NEET-PG 2013 - Radiology Practice Questions

Q: The CT severity index in acute pancreatitis is described by:

Balthazar score. ***Balthazar score*** - The **Balthazar score** (or CT severity index) is a widely used radiological grading system for assessing the severity of **acute pancreatitis** based on findings on computed tomography (CT) scans. It evaluates both pancreatic inflammation and necrosis. - The Balthazar score helps predict the clinical course and potential complications of pancreatitis by assigning points for **pancreatic inflammation** and the extent of **necrosis**. *Mengini score* - The **Mengini score** is not a recognized CT severity index specifically for acute pancreatitis. - This name is not associated with any established scoring system in gastroenterology. *Chapman score* - The **Chapman score** refers to specific somatic points used in **osteopathic manipulative medicine** for diagnosis and treatment, primarily related to lymphatic system dysfunction. - It has no relevance to the radiological assessment or severity grading of acute pancreatitis. *Napelon score* - The **Napelon score** does not exist as a recognized medical scoring system, particularly in the context of acute pancreatitis or medical imaging. - This name is likely a distractor and not associated with medical practice.

Q: The most accurate investigation for assessing ventricular function is:

MRI. ***MRI*** - Cardiac MRI is considered the **gold standard** for assessing ventricular function, providing highly accurate and reproducible measurements of **ventricular volumes**, **ejection fraction**, and **myocardial mass**. - It offers excellent tissue characterization, allowing for direct visualization of **fibrosis**, **inflammation**, and other myocardial pathologies that can affect function. *Multislice CT* - While useful for assessing cardiac anatomy, particularly **coronary arteries**, Multislice CT involves **ionizing radiation** and has limitations in accurately assessing subtle changes in myocardial function compared to MRI. - Its strength lies more in **anatomical evaluation** (e.g., calcium scoring, coronary angiography) rather than detailed functional assessment. *Echocardiography* - Echocardiography is a widely available and useful first-line imaging modality for ventricular function, but it can be limited by **acoustic windows**, **operator dependency**, and **spatial resolution** compared to MRI. - While it provides good estimates of ejection fraction, particularly in simple cases, its 3D capabilities and tissue characterization are generally inferior to MRI. *Nuclear scan* - Nuclear scans (e.g., MUGA scans, SPECT) can assess ventricular function and myocardial perfusion, but they involve **ionizing radiation** and primarily provide **functional information** based on tracer uptake, not detailed structural or tissue characterization. - They are often used for evaluating **perfusion defects** and overall ejection fraction, but are less precise for detailed chamber quantification and tissue characterization than MRI.

Q: On imaging, diffuse axonal injury is characterized by -

Multiple small petechial hemorrhages. ***Multiple small petechial hemorrhages*** - Diffuse axonal injury (DAI) is characterized on imaging by numerous **small petechial hemorrhages** at the **gray-white matter junction**, **corpus callosum**, and **brainstem**. - These microhemorrhages are the **hallmark imaging finding** and are best visualized on MRI (GRE/SWI sequences), though they can be seen on CT as small hyperdensities. - This is the **most specific** and characteristic finding that defines DAI. *Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage* - While this description can be seen in DAI (combining edema with microhemorrhages), it is **less specific** and could represent other entities. - This mixed pattern is more commonly associated with **contusions** where there is more prominent parenchymal injury with larger areas of edema and hemorrhage. - DAI classically shows predominantly **small punctate hemorrhages** rather than larger patchy low-density lesions. *Crescentic extra-axial hematoma* - A crescentic extra-axial collection describes a **subdural hematoma**, which is an entirely separate entity from DAI. - Subdural hematomas are located between the dura and arachnoid membranes, whereas DAI involves direct **axonal shearing injury** within brain parenchyma. *White matter lucencies* - This is a **non-specific finding** that can occur in many conditions including ischemia, demyelination, and chronic small vessel disease. - While DAI can cause white matter edema leading to lucencies, this does not capture the **characteristic petechial hemorrhages** that define the condition on imaging.

