Musculoskeletal Radiology Practice Questions

Q: Bone density is best studied by which imaging modality?

DEXA scan. **Explanation:** **1. Why DEXA Scan is the Correct Answer:** Dual-Energy X-ray Absorptiometry (DEXA) is the **gold standard** for measuring Bone Mineral Density (BMD). It utilizes two X-ray beams with different energy levels to differentiate between bone and soft tissue. Its clinical superiority stems from its high precision, low radiation dose (1/10th of a chest X-ray), and its ability to provide standardized **T-scores** and **Z-scores**, which are essential for diagnosing Osteoporosis and Osteopenia according to WHO criteria. **2. Why Other Options are Incorrect:** * **CT Scan:** While Quantitative CT (QCT) can measure bone density in 3D, a standard CT scan is not the primary tool due to significantly higher radiation exposure and cost. QCT is usually reserved for research or specific complex cases. * **MRI Scan:** MRI is excellent for visualizing soft tissues, bone marrow edema, and occult fractures, but it cannot accurately quantify mineral density because cortical bone yields a low signal (appears black). * **Bone Scan (Scintigraphy):** This functional imaging modality uses Technetium-99m MDP to detect **osteoblastic activity** (bone turnover). It is used to identify metastases, infections, or stress fractures, not to measure density. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sites for DEXA:** The most common sites measured are the **Lumbar spine (L1-L4)** and the **Proximal Femur (Neck of femur)**. * **T-score:** Compares patient BMD to a young healthy adult (30-year-old). * Normal: > -1.0 * Osteopenia: -1.0 to -2.5 * Osteoporosis: ≤ -2.5 * Severe Osteoporosis: ≤ -2.5 + fragility fracture. * **Z-score:** Compares patient BMD to an age-matched and sex-matched peer. A Z-score < -2.0 suggests secondary causes of bone loss.

Q: Trolly tract sign is seen in which of the following conditions?

Ankylosing spondylitis. **Explanation:** **Ankylosing Spondylitis (AS)** is the correct answer. The **Trolley Track sign** is a classic radiographic feature of advanced AS. It is caused by the ossification of the **supraspinous and interspinous ligaments**, which creates a central vertical radiodense line, combined with the ossification of the **apophyseal (facet) joint capsules**, which create two lateral vertical lines. Together, these three parallel lines resemble trolley tracks on a frontal (AP) X-ray of the spine. **Analysis of Incorrect Options:** * **Achondroplasia:** Characterized by "bullet-shaped" vertebrae, posterior scalloping, and a progressive narrowing of the interpedicular distance in the lumbar spine. * **Psoriatic Arthritis:** Typically shows "pencil-in-cup" deformities in the hands and asymmetrical sacroiliitis, but not the trolley track sign. * **Osteopetrosis:** Known for "Erlenmeyer flask" deformities and the "bone-within-a-bone" appearance (endobone) due to defective osteoclast activity. **High-Yield Clinical Pearls for NEET-PG:** * **Bamboo Spine:** Formed by marginal **syndesmophytes** (ossification of the outer fibers of the annulus fibrosus). * **Dagger Sign:** A single central radiodense line on AP X-ray due to ossification of the supraspinous and interspinous ligaments. * **Shiny Corner Sign (Romanus Lesion):** Early sign of AS representing small erosions at the corners of vertebral bodies. * **Andersson Lesion:** Non-infectious spondylodiscitis seen in AS. * **HLA-B27:** Strongly associated with AS (approx. 90% of cases).

Q: What is the best method to evaluate a discrepancy in the articular disc of the temporomandibular joint (TMJ)?

MRI. **Explanation:** The **Temporomandibular Joint (TMJ)** is a complex bicondylar joint containing a fibrocartilaginous articular disc. Evaluating "discrepancies" (such as internal derangement, disc displacement, or perforation) requires high-quality visualization of soft tissue structures. **Why MRI is the Correct Answer:** **MRI (Magnetic Resonance Imaging)** is the **gold standard** for TMJ evaluation. It provides superior soft-tissue contrast, allowing for the precise visualization of the articular disc, its position relative to the condyle (in both open and closed mouth positions), and the surrounding ligaments and muscles. It is non-invasive and does not use ionizing radiation. **Analysis of Incorrect Options:** * **Transpharyngeal projection (Parchman’s view):** This is a plain radiographic technique. While useful for identifying gross bony changes or fractures of the condyle, it cannot visualize the radiolucent articular disc. * **Arthrography:** This involves injecting contrast into the joint spaces. While it was historically used to diagnose disc perforations or adhesions, it is invasive and has been largely replaced by MRI. * **Arthroplasty:** This is a **surgical procedure** (treatment) to repair or replace the joint, not a diagnostic imaging method. **High-Yield Clinical Pearls for NEET-PG:** * **Best initial investigation for TMJ bony changes:** Non-contrast CT (NCCT) or Cone Beam CT (CBCT). * **Best investigation for TMJ soft tissue/disc:** MRI. * **Most common disc displacement:** Anterior displacement (often associated with "clicking" sounds). * **T1-weighted sequences** are excellent for anatomy, while **T2-weighted sequences** help identify joint effusion or inflammation.

