Abdominal and Pelvic Radiology Practice Questions

Q: What is the investigation of choice for chronic pancreatitis?

Endoscopic Retrograde Cholangiopancreatography (ERCP). **Explanation:** **Why ERCP is the Correct Answer:** Endoscopic Retrograde Cholangiopancreatography (ERCP) is traditionally considered the **gold standard** for diagnosing chronic pancreatitis because of its high sensitivity in detecting early ductal changes. It allows for the visualization of the "Chain of Lakes" appearance (alternating segments of dilation and stenosis in the main pancreatic duct). While MRCP is now the preferred non-invasive diagnostic tool, ERCP remains the "investigation of choice" in many classic MCQ formats due to its ability to provide detailed ductal anatomy and its therapeutic potential (stenting/stone removal). **Analysis of Incorrect Options:** * **A. Ultrasound (USG):** Often the initial screening tool. It can show calcifications or pseudocysts but lacks the sensitivity to detect early-stage chronic pancreatitis or subtle ductal changes. * **B. Abdominal X-ray:** Useful only for identifying **pancreatic calcifications** (seen in ~30% of cases), which is a pathognomonic sign. However, a negative X-ray does not rule out the disease. * **C. Barium Study:** This is obsolete for pancreatic pathology. It may indirectly show an "inverted 3 sign" (Frostberg’s sign) on the duodenum due to an enlarged pancreatic head, but it cannot diagnose the parenchyma or ducts. **High-Yield Clinical Pearls for NEET-PG:** * **Most sensitive non-invasive test:** Magnetic Resonance Cholangiopancreatography (MRCP) with Secretin enhancement. * **Most sensitive imaging for early changes:** Endoscopic Ultrasound (EUS). * **Pathognomonic finding:** Pancreatic calcifications on CT or X-ray. * **Classic Sign:** "Chain of Lakes" appearance (dilated duct with strictures). * **Triad of Chronic Pancreatitis:** Steatorrhea, Diabetes Mellitus, and Pancreatic Calcifications.

Q: Which imaging modality is best for detecting an abnormally located placenta?

Transvaginal sonography (TVS). **Explanation:** The gold standard for diagnosing an abnormally located placenta (Placenta Previa) is **Transvaginal Sonography (TVS)**. **1. Why TVS is the Correct Answer:** TVS provides superior resolution and allows for a more accurate measurement of the distance between the internal cervical os and the placental edge. Unlike other methods, it is not affected by maternal obesity or the position of the fetal head. It is proven to be safe and does not increase the risk of bleeding, provided the probe is not inserted into the cervical canal. **2. Why Other Options are Incorrect:** * **Transabdominal Sonography (TAS):** While often the initial screening tool, TAS has a high false-positive rate (up to 25%). It is limited by maternal habitus, acoustic shadowing from the fetal head, and "apparent" previa caused by an overdistended bladder compressing the lower uterine segment. * **Doppler Ultrasonography:** This is primarily used to detect **Placenta Accreta Spectrum** (morbidly adherent placenta) by visualizing hypervascularity at the bladder-uterine interface, rather than just the location of the placenta. * **MRI:** While highly accurate for posterior placentas and assessing the depth of invasion in accreta, it is expensive, not readily available, and reserved as a second-line modality when ultrasound results are inconclusive. **Clinical Pearls for NEET-PG:** * **Distance Rule:** A distance of **<2 cm** from the internal os defines a low-lying placenta; if it covers the os, it is placenta previa. * **Placental Migration:** A diagnosis of previa made in the first or second trimester often resolves by the third trimester due to the differential growth of the lower uterine segment. * **Safety:** TVS is the "Gold Standard" and is safe even in the presence of active vaginal bleeding.

Q: All of the following are radio-opaque stones except?