Q: Which type of arthritis is characterized by the absence of a periosteal reaction?

Neuropathic arthritis. ***Neuropathic arthritis*** - **Neuropathic arthritis** (**Charcot joint**) is characterized by progressive joint destruction due to loss of proprioception and pain sensation, leading to severe bone and joint damage without a typical **periosteal reaction**. - The absence of normal protective reflexes results in repetitive microtrauma, often leading to bone resorption and fragmentation rather than new bone formation (periosteal reaction). *Psoriatic arthritis* - **Psoriatic arthritis** often presents with distinctive **periosteal reactions**, particularly at entheses and along the shafts of small bones (e.g., "pencil-in-cup" deformities and fluffy periostitis) [1]. - These periosteal changes are a hallmark of the inflammatory process affecting bone and connective tissues in psoriatic arthritis. *Rheumatoid arthritis* - **Rheumatoid arthritis** primarily involves the synovium, leading to erosions rather than prominent periosteal reactions in early stages [1]. - While periostitis can occur in chronic, destructive rheumatoid arthritis, it is not a primary or characteristic finding compared to other inflammatory arthritides. *Reactive arthritis* - **Reactive arthritis** frequently causes **periosteal reactions**, particularly at entheses (where tendons and ligaments attach to bone) and along the shafts of long bones, often described as "fluffy" periostitis [1]. - These new bone formations are a key radiological feature distinguishing it from other types of inflammatory arthritis.

Q: What is the CT scan finding in a carotid cavernous sinus fistula?

Enlarged superior ophthalmic vein. ***Enlarged superior ophthalmic vein*** * A carotid cavernous sinus fistula (CCSF) causes **high-pressure arterial blood** to shunt into the **venous system** of the cavernous sinus. * This increased pressure leads to retrograde flow and congestion in the draining veins, most notably the **superior ophthalmic vein**, causing its dilation. *Enlarged inferior ophthalmic vein* * While the inferior ophthalmic vein can also be involved in some cases of CCSF, the **superior ophthalmic vein** is typically more prominent and consistently affected due to its primary drainage pathway. * The inferior ophthalmic vein is less frequently the primary or most notable imaging finding compared to the superior ophthalmic vein. *Enlarged superior ophthalmic artery* * A CCSF involves an abnormal connection between the **carotid artery** (an artery) and the **cavernous sinus** (a venous structure), leading to venous, not arterial, dilation. * Arteries in the orbital region, like the superior ophthalmic artery, would not typically enlarge as a direct result of increased venous pressure in the cavernous sinus. *Enlarged inferior ophthalmic artery* * Similar to the superior ophthalmic artery, the inferior ophthalmic artery is an **arterial structure** and would not enlarge due to a high-flow arteriovenous shunt within the cavernous sinus. * The pathological changes in CCSF are primarily observed in the **venous drainage pathways**.

Q: Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?

Magnetic Resonance Imaging (MRI). ***Magnetic Resonance Imaging (MRI)*** - **MRI** is superior for differentiating epidermoid and arachnoid cysts due to its excellent **soft tissue contrast** and ability to detect fluid signal characteristics. - **Diffusion-weighted imaging (DWI)**, a specific MRI sequence, is crucial; **epidermoid cysts** show high signal on DWI (diffusion restriction) due to their keratin content, while **arachnoid cysts** follow CSF signal on all sequences and do not restrict diffusion. *Ultrasound (USG)* - **Ultrasound** has limited utility for intracranial lesions in adults due to the bony skull, which prevents sound wave penetration. - It may be used in infants through the fontanelles but lacks the resolution and specific sequences needed to characterize these cysts. *Computed Tomography (CT) scan* - While a **CT scan** can identify these cysts as hypodense lesions, it lacks the detailed **tissue characterization** and signal patterns provided by MRI. - Both cysts would appear as **hypodense lesions**, making differentiation difficult based on density alone, especially after contrast administration. *Positron Emission Tomography (PET) scan* - A **PET scan** primarily assesses metabolic activity and would not effectively differentiate between benign **non-metabolic cysts** like epidermoid and arachnoid cysts. - It is more commonly used for detecting **malignancies** or assessing brain activity patterns, not for structural differentiation of fluid-filled lesions.

