NEET-PG 2013 - Radiology Practice Questions

Q: "String of beads" appearance on horizontal abdominal view X-ray is suggestive of:

Small bowel obstruction. ***Small bowel obstruction*** - A "string of beads" appearance on a horizontal abdominal view X-ray refers to small gas bubbles trapped between the valvulae conniventes in a dilated small bowel loop. - This finding is highly suggestive of **complete small bowel obstruction**, particularly when accompanied by multiple air-fluid levels and dilated bowel loops. *Intussusception* - While it causes obstruction, intussusception usually appears as a **target sign** (doughnut sign) on ultrasound or a **meniscus sign** on barium enema, not a string of beads on plain X-ray. - Plain X-rays may show signs of **bowel obstruction**, but the string of beads is not characteristic. *Sigmoid volvulus* - Sigmoid volvulus is characterized by a **dilated loop of colon** forming an inverted U-shape, often described as a **coffee bean sign** or **omega sign**, on plain X-ray. - This involves the large bowel, and the "string of beads" specifically relates to gas in the small bowel. *Large bowel obstruction* - Large bowel obstruction typically presents with a **dilated colon** proximal to the obstruction and a collapsed distal colon, often with absent or minimal gas in the rectum and sigmoid. - While air-fluid levels can be present, the "string of beads" is a specific sign of gas within dilated small bowel loops, distinguishing it from most large bowel obstructions.

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: 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: 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: Which condition is associated with the pencil in cup deformity?

Psoriatic arthritis. ***Psoriatic arthritis*** - The **pencil-in-cup deformity** is a classic radiographic finding in advanced psoriatic arthritis, occurring due to **periarticular bone erosion** and phalangeal telescoping. - This specific deformity is characterized by the proximal phalanx eroding and fitting into the expanded distal phalanx, resembling a "pencil in a cup." *Rheumatoid arthritis* - While rheumatoid arthritis causes significant joint destruction, it typically presents with **periarticular erosions** and **joint space narrowing**, but not the characteristic pencil-in-cup morphology. - Common deformities include **swan-neck** and **boutonnière** deformities, and ulnar deviation. *Ankylosing spondylitis* - This condition primarily affects the **axial skeleton**, leading to spinal fusion and **sacroiliitis**. - Peripheral joint involvement is less common and typically does not result in the pencil-in-cup deformity; instead, it can cause **syndesmophytes**. *Avascular necrosis* - **Avascular necrosis** (AVN) involves the death of bone tissue due to lack of blood supply, primarily affecting the femoral head or other major joints. - Radiographic findings include **subchondral collapse**, crescent sign, and eventual joint destruction, but not the specific deformities seen in inflammatory arthritis like pencil-in-cup.

Q: In which condition is the 'Picture frame vertebra' seen?

Paget disease. ***Paget disease*** - The "picture frame vertebra" sign is a classic radiographic finding in **Paget disease**, characterized by **cortical thickening** and sclerosis around the vertebral body circumference, resembling a picture frame. - This appearance is due to the disordered bone remodeling processes (increased osteoclastic bone resorption followed by disorganized osteoblastic new bone formation) characteristic of Paget disease. *Osteopetrosis (marble bone disease)* - Osteopetrosis is characterized by **increased bone density** due to defective osteoclast function, leading to bones that are dense but brittle. - It does not typically present with the specific "picture frame" appearance of individual vertebrae, but rather with diffuse sclerosis of bones. *Ankylosing spondylitis (AS)* - Ankylosing spondylitis primarily affects the **axial skeleton**, causing inflammation and eventual fusion of the vertebrae (leading to a "bamboo spine" appearance). - While it involves the spine, it does not produce the "picture frame" vertebral sign seen in Paget disease. *Osteoporosis* - Osteoporosis is characterized by **reduced bone mass** and microstructural deterioration of bone tissue, leading to increased bone fragility and fracture risk. - Radiographically, it shows **decreased bone density** and possible vertebral compression fractures, which is the opposite of the increased bone density and cortical thickening seen in the "picture frame" sign.

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: 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: 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.

Question 1

"String of beads" appearance on horizontal abdominal view X-ray is suggestive of:

Accepted Answer

Small bowel obstruction

Answer

Intussusception

Answer

Sigmoid volvulus

Answer

Large bowel obstruction

Question 2

Frequency of ultrasound waves in USG -

Accepted Answer

>2 MHz

Answer

2000 Hz

Answer

5000 Hz

Answer

< 2 MHz

Question 3

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 4

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 5

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 6

Which condition is associated with the pencil in cup deformity?

Accepted Answer

Psoriatic arthritis

Answer

Rheumatoid arthritis

Answer

Ankylosing spondylitis

Answer

Avascular necrosis

Question 7

In which condition is the 'Picture frame vertebra' seen?

Accepted Answer

Paget disease

Answer

Osteopetrosis (marble bone disease)

Answer

Ankylosing spondylitis (AS)

Answer

Osteoporosis

Question 8

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 9

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 10

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

NEET-PG 2013 — Radiology