Uric acid. In radiology, the visibility of a urinary stone on a plain X-ray (KUB) depends on its effective atomic number and density. Stones with high calcium content or heavy minerals attenuate X-rays and appear **radio-opaque** (white), while those composed of organic compounds without heavy atoms are **radiolucent** (invisible on X-ray). **Explanation of the Correct Answer:** * **C. Uric acid:** These are the classic **radiolucent** stones. They are composed of organic material with a low atomic number, making them invisible on plain radiographs. However, they can be visualized as "filling defects" on IVP or clearly seen on Non-Contrast CT (NCCT), where they typically show low Hounsfield Units (400–600 HU). **Explanation of Incorrect Options:** * **A. Calcium (Oxalate/Phosphate):** These are the **most radio-opaque** stones due to the high atomic number of calcium. They are easily seen on plain X-rays. * **B. Struvite (Triple Phosphate):** Composed of Magnesium Ammonium Phosphate, these are radio-opaque (though less dense than pure calcium). They are often associated with Proteus infections and can form large **Staghorn calculi**. * **C. Cystine:** These are often described as **"faintly radio-opaque"** or having a "ground-glass" appearance. While less dense than calcium, they contain sulfur atoms, which provide enough attenuation to be visible on a plain film. **NEET-PG High-Yield Pearls:** 1. **Mnemonic for Opacity (Decreasing order):** **C**alcium > **S**truvite > **C**ystine > **U**ric acid/Xanthine (**C**an **S**ome **C**ats **U**nderstand?). 2. **Pure Radiolucent Stones:** Uric acid, Xanthine, and Indinavir (protease inhibitor) stones. 3. **Gold Standard Investigation:** **NCCT (Non-Contrast CT) KUB** is the investigation of choice for urolithiasis as it detects all stones (except Indinavir). 4. **Management:** Uric acid stones are unique because they can often be dissolved via **medical alkalization** of urine (pH > 6.5).

Q: What is the most accurate ultrasound method for assessing gestational age?

Crown-rump length. **Explanation:** The **Crown-Rump Length (CRL)** is the most accurate ultrasound parameter for dating a pregnancy. It is measured from the top of the fetal head (crown) to the bottom of the buttocks (rump) between **7 and 13 weeks + 6 days** of gestation. During this period, fetal growth is rapid and biological variation is minimal, allowing for a dating accuracy of within **±3 to 5 days**. **Analysis of Options:** * **Crown-Rump Length (CRL):** Correct. It is the gold standard for gestational age (GA) assessment in the first trimester. * **Gestational Sac Size (Mean Sac Diameter):** This is the earliest sign of pregnancy on USG (visible at ~5 weeks), but it is less accurate than CRL because sac shape can be distorted by bladder filling or uterine contractions. * **Femur Length (FL):** Along with Biparietal Diameter (BPD) and Abdominal Circumference (AC), this is used in the second and third trimesters. Accuracy decreases as pregnancy progresses (±2–3 weeks in the third trimester) due to genetic growth variations. * **Menstrual History (LMP):** While used to calculate the "Expected Date of Delivery" (Naegele’s rule), it is often unreliable due to irregular cycles, late ovulation, or poor patient recall. **High-Yield Clinical Pearls for NEET-PG:** * **First Trimester:** CRL is the most accurate. * **Second Trimester:** Biparietal Diameter (BPD) is the most common parameter used, but the combination of BPD, HC, AC, and FL is preferred. * **Rule of Thumb:** The earlier the ultrasound is performed, the more accurate the gestational age estimation. * **Transvaginal Sonography (TVS):** Can detect a gestational sac at a β-hCG level of **1,500–2,000 mIU/mL** (Discriminatory Zone).

