Musculoskeletal Radiology Practice Questions

Q: A person has an injury to the forefinger with glass and it is suspected that there is a retained piece of glass in the finger. What is the first investigation you will perform?

Plain radiograph. **Explanation:** The correct answer is **Plain radiograph (X-ray)**. **Why Plain Radiograph is the Correct Choice:** In the context of suspected foreign bodies (FBs) following penetrating trauma, plain radiography is the **initial screening modality of choice**. A common misconception is that glass is only visible if it contains lead; however, **nearly all glass (90%+) is radiopaque** regardless of its lead content, provided it is at least 0.5–1.0 mm in size. X-rays are highly sensitive for detecting radiopaque materials like metal, glass, and gravel, and they are cost-effective and widely available. **Why Other Options are Incorrect:** * **Ultrasound:** While excellent for detecting **radiolucent** foreign bodies (like wood or thorns) and assessing soft tissue complications (abscess/tendon injury), it is operator-dependent and typically performed after a negative X-ray if clinical suspicion remains high. * **CT Scan:** CT is the most sensitive modality for localization but is reserved for complex cases, deep-seated fragments, or when X-ray and Ultrasound are inconclusive. It is not the "first" investigation due to higher radiation and cost. * **MRI:** MRI is generally **contraindicated** as the initial step because if the foreign body is metallic, the magnetic field can cause significant tissue damage by moving the fragment. **High-Yield Clinical Pearls for NEET-PG:** * **Radiopaque FBs:** Glass, metal, stone, and some bones (fish bones vary). * **Radiolucent FBs:** Wood, plastic, and most plant materials (best seen on USG). * **Rule of Thumb:** Always obtain at least **two orthogonal views** (Anteroposterior and Lateral) to accurately localize the depth of a foreign body. * **Lead Content:** The visibility of glass on X-ray does *not* depend on lead content; it depends on the physical density of the glass relative to the surrounding soft tissue.

Q: A 15-year-old female has an impacted tooth 23, located apical to teeth 22 and 24. How would an oral surgeon determine if the impacted tooth is positioned buccally or palatally to teeth 22 and 24?

Application of the SLOB rule. ### Explanation The correct answer is **C. Application of the SLOB rule.** The **SLOB rule (Same Lingual, Opposite Buccal)** is a fundamental radiographic principle used to determine the relative buccolingual position of objects within the jaws. It utilizes the concept of **parallax**, where the relative position of two objects changes when the angle of the X-ray beam is altered. * **Mechanism:** Two periapical radiographs are taken at different horizontal or vertical angulations. If the impacted tooth moves in the **same** direction as the X-ray tube head, it is located **Lingually (or Palatally)**. If it moves in the **opposite** direction, it is located **Buccally**. * **Clinical Application:** In this case, comparing a standard periapical view with a second view taken from a more mesial or distal angle allows the surgeon to localize tooth 23 precisely before surgical exposure. #### Why other options are incorrect: * **A. Waters view:** Primarily used to visualize the maxillary sinuses and midfacial fractures; it lacks the resolution and perspective for dental localization. * **B. Panoramic radiograph (OPG):** Provides a 2D overview of the entire dentition but cannot definitively distinguish between buccal and palatal positions due to its tomographic nature. * **D. Lateral head radiograph:** Useful for orthodontic assessment (Cephalometry), but teeth 22, 23, and 24 would be superimposed, making localization impossible. #### High-Yield NEET-PG Pearls: * **Clark’s Rule:** Another name for the SLOB rule (developed by CA Clark in 1910). * **Mnemonic:** **S**ame **L**ingual, **O**pposite **B**uccal. * **Modern Gold Standard:** While SLOB is the traditional radiographic method, **CBCT (Cone Beam Computed Tomography)** is now the clinical gold standard for 3D localization of impacted teeth. * **Tube Shift Technique:** The SLOB rule is also known as the "Tube Shift Technique" or "Buccal Object Rule."

Q: Lines shown in the above skull radiograph are a characteristic feature of which of the following conditions?