Q: Which condition is characterized by a 'moth-eaten' appearance of the bones?

Multiple myeloma. ***Multiple myeloma*** [1][2] - Characterized by **punched-out lytic lesions** in bones, often described as **moth-eaten** appearance on imaging [1]. - Associated with **elevated serum proteins** and **Bence Jones proteins** in urine, confirming the diagnosis [2]. *Eosinophilic granuloma* - Usually presents with **solitary bone lesions** and is linked to **Langerhans cell histiocytosis** rather than the moth-eaten pattern. - Does not typically cause generalized **lytic bone lesions** seen in cases of multiple myeloma. *Chondromyxoid fibroma* - Generally appears as a **well-defined cortical lesion** and is not associated with a moth-eaten appearance. - It predominantly affects the **metaphysis** of long bones and shows a characteristic **cartilaginous matrix**. *Osteoid osteoma* - Presents with a **nidus** of osteoid formation, leading to localized bone pain, and does not exhibit a moth-eaten consistency. - Tends to cause **cortical bone thickening** rather than the diffuse lytic lesions associated with multiple myeloma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 608. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 616-617.

Q: Frequency of ultrasound waves in USG -

>2 MHz. ***>2 MHz*** - Medical diagnostic ultrasound typically uses frequencies in the **range of 2-15 MHz**, with some applications extending from 1-20 MHz. - Frequencies **above 2 MHz** are considered the standard for diagnostic ultrasonography, providing adequate **spatial resolution** and tissue penetration for imaging internal structures. - **Frequency selection** depends on the application: - **2-5 MHz**: Deep structures (abdominal, obstetric imaging) - better penetration - **5-10 MHz**: Vascular studies, cardiac imaging - **7-15 MHz**: Superficial structures (thyroid, breast, musculoskeletal) - better resolution - Higher frequencies provide better resolution but less penetration; the choice represents a trade-off based on clinical needs. *2000 Hz* - This frequency (2 kHz) falls within the **audible range** for humans (20 Hz to 20 kHz). - Such low frequencies would not provide the necessary **spatial resolution** for diagnostic imaging and lack the characteristics needed for medical ultrasound. *5000 Hz* - At 5 kHz, this is still within the **audible frequency range**. - These frequencies are far too low for medical ultrasound imaging, which requires **megahertz frequencies** to generate diagnostically useful images with adequate detail. * 20 kHz), are generally **below the diagnostic range** for most clinical applications. - Although lower frequencies offer better tissue penetration, frequencies below 2 MHz provide **insufficient spatial resolution** for standard diagnostic medical imaging.

Q: The Doppler effect in medical ultrasound is caused by:

Change in frequency of sound. ***Change in frequency of sound*** - The **Doppler effect** in medical ultrasound is fundamentally based on **frequency changes** that occur when sound waves reflect off moving structures like blood cells or tissues. - When ultrasound waves encounter moving objects, the frequency of reflected waves **shifts upward** (if moving toward transducer) or **shifts downward** (if moving away), enabling detection and measurement of blood flow and tissue movement. *Change in direction of sound* - While sound waves do change direction through **reflection** at tissue interfaces, this directional change doesn't explain the **frequency shift** characteristic of the Doppler effect. - Direction changes are related to **acoustic impedance** differences between tissues, not the motion-dependent frequency variations used in Doppler imaging. *Change in amplitude of sound* - Changes in **amplitude** relate to the **intensity** or strength of the sound waves, affected by factors like **attenuation** and **scattering**. - Amplitude variations don't create the **frequency shift** that allows Doppler ultrasound to detect moving structures and measure velocities. *None of the options* - This is incorrect because **frequency change** is indeed the correct mechanism underlying the Doppler effect in medical ultrasound. - The frequency shift phenomenon is what enables **color Doppler**, **pulsed-wave Doppler**, and **continuous-wave Doppler** imaging techniques to function.