Q: An oblique view in an X-ray of the hand is required for the diagnosis of which carpal bone?

Scaphoid. **Explanation:** The **Scaphoid** is the most commonly fractured carpal bone. Due to its unique anatomy and its 45-degree angulation relative to the long axis of the forearm, it is often obscured by other carpal bones on standard Anteroposterior (AP) and Lateral views. To visualize the scaphoid clearly and profile its waist (the most common site of fracture), a **Scaphoid series** is required. This includes a **PA view with ulnar deviation** and an **Oblique view** (typically 45 degrees). The oblique view projects the scaphoid away from the overlying trapezoid and trapezium, making it essential for diagnosing subtle cortical disruptions. **Analysis of Options:** * **Capitate (A):** The largest carpal bone, situated centrally. It is best visualized on standard AP and Lateral views; an oblique view is not the primary diagnostic requirement. * **Navicular (C):** This is an outdated anatomical term for the scaphoid. While technically the same bone, in modern medical examinations, "Scaphoid" is the preferred clinical term. * **Hamate (D):** While the body is seen on AP views, the **Hook of Hamate** requires specific views like the **Carpal Tunnel view** or a supinated oblique view, but it is not the classic answer for a standard oblique hand X-ray requirement. **High-Yield Clinical Pearls for NEET-PG:** * **Blood Supply:** The scaphoid receives its blood supply distally via the radial artery. Therefore, proximal pole fractures have a high risk of **Avascular Necrosis (AVN)** and non-union. * **Clinical Sign:** Tenderness in the **Anatomical Snuffbox** is the most sensitive clinical sign for a scaphoid fracture. * **Management:** If a fracture is clinically suspected but X-rays are negative, the wrist should be immobilized in a **thumb spica cast** and re-X-rayed after 10–14 days, or an MRI should be performed.

Q: What is seen in the X-ray of the femur below?

Codman's triangle. ***Codman's triangle*** - Represents **periosteal elevation** at the edge of an aggressive bone lesion, creating a triangular shadow on X-ray. - Commonly seen in **osteosarcoma** and other malignant bone tumors, indicating rapid tumor growth that lifts the periosteum. *Sunburst calcification* - Appears as **radiating spicules** of calcification extending outward from the bone surface like sun rays. - Characteristic of **osteosarcoma** but represents a different radiological pattern than the triangular shadow seen here. *Onion peel effect* - Shows **concentric layers** of periosteal reaction creating a laminated appearance around the bone. - Typically associated with **Ewing's sarcoma** rather than the single triangular elevation observed. *Bone marrow invasion* - Refers to **tumor infiltration** into the medullary cavity, not a specific X-ray finding. - Would appear as **lytic or sclerotic changes** within the bone rather than periosteal elevation.

Q: What is seen in the X-ray of the femur below?

Codman's triangle. ***Codman's triangle*** - **Codman's triangle** is a triangular area of new bone formation at the periphery of a bone tumor, typically seen in **aggressive bone lesions** like osteosarcoma. - It represents **reactive bone formation** where the periosteum is lifted by the expanding tumor, creating a characteristic triangular shadow on X-ray. *Sunburst calcification* - **Sunburst pattern** appears as radiating spicules of bone extending outward from the tumor, creating a "sun ray" appearance. - This pattern is typically seen in **osteosarcoma** but represents **tumor ossification** rather than periosteal reaction. *Onion peel effect* - **Onion peel** or **laminated periosteal reaction** shows multiple layers of new bone formation, resembling onion layers. - This pattern is classically associated with **Ewing's sarcoma** rather than the single triangular formation seen in Codman's triangle. *Bone marrow invasion* - **Bone marrow invasion** is a pathological process that cannot be directly visualized on **plain X-rays**. - This finding requires **MRI** or **CT imaging** to assess marrow signal changes and is not a specific radiographic sign.

Q: What is seen in the X-ray of the femur below?

Codman's triangle. ***Codman's triangle*** - A **triangular area of new bone formation** at the edge of a **periosteal reaction**, typically seen in aggressive bone tumors like **osteosarcoma**. - Represents the **periosteum being lifted** from the cortex by the underlying tumor, creating a characteristic triangular shadow on X-ray. *Sunburst calcification* - Characterized by **radiating spicules** of calcified tissue extending outward from the bone, creating a "sunburst" or "hair-on-end" appearance. - Also associated with **osteosarcoma** but represents a different radiological pattern of **perpendicular bone spicules** rather than periosteal lifting. *Onion peel effect* - Shows **multiple layers of periosteal reaction** creating concentric rings resembling an onion's layers on X-ray. - Classically associated with **Ewing's sarcoma** rather than osteosarcoma, representing repeated episodes of periosteal elevation and calcification. *Bone marrow invasion* - Refers to **tumor infiltration into the medullary cavity**, which is not directly visible on plain X-rays. - Requires **MRI or CT imaging** for proper visualization, as plain radiographs cannot adequately demonstrate marrow signal changes or soft tissue involvement.

