Abdominal and Pelvic Radiology Practice Questions

Q: What is the minimum size of a liver metastasis that can be detected by contrast-enhanced computed tomography (CECT)?

5 mm. **Explanation:** The detection of liver metastases on Contrast-Enhanced Computed Tomography (CECT) depends on the spatial resolution of the scanner and the contrast difference between the lesion and the surrounding liver parenchyma. * **Why 5 mm is correct:** Modern multidetector CT (MDCT) scanners, using thin-section collimation (typically 1–2 mm slices) and optimal intravenous contrast enhancement, have a high sensitivity for focal liver lesions. The practical threshold for reliable detection and characterization of a metastasis is **5 mm**. Lesions smaller than this often fall below the resolution limits or are obscured by "partial volume averaging," where the density of the small lesion is averaged with the surrounding healthy tissue. * **Why other options are incorrect:** * **1 mm:** This is below the spatial resolution of standard clinical CT. While micro-metastases exist, they cannot be visualized by current imaging modalities. * **1 cm:** While 1 cm lesions are easily seen, this is not the *minimum* size. CECT is significantly more sensitive than this. * **2 cm:** This was the threshold in the early days of single-slice CT. With modern technology, waiting for a lesion to reach 2 cm would represent a significant diagnostic delay. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** While CECT is the initial workup of choice, **MRI with hepatocyte-specific contrast agents (e.g., Gadoxetic acid/Primovist)** is the most sensitive modality for detecting small liver metastases (<1 cm). * **Vascularity:** Most liver metastases are **hypovascular** (e.g., Colorectal CA) and are best seen in the **portal venous phase**. * **Hypervascular Metastases:** Metastases from Renal Cell Carcinoma (RCC), Thyroid CA, Melanoma, and Neuroendocrine tumors are best seen in the **late arterial phase**. * **Hypodense Appearance:** On CECT, most metastases appear as well-defined hypodense areas relative to the enhancing liver.

Q: Comment on the diagnosis shown below?

Drooping water lily sign. ***Drooping water lily sign*** - This is the **classic radiological appearance** of a **hydatid cyst** (echinococcosis) where the detached **inner endocyst membrane** floats on fluid like a water lily on water surface. - Also known as the **camalote sign**, it indicates **cyst rupture** or **membrane detachment** and is pathognomonic for echinococcal cysts on imaging. *Horse shoe kidney* - This refers to a **congenital renal fusion anomaly** where both kidneys are connected at the lower poles, creating a horseshoe shape. - Typically shows **bilateral renal masses** connected across the midline with **malrotation** of the collecting systems. *Flower Vase kidney* - This describes the appearance of **chronic pyelonephritis** where there is **cortical scarring** overlying **dilated calyces**. - The kidney shows a **club-shaped calyceal dilatation** with overlying cortical thinning, resembling a flower vase shape. *Duplication of kidney* - This refers to **complete or incomplete duplication** of the **collecting system** with two separate ureters or a bifid ureter. - Shows **two distinct pelvicalyceal systems** within the same kidney, often with the upper pole ureter inserting ectopically.

Q: Which sonographic parameter is used to estimate intrauterine growth restriction?

Abdominal circumference. **Explanation:** **Abdominal Circumference (AC)** is the most sensitive and reliable single sonographic parameter for diagnosing and monitoring **Intrauterine Growth Restriction (IUGR)**. This is because IUGR (specifically asymmetric IUGR) primarily affects the liver size and the depletion of subcutaneous fat stores in the fetal abdomen. Since the liver is the first organ to show reduced growth due to glycogen depletion in a state of placental insufficiency, the AC will decrease before other skeletal measurements. **Analysis of Incorrect Options:** * **Femur Length (FL):** This is a measure of longitudinal skeletal growth. It is generally preserved in asymmetric IUGR ("head and limb sparing effect") and is more useful for determining gestational age in the second and third trimesters. * **Biparietal Diameter (BPD) & Head Circumference (HC):** These measure cranial growth. In asymmetric IUGR, fetal circulation prioritizes the brain (the "brain-sparing effect"), meaning these parameters often remain within normal limits while the body (AC) lags behind. **High-Yield Clinical Pearls for NEET-PG:** * **Best Parameter for Gestational Age (1st Trimester):** Crown-Rump Length (CRL). * **Best Parameter for Gestational Age (2nd/3rd Trimester):** Biparietal Diameter (BPD) or a composite of all four parameters. * **Asymmetric vs. Symmetric IUGR:** Asymmetric (most common) shows a high HC/AC ratio; Symmetric shows a normal HC/AC ratio as all parameters are equally reduced. * **Ponderal Index:** Used clinically to assess the severity of IUGR; it relates fetal weight to length.