Sturge Weber syndrome.. ***Sturge Weber syndrome*** - Characterized by distinctive **"tram-track" double parallel curvilinear calcifications** on skull X-ray, representing calcified leptomeningeal angiomatosis. - These **serpentine calcifications** follow the brain surface convolutions and are pathognomonic for this neurocutaneous syndrome. *Paget's disease* - Shows **"cotton-wool" appearance** with mixed sclerotic and lytic lesions, not linear calcifications. - Demonstrates **skull thickening** and **enlarged diploic space**, creating a characteristic coarse trabecular pattern. *Albright syndrome* - Presents with **"ground-glass" appearance** due to fibrous dysplasia replacing normal bone architecture. - Shows **expansile lesions** with homogeneous density, not the linear calcifications seen in the radiograph. *Thalassemia* - Exhibits **"hair-on-end" appearance** due to extramedullary hematopoiesis causing perpendicular bone spicules. - Shows **widened diploic space** and **thinned outer cortex**, not serpentine calcifications.

Q: A radiograph of a girl's mandible shows a soap bubble appearance of a lytic lesion. On aspiration, the lesion yields blood. A whirring sound is heard from the lesion, and the girl can feel her heartbeat within it. What is the next recommended investigation?

CT Angiography. **Explanation:** The clinical presentation describes a **Central Arteriovenous Malformation (AVM)** of the mandible. The "soap bubble" appearance is a classic radiological sign of various lytic jaw lesions, but the definitive clues here are the **pulsatile nature** (feeling a heartbeat), the **audible bruit** (whirring sound), and the aspiration of **bright red blood**. 1. **Why CT Angiography is correct:** In the presence of a suspected vascular malformation or high-flow lesion (like an AVM), the primary goal is to map the feeding vessels and assess the extent of vascular involvement. **CT Angiography (CTA)** is the gold standard for visualizing the vascular architecture, planning surgical intervention, or preparing for therapeutic embolization. Performing a biopsy or curettage on such a lesion without prior vascular imaging can lead to life-threatening hemorrhage. 2. **Why other options are incorrect:** * **Non-contrast CT:** While excellent for assessing bone destruction, it cannot characterize the vascular flow or identify feeding arteries. * **CBCT (Cone Beam CT):** Provides high-resolution 3D images of dental structures and bone, but lacks the soft tissue and vascular contrast necessary to diagnose an AVM. * **MRI:** Useful for soft tissue extent, but CTA is generally preferred in the acute diagnostic phase for bony AVMs to specifically delineate the arterial supply for intervention. **Clinical Pearls for NEET-PG:** * **Differential for "Soap Bubble" Jaw Lesions:** Ameloblastoma (most common), Odontogenic Keratocyst (OKC), Giant Cell Granuloma, and AVM. * **High-Yield Sign:** Any lytic lesion of the jaw that exhibits a **bruit or pulsation** is a vascular malformation until proven otherwise. * **Management:** Pre-operative embolization followed by surgical resection is the standard treatment to prevent fatal bleeding.

Q: Which condition is characterized by the presence of ring-shaped epiphyses?

Osteogenesis imperfecta. **Explanation:** The correct answer is **Osteogenesis Imperfecta (OI)**. In patients with OI, particularly Type II and III, the epiphyses often appear as thin, radiopaque margins surrounding a lucent center. This radiological sign is known as **"Ring-shaped epiphyses"** or **"Halo epiphyses."** It occurs due to severe osteopenia and defective bone matrix formation, where the peripheral zone of calcification remains visible while the central portion is extremely demineralized. **Analysis of Incorrect Options:** * **Morquio Syndrome (MPS IV):** Characterized by **platyspondyly** (flat vertebrae) with a central anterior beak and irregular, fragmented epiphyses, but not specifically "ring-shaped." * **Zellweger Syndrome:** A peroxisomal disorder classically associated with **stippled epiphyses** (chondrodysplasia punctata), particularly in the patella and long bones. * **Multiple Epiphyseal Dysplasia (MED):** Characterized by delayed and irregular ossification of multiple epiphyses, leading to early-onset osteoarthritis, but the epiphyses are typically small and fragmented rather than ring-shaped. **High-Yield Clinical Pearls for NEET-PG:** * **Osteogenesis Imperfecta (OI):** Look for the triad of **blue sclera**, **fragile bones (multiple fractures)**, and **early deafness**. * **Radiological Signs in OI:** "Zebra-stripe sign" (following cyclical bisphosphonate therapy), "Popcorn calcifications" (metaphyseal/epiphyseal mineralization), and "Codfish vertebrae" (biconcave vertebrae). * **Stippled Epiphyses:** Remember the mnemonic **"CHUNZ"** (Chondrodysplasia punctata, Hypothyroidism, Warfarin embryopathy, Zellweger syndrome).