Q: What is the standard radiation dose to point A in the cervix for brachytherapy in the treatment of cervical cancer?

8000 rad. ***8000 rad*** - The standard **total cumulative radiation dose** to **Point A** in the cervix for the treatment of cervical cancer is approximately **8000 rad (80 Gy)**. - This represents the **combined dose** from external beam radiation therapy (EBRT, typically 45-50 Gy) plus intracavitary brachytherapy (typically 30-40 Gy to Point A). - Point A is a classical reference point defined as **2 cm superior to the external cervical os and 2 cm lateral to the uterine canal**, representing the location where the uterine artery crosses the ureter. - This total dose aims to provide adequate tumor control while minimizing toxicity to surrounding organs like the bladder and rectum. *6000 rad* - A total dose of **6000 rad** is insufficient for definitive local control of cervical cancer. - This dose is below the therapeutic threshold and would result in significantly higher rates of local recurrence and treatment failure. - Adequate doses are essential for curative intent in cervical cancer management. *10000 rad* - A dose of **10000 rad** to Point A would be excessively high and significantly increase the risk of severe acute and late toxicities to surrounding tissues. - Such a high dose could lead to serious complications including **rectovaginal or vesicovaginal fistulas, proctitis, cystitis, bowel strictures, and tissue necrosis**. - The therapeutic window would be exceeded, causing more harm than benefit. *4000 rad* - A dose of **4000 rad** would be substantially lower than the standard therapeutic dose for cervical cancer. - This suboptimal dose would likely result in **inadequate tumor control and increased risk of local recurrence**. - It is far below the dose required for curative treatment of cervical cancer.

Question 1

The CT severity index in acute pancreatitis is described by:

Accepted Answer

Balthazar score

Answer

Mengini score

Answer

Chapman score

Answer

Napelon score

Question 2

The most accurate investigation for assessing ventricular function is:

Accepted Answer

MRI

Answer

Multislice CT

Answer

Echocardiography

Answer

Nuclear scan

Question 3

On imaging, diffuse axonal injury is characterized by -

Accepted Answer

Multiple small petechial hemorrhages

Answer

Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage

Answer

Crescentic extra-axial hematoma

Answer

White matter lucencies

Question 4

Which type of arthritis is characterized by the absence of a periosteal reaction?

Accepted Answer

Neuropathic arthritis

Answer

Psoriatic arthritis

Answer

Rheumatoid arthritis

Answer

Reactive arthritis

Question 5

What is the CT scan finding in a carotid cavernous sinus fistula?

Accepted Answer

Enlarged superior ophthalmic vein

Answer

Enlarged inferior ophthalmic vein

Answer

Enlarged superior ophthalmic artery

Answer

Enlarged inferior ophthalmic artery

Question 6

Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?

Accepted Answer

Magnetic Resonance Imaging (MRI)

Answer

Ultrasound (USG)

Answer

Computed Tomography (CT) scan

Answer

Positron Emission Tomography (PET) scan

Question 7

Which condition is characterized by a 'moth-eaten' appearance of the bones?

Accepted Answer

Multiple myeloma

Answer

Osteoid osteoma

Answer

Eosinophilic granuloma

Answer

Chondromyxoid fibroma

Question 8

Frequency of ultrasound waves in USG -

Accepted Answer

>2 MHz

Answer

2000 Hz

Answer

5000 Hz

Answer

< 2 MHz

Question 9

The Doppler effect in medical ultrasound is caused by:

Accepted Answer

Change in frequency of sound

Answer

Change in direction of sound

Answer

Change in amplitude of sound

Answer

None of the options

Question 10

What is the standard radiation dose to point A in the cervix for brachytherapy in the treatment of cervical cancer?

Accepted Answer

8000 rad

Answer

6000 rad

Answer

10000 rad

Answer

4000 rad

NEET-PG 2013 — Radiology