Q: Reflex nephropathy is diagnosed mainly by:

Micturating cystourethrogram. **Explanation:** **Reflux Nephropathy (RN)** is the result of chronic renal scarring caused by the retrograde flow of infected urine from the bladder into the kidneys, secondary to **Vesicoureteral Reflux (VUR)**. **Why Micturating Cystourethrogram (MCUG) is the Correct Answer:** MCUG (also known as Voiding Cystourethrogram/VCUG) is the **gold standard investigation** for diagnosing and grading VUR. It allows for the real-time visualization of the retrograde flow of contrast from the bladder into the ureters and renal pelvis during micturition. Identifying the presence and severity of reflux is the definitive step in diagnosing the underlying cause of reflux nephropathy. **Analysis of Incorrect Options:** * **X-ray KUB:** This is a plain radiograph primarily used to detect radiopaque calculi. It cannot visualize the ureters, bladder dynamics, or the presence of reflux. * **CT Scan:** While CT can show renal scarring or thinning of the cortex, it is not the primary modality for diagnosing VUR and involves high radiation exposure, which is undesirable in the pediatric population where RN is most commonly diagnosed. * **MRI Scan:** MR Urography can show structural changes, but it is expensive, often requires sedation in children, and is not the first-line diagnostic tool for reflux. **High-Yield Clinical Pearls for NEET-PG:** * **DMSA Scan:** While MCUG diagnoses the *reflux*, a **99mTc-DMSA scan** is the most sensitive investigation to detect the resulting **renal scarring** (the "nephropathy" component). * **Classic Presentation:** A child presenting with recurrent Urinary Tract Infections (UTIs) and hypertension. * **Radiological Sign:** Look for "clubbing" of the calyces and overlying cortical thinning on intravenous pyelography (IVP). * **Grading:** VUR is graded I to V based on the extent of contrast ascent and ureteral dilatation seen on MCUG.

Q: Spider leg appearance is seen in which of the following conditions?

Adult polycystic kidney disease. **Explanation:** The **"Spider leg appearance"** is a classic radiological sign seen on an **Intravenous Pyelogram (IVP)** in patients with **Autosomal Dominant Polycystic Kidney Disease (ADPKD)**. This appearance occurs because multiple large, fluid-filled cysts within the renal parenchyma compress, stretch, and elongate the renal calyces and pelvis. On imaging, these thinned and elongated calyces resemble the long, spindly legs of a spider. **Analysis of Options:** * **A. Adult Polycystic Kidney Disease (Correct):** As described, the bilateral enlargement of the kidneys by numerous cysts distorts the collecting system into the characteristic spider-leg configuration. * **B. Wilm’s Tumor:** Typically presents with a **"Claw sign"** or a "Cup-and-spill" appearance. It causes displacement and distortion of the calyces, but usually in a localized, distorted mass effect rather than the symmetrical elongation seen in ADPKD. * **C. Horseshoe Kidney:** Characterized by the **"Flower vase appearance"** (or Handshaking sign) on IVP due to the abnormal axis of the kidneys and the low-lying, medially placed lower poles. * **D. Vesicoureteral Reflux (VUR):** Best diagnosed via **Voiding Cystourethrogram (VCUG)**. It shows retrograde flow of urine into the ureters and may lead to hydronephrosis or "clubbing" of calyces in chronic cases, but not a spider-leg appearance. **High-Yield Facts for NEET-PG:** * **ADPKD:** Associated with Berry aneurysms (Circle of Willis), hepatic cysts, and mitral valve prolapse. * **Swiss Cheese Appearance:** Seen on Nephrogram phase of IVP in **Autosomal Recessive** Polycystic Kidney Disease (ARPKD). * **Malignant Spider Leg:** Occasionally, large renal cell carcinomas can mimic this sign, but it remains the classic hallmark for ADPKD in exams.

Q: The "cut off" sign seen on imaging is characteristic of which of the following conditions?