Q: What is the diagnosis suggested by the barium X-ray findings?

Carcinoma of the esophagus. ***Carcinoma of the esophagus*** - Classic barium swallow findings include **irregular filling defect**, **shouldering**, and **mucosal destruction** with an **apple-core or rat-tail appearance**. - Shows **abrupt transition** from normal to abnormal mucosa, indicating **malignant stricture** with tissue destruction. *Achalasia* - Barium swallow demonstrates **smooth, symmetric bird-beak tapering** at the gastroesophageal junction without mucosal irregularity. - Shows **retained contrast** in a dilated esophagus due to **failure of lower esophageal sphincter relaxation**. *Plummer-Vinson Syndrome* - Characterized by a **smooth, thin postcricoid web** in the upper esophagus on barium swallow. - Associated with **iron deficiency anemia** and typically affects the **cervical esophagus**, not causing irregular filling defects. *Gastroesophageal reflux disease (GERD)* - Barium swallow may show **reflux of contrast** into the esophagus during fluoroscopy but **no structural lesion**. - May demonstrate **hiatal hernia** or **esophagitis** but lacks the irregular filling defect seen in malignancy.

Q: What is the first radiologic sign of Crohn's disease in the terminal ileum?

Aphthoid ulceration. **Explanation:** **1. Why Aphthoid Ulceration is Correct:** Aphthoid ulcers are the **earliest radiologic manifestation** of Crohn’s disease. Pathologically, these represent small, superficial erosions occurring over lymphoid follicles (Peyer's patches). On a double-contrast barium study, they appear as tiny "punched-out" collections of barium surrounded by a radiolucent halo of edema (the "target" or "bull’s eye" sign). Because Crohn’s is a transmural process that begins in the mucosa, these superficial lesions precede deeper ulceration and structural changes. **2. Analysis of Incorrect Options:** * **B. Pseudosacculation:** This is a **late/chronic sign**. It occurs due to asymmetrical involvement where one side of the bowel wall is scarred and fibrotic (shortened), while the opposite uninvolved border bulges out. * **C. Cobblestone pattern:** This represents a **more advanced stage**. It is caused by deep longitudinal and transverse ulcers intersecting, leaving islands of edematous, intact mucosa between them. * **D. Thickening of the bowel wall:** While common in Crohn’s due to transmural inflammation, it is a non-specific finding often seen on CT/USG and usually develops after the initial mucosal insults (aphthoid ulcers) have occurred. **3. NEET-PG High-Yield Pearls:** * **String Sign of Kantor:** Seen in the terminal ileum due to severe narrowing (spasm or fibrosis). * **Proud Flesh:** Inflammatory polyps/regeneration between ulcers. * **Creeping Fat:** Mesenteric fat wrapping around the bowel (classic surgical/CT finding). * **Skip Lesions:** Discontinuous involvement (unlike the continuous involvement in Ulcerative Colitis). * **Comb Sign:** Hypervascularity of the mesentery on CT, indicating active inflammation.

Q: Which of the following is true about OCG?