Q: A dense metaphyseal band is seen in which condition?

Hypervitaminosis D. **Explanation:** The presence of a **dense metaphyseal band** (also known as a "line of provisional calcification") is a classic radiological sign of **Hypervitaminosis D**. 1. **Why Hypervitaminosis D is correct:** Excessive Vitamin D leads to increased intestinal absorption of calcium and phosphorus. This results in hypercalcemia and hyperphosphatemia, which promotes excessive deposition of calcium salts at the zone of provisional calcification in the metaphysis. On X-ray, this appears as a thick, radiopaque (white) transverse band at the ends of long bones. 2. **Why the other options are incorrect:** * **Hypervitaminosis A:** Characterized radiologically by **subperiosteal new bone formation** (periostitis), particularly involving the shafts of long bones (ulna and metatarsals), and premature closure of epiphyses. * **Hypervitaminosis B:** There are no specific radiological bone findings associated with excess B-complex vitamins, as they are water-soluble and typically excreted. * **Scurvy (Vitamin C deficiency):** While Scurvy also features a dense line at the metaphysis (the **White Line of Fraenkel**), it is distinguished by other classic signs like the **Trummerfeld zone** (lucent scorbutic zone), **Pelkan spurs**, and **Wimberger’s ring sign** (dense rim around epiphysis). In the context of "Hypervitaminosis," Vitamin D is the primary culprit for dense bands. **NEET-PG High-Yield Pearls:** * **Hypervitaminosis D:** Look for "metastatic calcification" in soft tissues (kidneys, blood vessels). * **Lead Poisoning:** Also presents with dense metaphyseal bands ("Lead lines"), but these are usually seen in chronic ingestion and are most prominent at the knees and wrists. * **Amiodarone toxicity:** Can also cause dense metaphyseal bands in children. * **Hypothyroidism:** May show "stippled epiphyses" and delayed bone age.

Q: "Bone within bone" appearance is classically seen in?

Osteopetrosis. ### Explanation **Correct Answer: B. Osteopetrosis** **Mechanism:** Osteopetrosis (Albers-Schönberg disease or "Marble Bone Disease") is a genetic disorder characterized by **defective osteoclast function**. Because osteoclasts fail to resorb and remodel bone, there is a persistent accumulation of primary spongiosa within the marrow cavity. Radiographically, this creates a "dual-density" effect where a dense, smaller bone contour appears inside the normal bone cortex, classically termed the **"Bone-within-bone" appearance** (Endobone). This is most prominent in the vertebrae, pelvis, and short tubular bones. **Why other options are incorrect:** * **A. Osteomalacia:** Characterized by inadequate mineralization of the osteoid. The hallmark radiographic feature is **Looser’s zones** (pseudofractures), not increased density. * **C. Renal Osteodystrophy:** While it can cause increased bone density (Osteosclerosis), it typically presents as the **"Rugger-Jersey spine"** (increased density at the superior and inferior endplates) rather than a bone-within-bone appearance. * **D. Vitamin C Deficiency (Scurvy):** Presents with osteopenia and specific signs like the **Wimberger sign** (ring epiphysis), **Frankel’s line** (white line of scurvy), and **Pelkan spurs**, but not endobone formation. **High-Yield Clinical Pearls for NEET-PG:** * **Other causes of "Bone-within-bone":** Thorotrast administration, heavy metal poisoning (Lead), Hypervitaminosis D, and normal growth in infants. * **Erlenmeyer Flask Deformity:** Another classic sign of Osteopetrosis (also seen in Gaucher’s disease and Thalassemia). * **Clinical Paradox:** Despite being "dense" on X-ray, the bones in osteopetrosis are brittle and highly prone to fractures. * **Complications:** Bone marrow failure (pancytopenia) and cranial nerve palsies due to narrowing of the neural foramina.

