NEET-PG 2012 - Radiology Practice Questions

Q: The most appropriate first-line imaging modality to detect adrenal metastasis due to bronchogenic carcinoma is:

Contrast Enhanced CT abdomen. **Contrast Enhanced CT abdomen** - **Contrast-enhanced CT abdomen** is generally considered the most sensitive and cost-effective imaging modality for detecting **adrenal metastases**. - It allows for detailed visualization of adrenal gland morphology, including size, shape, and enhancement patterns, which can help differentiate benign from malignant lesions. *PET scan* - While **PET (Positron Emission Tomography) scans** are highly sensitive for detecting metabolically active metastatic disease, they are often used as a secondary imaging modality to characterize indeterminate lesions found on CT or MRI. - **PET scans** can have false positives in benign adrenal tumors (e.g., adenomas rich in fat) and are less readily available or higher in cost for initial screening compared to CT. *MRI of the abdomen* - **MRI of the abdomen** can be very useful for further characterization of adrenal masses, especially for distinguishing between lipid-rich adenomas and metastases. - However, for initial detection, especially in the context of screening for distant metastases from bronchogenic carcinoma, **CT is generally preferred due to its wider availability, speed, and lower cost**. *Adrenal radionuclide scan* - **Adrenal radionuclide scans** (e.g., using MIBG or iodocholesterol) are primarily used for functional imaging of adrenal glands, typically to detect specific types of tumors like pheochromocytomas or aldosteronomas. - These scans are **not sensitive for detecting adrenal metastases** from bronchogenic carcinoma, as the metastatic lesions do not typically exhibit the specific uptake patterns targeted by these radiotracers.

Q: HU is a measure of

CT. ***Correct Answer: CT*** - HU stands for **Hounsfield Units**, a standardized quantitative scale used exclusively in **computed tomography (CT)** to describe the **radiodensity** of tissues based on **X-ray attenuation**. - On this scale, **water is assigned 0 HU**, air is -1000 HU, and dense bone can be +1000 HU or more. - This allows objective measurement and comparison of tissue densities across different CT scanners and examinations. *Incorrect: MRI* - **Magnetic Resonance Imaging (MRI)** does not use Hounsfield Units. - MRI signal intensity is based on the **magnetic properties of tissues** and local hydrogen proton density, not X-ray attenuation. *Incorrect: PET* - **Positron Emission Tomography (PET)** measures the metabolic activity of cells using **radioactive tracers**. - Its output is typically quantified in **Standardized Uptake Value (SUV)**, not Hounsfield Units. *Incorrect: USG* - **Ultrasound (USG)** imaging uses sound waves to create images of internal body structures. - It measures the **acoustic impedance** of tissues and displays findings in terms of echogenicity, not Hounsfield Units.

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: Which chamber enlargement shows a double right heart border with a wide subcarinal angle?

Left atrium. ***Left atrium*** - A **double right heart border** on a chest X-ray is a classic sign of **left atrial enlargement**, as the enlarged left atrium bulges into the right atrial silhouette. - The **wide subcarinal angle** (angle between the mainstem bronchi) also indicates left atrial enlargement, as the expanding left atrium pushes the bronchi apart. *Left ventricle* - **Left ventricular enlargement** primarily manifests as a **downward and leftward displacement of the apex** and increased cardiac silhouette on the left. - It does not typically cause a double right heart border or widening of the subcarinal angle. *Right atrium* - **Right atrial enlargement** usually presents as a **prominent right heart border** that extends further to the right than normal. - It does not result in a double right heart border or affect the subcarinal angle. *Right ventricle* - **Right ventricular enlargement** leads to an **anterior bowing of the sternum** (in severe cases) and an upward and leftward displacement of the cardiac apex. - It pushes the left ventricle posteriorly and does not produce a double right heart border or a wide subcarinal angle.

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: Which of the following conditions is least likely to cause posterior scalloping of the vertebrae?

Aortic aneurysm. ***Aortic aneurysm*** - An **aortic aneurysm** is located **anterior to the vertebral column** and primarily affects the anterior aspect of the vertebral bodies, causing **anterior scalloping** due to chronic pulsatile erosion, not posterior scalloping. - Posterior scalloping requires intraspinal pathology that expands the spinal canal from within; an aortic aneurysm is extraspinal and anterior, making it the **least likely** cause of posterior scalloping. *Neurofibromatosis* - **Neurofibromatosis** commonly causes posterior vertebral scalloping due to **dural ectasia** (widening of the dural sac) and pressure erosion from expanding neurofibromas within the spinal canal. - This condition is also associated with paraspinal masses, posterior vertebral body erosion, and scoliosis. *Astrocytoma* - An **intramedullary astrocytoma** within the spinal cord can lead to expansion of the cord that causes chronic pressure on the posterior vertebral bodies from within the spinal canal. - This slow-growing intraspinal tumor gradually remodels the bone, causing posterior scalloping. *Ependymoma* - Similar to astrocytoma, an **intramedullary ependymoma** (the most common primary intramedullary tumor in adults) can enlarge the spinal cord, leading to pressure erosion on the posterior vertebral bodies. - This is a characteristic feature of slowly growing intraspinal masses, which cause remodeling of the bony spinal canal.

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: 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

The most appropriate first-line imaging modality to detect adrenal metastasis due to bronchogenic carcinoma is:

Accepted Answer

Contrast Enhanced CT abdomen

Answer

PET scan

Answer

MRI of the abdomen

Answer

Adrenal radionuclide scan

Question 2

HU is a measure of

Accepted Answer

CT

Answer

MRI

Answer

PET

Answer

USG

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

Which chamber enlargement shows a double right heart border with a wide subcarinal angle?

Accepted Answer

Left atrium

Answer

Left ventricle

Answer

Right atrium

Answer

Right ventricle

Question 5

Step ladder pattern of gas shadow is seen in

Accepted Answer

Intestinal obstruction

Answer

Gastric outlet obstruction

Answer

Duodenal obstruction

Answer

Sigmoid volvulus

Question 6

Which of the following conditions is least likely to cause posterior scalloping of the vertebrae?

Accepted Answer

Aortic aneurysm

Answer

Astrocytoma

Answer

Neurofibromatosis

Answer

Ependymoma

Question 7

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 8

The longest half life is that of:

Accepted Answer

Uranium

Answer

Radon

Answer

Cesium

Answer

Radium

NEET-PG 2012 — Radiology