Ultrasound has replaced it. **Explanation:** **Oral Cholecystography (OCG)** was historically the gold standard for diagnosing cholelithiasis (gallstones). However, it has been almost entirely **replaced by Ultrasonography (USG)**. USG is the current investigation of choice because it is non-invasive, involves no radiation, does not require contrast ingestion, and has a higher sensitivity (>95%) for detecting gallstones, including those that are radiolucent. **Analysis of Options:** * **Option A:** This is historically incorrect. OCG was first performed by **Evarts Graham and Warren Cole in 1924**, not 1942. This was a landmark achievement in biliary imaging using phenoltetraiodophthalein. * **Option B:** The dye (typically **Iopanoic acid**) is not administered based on weight (1 ml/kg). The standard protocol involves oral ingestion of **3 grams** (usually six 0.5g tablets) the night before the procedure. * **Option C (Correct):** USG is superior as it can detect stones as small as 1-2 mm, visualize the gallbladder wall, and identify pericholecystic fluid—features OCG cannot reliably assess. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** OCG relies on the liver's ability to excrete the contrast into bile and the gallbladder's ability to concentrate it. * **Non-visualization on OCG:** If the gallbladder is not visualized after a double dose, it indicates a diseased gallbladder (e.g., chronic cholecystitis or cystic duct obstruction), provided liver function is normal (Bilirubin < 2-3 mg/dL). * **IOC (Investigation of Choice):** * Cholelithiasis: **USG** * Choledocholithiasis (Bile duct stones): **ERCP** (Gold standard/Therapeutic) or **MRCP** (Diagnostic) * Acute Cholecystitis: **HIDA Scan** (Most sensitive)

Question 1

What is the most common cause of widening of the C-loop of the duodenum?

Accepted Answer

Carcinoma of the head of the pancreas

Answer

Pancreatitis

Answer

Choledochal cyst

Answer

Retroperitoneal masses

Question 2

What is the minimum size of a liver metastasis that can be detected by contrast-enhanced computed tomography (CECT)?

Accepted Answer

5 mm

Answer

1 mm

Answer

1 cm

Answer

2 cm

Question 3

What is the investigation of choice for small bowel tumors?

Accepted Answer

Enterolysis

Answer

CT

Answer

Barium meal and follow through

Answer

MRI

Question 4

Which of the following imaging modalities can be used to detect carcinoma of the prostate gland?

Accepted Answer

CT Scan (Computed Tomography Scan)

Answer

PSA (Prostate-Specific Antigen)

Answer

MRI (Magnetic Resonance Imaging)

Answer

TRUS (Transrectal Ultrasound)

Question 5

Comment on the diagnosis shown below?

Accepted Answer

Drooping water lily sign

Answer

Horse shoe kidney

Answer

Flower Vase kidney

Answer

Duplication of kidney

Question 6

Which sonographic parameter is used to estimate intrauterine growth restriction?

Accepted Answer

Abdominal circumference

Answer

Femur length

Answer

Biparietal diameter (BPD)

Answer

Head circumference

Question 7

What is the diagnosis suggested by the barium X-ray findings?

Accepted Answer

Carcinoma of the esophagus

Answer

Achalasia

Answer

Plummer-Vinson Syndrome

Answer

Gastroesophageal reflux disease (GERD)

Question 8

What is the first radiologic sign of Crohn's disease in the terminal ileum?

Accepted Answer

Aphthoid ulceration

Answer

Pseudosacculation

Answer

Cobblestone pattern

Answer

Thickening of the bowel wall

Question 9

A 61-year-old man undergoes a CT scan study of the abdomen for unexplained abdominal distension. Low attenuation intraperitoneal collections with enhancing septae are demonstrated. There is scalloping of the liver border and omental thickening. Which one of the following is most likely to be the underlying cause?

Accepted Answer

Cystadenocarcinoma of the appendix

Answer

Carcinoid tumor of the appendix

Answer

Perforated duodenal ulcer

Answer

Spontaneous bacterial peritonitis

Question 10

Which of the following is true about OCG?

Accepted Answer

Ultrasound has replaced it

Answer

First done by Graham Cole in 1942

Answer

Dye ingested at a rate of 1 ml/kg

Answer

All of the above

Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology — MCQs

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