Acute pancreatitis. ### Explanation The **"Colon Cut-off Sign"** is a classic radiographic finding associated with **Acute Pancreatitis**. **Why it occurs:** In acute pancreatitis, the inflammatory process and exudate spread from the pancreas into the **phrenicocolic ligament** via the transverse mesocolon. This inflammation causes localized spasm and functional obstruction (ileus) of the **splenic flexure** of the colon. On a plain abdominal X-ray, this appears as a gas-filled transverse colon that ends abruptly at the splenic flexure, with an absence of air in the descending and sigmoid colon. **Analysis of Incorrect Options:** * **B. Diverticulitis:** Typically presents with localized bowel wall thickening, pericolic fat stranding, or abscess formation on CT. It does not typically produce a proximal gas-distended colon with an abrupt distal cutoff. * **C. Appendicitis:** Common radiographic signs include a calcified appendicolith or a "sentinel loop" (localized ileus of the terminal ileum/cecum), but not the colon cut-off sign. * **D. Carcinoma of the colon:** While it causes mechanical obstruction with a transition point, the "colon cut-off sign" specifically refers to the **functional** ileus seen in inflammatory pancreatitis, not a physical neoplastic mass. **High-Yield Clinical Pearls for NEET-PG:** * **Sentinel Loop:** Another X-ray sign of acute pancreatitis, representing a localized ileus of a jejunal loop near the inflamed pancreas. * **Renal Halo Sign:** Peripancreatic fluid/edema outlining the kidneys, also seen in pancreatitis. * **Gold Standard Imaging:** Contrast-Enhanced CT (CECT) is the investigation of choice to assess the severity and complications (like necrosis) of pancreatitis, usually performed 48–72 hours after symptom onset.

Question 1

What is the investigation of choice for chronic pancreatitis?

Accepted Answer

Endoscopic Retrograde Cholangiopancreatography (ERCP)

Answer

Ultrasound (USG)

Answer

Abdominal X-ray

Answer

Barium study

Question 2

Which imaging modality is best for detecting an abnormally located placenta?

Accepted Answer

Transvaginal sonography (TVS)

Answer

Transabdominal sonography (TAS)

Answer

Doppler ultrasonography

Answer

Magnetic Resonance Imaging (MRI)

Question 3

All of the following are radio-opaque stones except?

Accepted Answer

Uric acid

Answer

Calcium

Answer

Struvite

Answer

Cystine

Question 4

What is the most accurate ultrasound method for assessing gestational age?

Accepted Answer

Crown-rump length

Answer

Femur length

Answer

Gestational sac size

Answer

Menstrual history

Question 5

Reflex nephropathy is diagnosed mainly by:

Accepted Answer

Micturating cystourethrogram

Answer

X-ray KUB

Answer

CT scan

Answer

MRI scan

Question 6

Spider leg appearance is seen in which of the following conditions?

Accepted Answer

Adult polycystic kidney disease

Answer

Wilm's tumor

Answer

Horseshoe kidney

Answer

Vesicoureteral reflux

Question 7

Imaging studies of a patient with a genetic disorder shows the 'central dot sign'. Which condition is characteristic of this finding?

Accepted Answer

Caroli's disease

Answer

Primary sclerosing cholangitis

Answer

Liver hemangioma

Answer

Polycystic liver disease

Question 8

Free gas in the abdomen, specifically under the diaphragm, can be best diagnosed by which radiographic view?

Accepted Answer

Standing view

Answer

Right lateral recumbent view

Answer

Left lateral recumbent view

Answer

Sitting position view

Question 9

Which of the following imaging findings is diagnostic of Adenomyosis?

Accepted Answer

Calcifications seen on CT scan.

Answer

Thickness of low signal intensity junctional zone >12mm on T2-weighted images.

Answer

Rain shower appearance of myometrium with coarsened echotexture.

Answer

Linear striations and subendometrial echogenic nodular appearance on USG.

Question 10

The "cut off" sign seen on imaging is characteristic of which of the following conditions?

Accepted Answer

Acute pancreatitis

Answer

Diverticulitis

Answer

Appendicitis

Answer

Carcinoma of the colon

Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology — MCQs

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