NEET-PG 2012 - Radiology Practice Questions

Q: Which of the following appears the same on both T1 and T2 weighted MRI sequences?

Fat. ***Fat*** - On both T1 and T2 weighted MRI sequences, fat appears **bright** (high signal intensity). - This consistent bright signal makes fat a useful internal reference point for signal interpretation. *Gall bladder* - The gall bladder is filled with **bile**, which appears bright on T2-weighted images due to its high water content, but can be variable on T1. - Bile does not maintain consistently the **same signal intensity** as fat on both sequences. *Kidney* - The renal parenchyma typically has **intermediate signal intensity** on both T1 and T2, but its signal characteristics are different from the consistently bright signal of fat. - The signal can vary depending on the specific sequence parameters and hydration status, unlike fat. *CSF* - **Cerebrospinal fluid (CSF)** appears dark (low signal) on T1-weighted images and bright (high signal) on T2-weighted images due to its high water content. - This distinct signal intensity difference between T1 and T2 is contrary to the shared bright appearance of fat on both sequences.

Q: Which of the following features is used to identify the colon on an X-ray?

Haustra. ***Haustra (Correct Answer)*** - **Haustra** are sacculations or pouches of the colon created by the uneven contraction of the **taeniae coli** - They are THE characteristic feature that helps distinguish the large bowel from the small bowel on an X-ray - These indentations typically do **not cross the entire width** of the bowel lumen, unlike the valvulae conniventes of the small intestine - Haustra appear as incomplete septations on plain radiographs *Valvulae conniventes (Incorrect)* - **Valvulae conniventes** (also known as plicae circulares) are large, circular folds of the **small intestine** mucosa that project into the lumen - They extend **completely across the lumen** of the small bowel, making them easily distinguishable from haustra which only partially traverse the colon - This is a feature of small bowel, not colon *String of beads sign (Incorrect)* - The "**string of beads sign**" is a **pathological radiographic finding** associated with small bowel obstruction - It refers to multiple small, gas-filled loops of small bowel stacked on top of each other, often with small pockets of fluid or air trapped between the folds, resembling beads on a string - This is not a normal anatomical feature used to identify the colon *More number of loops (Incorrect)* - The number of loops is **not a primary distinguishing feature** between the large and small bowel on an X-ray - While the small intestine generally has more convolutions or loops than the colon, this is a **less reliable and specific sign** compared to the presence of haustra - Haustra remain the gold standard feature for colon identification

Q: Investigation of choice for studying Renal Cortical mass

99mTc DMSA. ***99mTc DMSA*** - **99mTc DMSA** (Technetium-99m dimercaptosuccinic acid) is the radiopharmaceutical of choice for imaging the **renal cortex** and assessing **renal cortical mass** and scarring. - It binds preferentially to the cells of the **renal tubules**, allowing for excellent visualization of cortical tissue. *99mTc DTPA* - **99mTc DTPA** (Technetium-99m Diethylenetriaminepentaacetic acid) is primarily used to assess **glomerular filtration rate (GFR)** and renal blood flow. - It is filtered by the **glomeruli** but not reabsorbed or secreted by the tubules, making it suitable for functional studies rather than morphological assessment of cortical mass. *53Cr Study* - **53Cr** (Chromium-51) is used in studies to measure **red blood cell mass**, survival, or gastrointestinal protein loss. - It has no role in the direct assessment of **renal cortical mass** or function. *99mTc Pyrophosphate* - **99mTc Pyrophosphate** is primarily used to evaluate **myocardial infarction** (hot spots) or detect bone lesions. - It is not indicated for, nor does it provide useful information about, **renal cortical mass**.

Q: Investigation of choice for intramedullary SOL is -

MRI. ***MRI*** - **Magnetic Resonance Imaging (MRI)** is the investigation of choice for intramedullary lesions due to its superior **soft tissue contrast** and ability to visualize the **spinal cord** parenchyma. - It provides detailed information on lesion size, location, and internal characteristics, which is crucial for diagnosis and surgical planning. *USG* - **Ultrasound (USG)** has limited utility for intramedullary lesions as a primary diagnostic tool because **bone impedes sound waves**, making it difficult to visualize structures within the spinal canal. - It might be used for neonatal spinal screening or intraoperative guidance, but not for definitive diagnosis of intramedullary lesions in adults. *CT* - **Computed Tomography (CT)** excels at visualizing **bone structures** and calcifications, but it provides less detailed information about soft tissue elements like the spinal cord compared to MRI. - While it can identify bony changes associated with intramedullary lesions, it is not the preferred initial imaging modality for characterizing the lesion itself. *X-ray* - **X-rays** provide basic imaging of bone but offer essentially **no visualization of soft tissues** such as the spinal cord or intramedullary lesions. - They are primarily used to identify gross bony abnormalities like fractures or severe degenerative changes, not for subtle intraspinal pathologies.

Q: A polytrauma patient's CT brain shows a crescent-shaped extra-axial collection with a concave inner margin. What is the most likely diagnosis?