Q: A young child presents with backache. Imaging reveals a solitary collapsed dorsal vertebra with preserved intervertebral disc spaces and no evidence of a soft tissue mass. What is the most likely diagnosis?

Langerhans cell histiocytosis. ### Explanation The clinical and radiological presentation described is classic for **Vertebra Plana** (Calvé disease), which is most commonly caused by **Langerhans Cell Histiocytosis (LCH)** in children. #### 1. Why Langerhans Cell Histiocytosis (LCH) is Correct LCH is the most common cause of a solitary collapsed vertebra in a child. The hallmark radiological finding is a symmetric, uniform collapse of the vertebral body, resulting in a "coin-on-edge" appearance. * **Preserved Disc Spaces:** Unlike infections (like Pott’s disease), LCH does not cross the disc space. * **No Soft Tissue Mass:** Unlike malignant tumors, LCH typically lacks a significant paraspinal soft tissue component. * **Reversibility:** A unique feature of LCH is that the vertebral height may partially or completely recover over time. #### 2. Why Other Options are Incorrect * **Lymphoma:** Usually presents with multiple levels of involvement, significant paraspinal soft tissue masses, and systemic symptoms (fever, weight loss). * **Ewing’s Sarcoma:** While it can cause vertebral collapse, it is typically associated with an aggressive, large, associated soft tissue mass and significant bone destruction. * **Metastases:** Rare in children (except Neuroblastoma). Metastases usually involve the pedicles (winking owl sign) and often affect multiple levels. #### 3. NEET-PG High-Yield Pearls * **Vertebra Plana Differential (Mnemonic: FEAL):** **F**racture (Eosinophilic Granuloma/LCH), **E**wing’s Sarcoma, **A**neurysmal Bone Cyst, **L**ymphoma/Leukemia. * **Most common site for LCH in spine:** Thoracic (Dorsal) vertebrae. * **Key differentiator from TB Spine:** In Tuberculosis, the intervertebral disc space is **destroyed** early, whereas in LCH, it is **preserved**. * **Skull finding in LCH:** "Punched-out" lytic lesions with beveled edges.

Q: Subcutaneous calcifications are seen in which of the following conditions?

Hyperparathyroidism. **Explanation:** **Hyperparathyroidism** (specifically secondary and tertiary forms) is a classic cause of **metastatic calcification**. In this condition, an elevated calcium-phosphate product leads to the deposition of calcium hydroxyapatite in soft tissues, including the subcutaneous layers. This is often seen radiologically as amorphous, cloud-like opacities in the periarticular and subcutaneous regions. **Analysis of Options:** * **Hyperparathyroidism (Correct):** Chronic renal failure leads to secondary hyperparathyroidism, which is the most common cause of extensive soft tissue and subcutaneous calcification (often termed *tumoral calcinosis* when large and periarticular). * **Gout (Incorrect):** While gout involves the deposition of monosodium urate crystals (tophi), these are typically **radiolucent** on standard X-rays unless they are very long-standing and have associated secondary calcium deposition. The primary pathology is not subcutaneous calcification but joint destruction and "punched-out" erosions. * **Ochronosis (Incorrect):** Also known as Alkaptonuria, this condition is characterized by the deposition of pigment in connective tissues. Radiologically, its hallmark is **dense disc space calcification** involving multiple levels of the spine and large joint arthropathy, not subcutaneous calcification. **NEET-PG High-Yield Pearls:** * **Differential Diagnosis for Subcutaneous Calcification:** Remember the mnemonic **"DISH-C"**: **D**ermatomyositis/Polymyositis, **I**diopathic, **S**cleroderma (CREST syndrome), **H**yperparathyroidism, and **C**alcinosis cutis. * **Monckeberg’s Sclerosis:** Another form of metastatic calcification seen in diabetics/renal patients, involving the tunica media of arteries. * **Ochronosis Key Sign:** "Vacuum phenomenon" in intervertebral discs followed by wafer-like calcification.

