surface of the remaining cyst fluid. It is a classic sign seen on imaging (USG/CT/MRI). * **Floating membrane sign:** This is essentially the same mechanism as the Camalote sign, where detached membranes are seen undulating within the cyst cavity. * **Cartwheel (Ca wheel) appearance:** This occurs when multiple daughter cysts are arranged peripherally within the mother cyst, separated by internal septations (hydatid sand and matrix). This is characteristic of a **Type II hydatid cyst** (Gharbi classification). **High-Yield Clinical Pearls for NEET-PG:** * **Gharbi Classification:** Used to stage hydatid cysts (Type I: Pure fluid; Type II: Split wall/Membranes; Type III: Daughter cysts; Type IV: Solid/Heterogeneous; Type V: Calcified wall). * **Eggshell Calcification:** A common finding in the wall of a chronic hydatid cyst (Type V). * **Treatment:** The **PAIR** technique (Puncture, Aspiration, Injection of scolicidal agent, Re-aspiration) is a minimally invasive treatment option. * **Serology:** ELISA for Echinococcus IgG is the most common screening test.

Question 66: What is the characteristic appearance of a "Ca-wheel" on ultrasound?

A. Hydatid cyst (Correct Answer)
B. Intussusception
C. Hydatidiform mole
D. All of the above

Explanation: **Explanation:** The **"Cartwheel appearance"** (also known as the "spoke-wheel" or "honeycomb" appearance) is a classic radiological sign of a **Hydatid cyst** (caused by *Echinococcus granulosus*) on ultrasonography. This appearance occurs during the **WHO Stage CE2** (Active stage). It is produced by the presence of multiple **daughter cysts** separated by internal septations (representing the collapsed germinal membranes) within a larger mother cyst. **Why the other options are incorrect:** * **Intussusception:** Characteristically shows a **"Target sign"** or **"Donut sign"** on transverse sections and a **"Pseudokidney sign"** on longitudinal sections due to the telescoping of bowel loops. * **Hydatidiform mole:** Displays a characteristic **"Snowstorm appearance"** on ultrasound, caused by multiple hydropic villi appearing as tiny echogenic foci with interspersed cystic spaces. **High-Yield Clinical Pearls for NEET-PG:** 1. **Gharbi Classification:** Used for staging Hydatid cysts on USG. * **Type I:** Pure fluid collection (Anechoic). * **Type II:** Fluid collection with a split wall (**Water-lily sign** - detached endocyst). * **Type III:** Daughter cysts with septations (**Cartwheel/Honeycomb appearance**). * **Type IV:** Heterogeneous mass (Solid pattern). * **Type V:** Calcified wall (Inactive/Dead cyst). 2. **Treatment of Choice:** PAIR (Puncture, Aspiration, Injection, Re-aspiration) or surgical excision, usually covered with Albendazole. 3. **Serology:** ELISA is the most sensitive screening test for Hydatid disease.

Question 67: A 43-year-old woman presents with right upper quadrant abdominal pain and vomiting. She has had three children. The white blood cell count is 14.3x10^9/L and liver function tests are normal. What is the test of choice to establish the diagnosis in this patient?

A. Computerized axial tomography scan
B. Ultrasound (Correct Answer)
C. Hydroxy iminodiacetic acid scan
D. Magnetic resonance imaging scan

Explanation: **Explanation:** The clinical presentation of right upper quadrant (RUQ) pain, vomiting, and leukocytosis in a middle-aged woman (fitting the "4F" profile: Female, Forty, Fertile, Fat) is highly suggestive of **Acute Cholecystitis** or symptomatic cholelithiasis. **Why Ultrasound is the Correct Answer:** Ultrasound (USG) is the **initial investigation of choice** for suspected gallbladder disease. It has high sensitivity (>90%) and specificity for detecting gallstones and signs of inflammation. Key sonographic findings of acute cholecystitis include gallbladder wall thickening (>3 mm), pericholecystic fluid, and the **Sonographic Murphy’s sign** (maximal tenderness over the gallbladder when compressed by the probe), which has a high positive predictive value. **Analysis of Incorrect Options:** * **A. CT Scan:** While useful for detecting complications (like perforation or gangrene) or alternative diagnoses, it is less sensitive than USG for detecting gallstones and involves ionizing radiation. * **C. HIDA Scan (Hepatobiliary Iminodiacetic Acid):** This is the **most sensitive (Gold Standard)** test for diagnosing acute cholecystitis (showing non-visualization of the gallbladder). However, it is not the *initial* test of choice because it is time-consuming, expensive, and involves nuclear medicine. * **D. MRI/MRCP:** These are excellent for visualizing the biliary tree (choledocholithiasis) but are not first-line due to cost and lack of immediate availability. **NEET-PG High-Yield Pearls:** * **Initial test for RUQ pain:** Ultrasound. * **Most sensitive/Gold Standard for Acute Cholecystitis:** HIDA Scan. * **Best test for Choledocholithiasis (CBD stones):** MRCP (Non-invasive) or ERCP (Invasive/Therapeutic). * **WES Triad on USG:** Wall-Echo-Shadow (indicates a gallbladder packed with stones).