Q: A radiograph of a 32-year-old patient reveals an asymptomatic lesion that was an accidental finding. What is the most likely diagnosis?

Stafne bone cavity. ***Stafne bone cavity*** - **Asymptomatic radiolucent lesion** commonly found as an **incidental radiographic finding** in the posterior mandible, typically below the **inferior alveolar canal**. - Represents a **developmental depression** in the lingual cortex of the mandible that contains **salivary gland tissue**, requiring no treatment. *Radicular cyst* - Most common **odontogenic cyst** that develops from **periapical granulomas** associated with **non-vital teeth**. - Typically presents with **symptoms** like pain, swelling, or history of **dental trauma/infection**, not as an incidental finding. *Dentigerous cyst* - Surrounds the **crown of an unerupted tooth**, most commonly **third molars** or **maxillary canines**. - Usually associated with **delayed tooth eruption** or **impacted teeth**, with clear relationship to tooth crown on radiographs. *Lateral periodontal cyst* - Small **odontogenic cyst** that develops along the **lateral root surface** of vital teeth. - Typically occurs in the **anterior mandible** or **premolar region**, not as a large posterior mandibular finding.

Q: Based on the provided MRI images of the knee (A and B), which show a well-defined fluid collection anterior to the patella, what is the most likely diagnosis?

Housemaid's knee. ***Housemaid's knee*** - The MRI shows fluid accumulation specifically in the **prepatellar bursa**, which is located anterior to the patella. This finding is the hallmark of prepatellar bursitis. - This condition is colloquially termed **"Housemaid's knee"** as it commonly results from chronic irritation and inflammation of the bursa due to repetitive kneeling. *Subdermal abscess* - A **subdermal abscess** would appear as a collection of pus in the subcutaneous tissue, often with irregular borders and significant surrounding **inflammatory changes (cellulitis)**, which are not the primary findings here. - The fluid collection is well-defined and confined to the anatomical location of the **prepatellar bursa**, not a disorganized subcutaneous collection. *Gout* - Gout typically presents as an acute **intra-articular** inflammation with a large joint effusion. Chronic gout can show characteristic **"rat-bite" erosions** on imaging, which are not visible here. - While gout can cause bursitis, the diagnosis is confirmed by identifying **negatively birefringent urate crystals** in aspirated fluid, and the imaging is less specific than for simple bursitis. *Rheumatoid arthritis* - Rheumatoid arthritis is a systemic disease causing **synovitis** and **pannus formation**, leading to joint destruction and bone erosions, none of which are seen in the image. - While bursitis can be associated with rheumatoid arthritis, it is typically part of a widespread **polyarthritis**, not an isolated finding as shown.

Question 1

Bone density is best studied by which imaging modality?

Accepted Answer

DEXA scan

Answer

CT scan

Answer

MRI scan

Answer

Bone scan

Question 2

Trolly tract sign is seen in which of the following conditions?

Accepted Answer

Ankylosing spondylitis

Answer

Achondroplasia

Answer

Psoriatic arthritis

Answer

Osteopetrosis

Question 3

What is the best method to evaluate a discrepancy in the articular disc of the temporomandibular joint (TMJ)?

Accepted Answer

MRI

Answer

Transpharyngeal projection

Answer

Arthrography

Answer

Arthroplasty

Question 4

A 76-year-old man presents with a lytic lesion in the vertebrae. X-ray of the skull showed multiple punched-out lesions. What is the most likely diagnosis?

Accepted Answer

Multiple myeloma

Answer

Metastasis

Answer

Osteomalacia

Answer

Hyperparathyroidism

Question 5

An oblique view in an X-ray of the hand is required for the diagnosis of which carpal bone?

Accepted Answer

Scaphoid

Answer

Capitate

Answer

Navicular

Answer

Hamate

Question 6

What is seen in the X-ray of the femur below?

Accepted Answer

Codman's triangle

Answer

Sunburst calcification

Answer

Onion peel effect

Answer

Bone marrow invasion

Question 7

What is seen in the X-ray of the femur below?

Accepted Answer

Codman's triangle

Answer

Sunburst calcification

Answer

Onion peel effect

Answer

Bone marrow invasion

Question 8

What is seen in the X-ray of the femur below?

Accepted Answer

Codman's triangle

Answer

Sunburst calcification

Answer

Onion peel effect

Answer

Bone marrow invasion

Question 9

A radiograph of a 32-year-old patient reveals an asymptomatic lesion that was an accidental finding. What is the most likely diagnosis?

Accepted Answer

Stafne bone cavity

Answer

Radicular cyst

Answer

Dentigerous cyst

Answer

Lateral periodontal cyst

Question 10

Based on the provided MRI images of the knee (A and B), which show a well-defined fluid collection anterior to the patella, what is the most likely diagnosis?

Accepted Answer

Housemaid's knee

Answer

Rheumatoid arthritis

Answer

Gout

Answer

Subdermal abscess

Musculoskeletal Radiology — MCQs

Musculoskeletal Radiology — MCQs

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