SDH. ***SDH*** - The image shows a **crescent-shaped collection** of hemorrhage with a concave inner margin, consistent with a **subdural hematoma** (SDH). - SDHs result from the tearing of **bridging veins** and typically conform to the brain's surface, crossing suture lines but not limited by bony sutures. *EDH* - An **epidural hematoma (EDH)** characteristically appears as a **lenticular** or **biconvex** shape on CT, not crescent-shaped. - EDHs are typically caused by arterial bleeding, often from the **middle meningeal artery**, and are limited by cranial sutures. *Contusion* - A **contusion** is brain tissue bruising that appears as **heterogeneous areas** of hemorrhage and edema within the brain parenchyma itself. - It would not manifest as a distinct extra-axial collection with a smooth, concave margin. *Diffuse axonal injury* - **Diffuse axonal injury (DAI)** involves widespread microscopic damage to axons, often at the gray-white matter junction. - It may appear as *punctate hemorrhages* or **small lesions** at these junctions on CT, but often the CT can be normal, and it would not present as a large extra-axial collection.

Q: Step ladder pattern of gas shadow is seen in

Intestinal obstruction. ***Intestinal obstruction*** - A **step-ladder pattern** of gas shadows is a classic radiological sign seen in **small bowel obstruction** due to dilated, fluid-filled loops of small bowel stacked on top of each other. - This pattern results from the accumulation of gas and fluid proximal to the obstruction, causing dilated bowel loops to arrange horizontally. *Gastric outlet obstruction* - This condition primarily results in a **dilated stomach** with fluid and gas, not typically a step-ladder pattern in the small bowel. - Vomiting is usually a prominent symptom, and imaging would show a large fluid-filled stomach. *Duodenal obstruction* - Causes dilatation of the stomach and duodenum, leading to a "**double-bubble sign**" (dilated stomach and proximal duodenum). - It does not typically produce the extensive, stacked small bowel loops seen in a step-ladder pattern. *Sigmoid volvulus* - Characterized by a distinctive large, dilated loop of sigmoid colon, often described as a "**coffee bean sign**" or an **inverted U-shape**. - This is a large bowel obstruction and does not typically present with a step-ladder pattern of small bowel gas.

Q: Parrot beak appearance is seen in which of the following conditions?

Volvulus. ***Volvulus*** - A **parrot beak** appearance, or bird's beak sign, is characteristic of a **volvulus** on barium enema or CT imaging, representing the twisted lumen of the bowel. - This finding indicates a **torsion** of a segment of the bowel, which can lead to obstruction and ischemia. *Intussusception* - Intussusception typically presents with a **"target sign"** or **"donut sign"** on ultrasound, indicating concentric layers of bowel within bowel. - The classic presentation is a **"currant jelly stool"** and a palpable **sausage-shaped mass**. *Rectal atresia* - Rectal atresia involves a **complete blockage** or absence of the rectum, preventing passage of stool. - Imaging typically shows a **dilated colon** proximal to the atretic segment, without a specific "parrot beak" appearance. *CA colon* - Colon cancer (CA colon) appears as a **filling defect** or an **"apple core" lesion** on barium enema due to tumoral constriction. - It does not present with a "parrot beak" sign, which is indicative of a twisted bowel segment.

Q: The longest half life is that of:

Uranium. ***Uranium*** - **Uranium-238**, a common isotope, has an incredibly long half-life of approximately **4.468 billion years**, which is comparable to the age of the Earth. - This extremely long half-life is due to its slow **alpha decay**, making it a very stable radioactive element. *Radon* - **Radon-222** has a relatively short half-life of about **3.8 days**. - Its short half-life makes it a significant indoor air pollutant as it rapidly decays into other radioactive isotopes. *Cesium* - **Cesium-137**, a product of nuclear fission, has a half-life of approximately **30 years**. - While longer than radon, its half-life is much shorter compared to uranium, meaning it decays significantly faster. *Radium* - **Radium-226**, a decay product of uranium, has a half-life of approximately **1,600 years**. - Although much longer than radon and cesium, it is still orders of magnitude shorter than the half-life of uranium-238.

Question 1

Which of the following appears the same on both T1 and T2 weighted MRI sequences?

Accepted Answer

Fat

Answer

Gall bladder

Answer

Kidney

Answer

CSF

Question 2

Which of the following features is used to identify the colon on an X-ray?

Accepted Answer

Haustra

Answer

Valvulae conniventes

Answer

String of beads sign

Answer

More number of loops

Question 3

Investigation of choice for studying Renal Cortical mass

Accepted Answer

99mTc DMSA

Answer

99mTc DTPA

Answer

53Cr Study

Answer

99mTc Pyrophosphate

Question 4

Investigation of choice for intramedullary SOL is -

Accepted Answer

MRI

Answer

USG

Answer

CT

Answer

X-ray

Question 5

A polytrauma patient's CT brain shows a crescent-shaped extra-axial collection with a concave inner margin. What is the most likely diagnosis?

Accepted Answer

SDH

Answer

EDH

Answer

Contusion

Answer

Diffuse axonal injury

Question 6

Step ladder pattern of gas shadow is seen in

Accepted Answer

Intestinal obstruction

Answer

Gastric outlet obstruction

Answer

Duodenal obstruction

Answer

Sigmoid volvulus

Question 7

Parrot beak appearance is seen in which of the following conditions?

Accepted Answer

Volvulus

Answer

Rectal atresia

Answer

CA colon

Answer

Intussusception

Question 8

The longest half life is that of:

Accepted Answer

Uranium

Answer

Radon

Answer

Cesium

Answer

Radium

NEET-PG 2012 — Radiology