Question 68: Cobra head deformity in the lower end of ureter is seen in which of the following conditions?

A. Ureterocele (Correct Answer)
B. Vesical diverticula
C. Carcinoma of the urinary bladder
D. Urethral stricture

Explanation: **Explanation:** The **Cobra Head sign** (also known as the Adder head sign) is a classic radiological finding seen on an Intravenous Pyelogram (IVP) or Contrast CT, diagnostic of an **orthotopic ureterocele**. 1. **Why Ureterocele is correct:** A ureterocele is a congenital cystic dilatation of the distal-most intramural portion of the ureter. On a contrast study, the dilated ureter is filled with contrast (the "head"), which is surrounded by a thin, radiolucent halo representing the wall of the ureterocele and the bladder mucosa. This appearance mimics the hood of a cobra. 2. **Why other options are wrong:** * **Vesical diverticula:** These appear as contrast-filled outpouchings from the bladder wall (Hutch diverticulum), not as a filling defect within the bladder. * **Carcinoma of the urinary bladder:** This typically presents as an irregular, fixed filling defect. If it involves the ureteric orifice, it may cause hydroureter, but not the smooth, cystic "cobra head" appearance. * **Urethral stricture:** This is a narrowing of the urethra, best visualized on a Retrograde Urethrogram (RGU), and does not affect the distal ureteric morphology. **High-Yield Clinical Pearls for NEET-PG:** * **Simple (Orthotopic) Ureterocele:** Located at the normal vesicoureteric junction; usually seen in adults and produces the Cobra Head sign. * **Ectopic Ureterocele:** Located at the bladder neck or urethra; more common in children and often associated with a **duplicated collecting system** (Weigert-Meyer Law). * **Negative Cobra Head Sign:** If the radiolucent halo is thick or irregular, suspect a "pseudoureterocele," which can be caused by a stone impacted at the UVJ or a bladder tumor infiltrating the ureteric orifice.

Question 69: Radio-lucent renal stones are typically composed of which substance?

A. Cysteine
B. Calcium phosphate
C. Uric acid (Correct Answer)
D. All of the above

Explanation: ### 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).

Question 70: What is the diagnosis based on the ultrasound findings of an early pregnancy?

A. Partial mole
B. Complete mole (Correct Answer)
C. Invasive mole
D. Choriocarcinoma

Explanation: ***Complete mole*** - Shows the classic **"snowstorm"** or **"Swiss cheese"** appearance on ultrasound due to multiple **cystic spaces** representing hydropic villi. - **No fetal parts** or **fetal heart activity** are visualized, and **beta-hCG levels** are markedly elevated (>100,000 mIU/mL). *Partial mole* - Ultrasound shows **mixed echogenic pattern** with **focal cystic changes** and **fetal parts** may be present. - Associated with **triploid karyotype** (69,XXX or 69,XXY) and **lower beta-hCG levels** compared to complete mole. *Invasive mole* - **Cannot be diagnosed** by ultrasound alone as it appears similar to complete mole initially. - Diagnosis requires **histopathological evidence** of **myometrial invasion** and **persistently elevated beta-hCG** after evacuation. *Choriocarcinoma* - Ultrasound shows **heterogeneous mass** with **areas of hemorrhage** and **necrosis**, not the classic snowstorm pattern. - Develops after **any type of pregnancy** and shows **rapid metastatic spread** with **very high beta-hCG levels**.

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