Q: Which imaging view best demonstrates inflammation and temporomandibular joint effusion?

T2 weighted MR images. **Explanation:** The **Temporomandibular Joint (TMJ)** is best evaluated using Magnetic Resonance Imaging (MRI) because it provides superior soft-tissue contrast for the articular disc and surrounding structures. **Why T2-weighted MRI is the correct answer:** In MRI physics, **T2-weighted images** are highly sensitive to water and fluid. Inflammation in the joint leads to increased capillary permeability and the accumulation of synovial fluid (effusion). On T2 sequences, this fluid appears as a **hyperintense (bright white)** signal. Therefore, T2-weighted MRI is the gold standard for detecting joint effusion, bone marrow edema, and active inflammatory changes in the TMJ. **Analysis of Incorrect Options:** * **B. T1-weighted MR images:** While T1 is excellent for demonstrating anatomical detail and the position of the articular disc (due to high signal from fatty marrow), it is poor at distinguishing fluid from surrounding soft tissues. * **C. Lateral tomogram:** This is a specialized radiographic technique used primarily to visualize bony anatomy and joint space. It cannot detect soft tissue inflammation or minor fluid collections. * **D. Panoramic radiograph (OPG):** This is a screening tool used to view the mandible and dentition. It lacks the resolution to visualize the TMJ disc or internal derangements and cannot detect effusion. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for TMJ Disc:** MRI (specifically T1 for anatomy/position). * **Gold Standard for TMJ Effusion:** T2-weighted MRI. * **Best for Bony Erosions:** Non-contrast CT (NCCT) or Cone Beam CT (CBCT). * **Closed vs. Open Mouth Views:** MRI is typically performed in both positions to assess the mobility and reduction of the articular disc.

Question 1

A person has an injury to the forefinger with glass and it is suspected that there is a retained piece of glass in the finger. What is the first investigation you will perform?

Accepted Answer

Plain radiograph

Answer

Ultrasound

Answer

CT scan

Answer

MRI

Question 2

A 15-year-old female has an impacted tooth 23, located apical to teeth 22 and 24. How would an oral surgeon determine if the impacted tooth is positioned buccally or palatally to teeth 22 and 24?

Accepted Answer

Application of the SLOB rule

Answer

Waters view

Answer

Panoramic radiograph

Answer

Lateral head radiograph

Question 3

Lines shown in the above skull radiograph are a characteristic feature of which of the following conditions?

Accepted Answer

Sturge Weber syndrome.

Answer

Paget's disease.

Answer

Albright syndrome.

Answer

Thalassemia.

Question 4

A radiograph of a girl's mandible shows a soap bubble appearance of a lytic lesion. On aspiration, the lesion yields blood. A whirring sound is heard from the lesion, and the girl can feel her heartbeat within it. What is the next recommended investigation?

Accepted Answer

CT Angiography

Answer

Non-contrast CT scan

Answer

CBCT

Answer

MRI

Question 5

Which condition is characterized by the presence of ring-shaped epiphyses?

Accepted Answer

Osteogenesis imperfecta

Answer

Morquio syndrome

Answer

Zellweger syndrome

Answer

Multiple epiphyseal dysplasia

Question 6

A dense metaphyseal band is seen in which condition?

Accepted Answer

Hypervitaminosis D

Answer

Hypervitaminosis A

Answer

Hypervitaminosis B

Answer

Scurvy

Question 7

"Bone within bone" appearance is classically seen in?

Accepted Answer

Osteopetrosis

Answer

Osteomalacia

Answer

Renal osteodystrophy

Answer

Vitamin C deficiency

Question 8

A young child presents with backache. Imaging reveals a solitary collapsed dorsal vertebra with preserved intervertebral disc spaces and no evidence of a soft tissue mass. What is the most likely diagnosis?

Accepted Answer

Langerhans cell histiocytosis

Answer

Lymphoma

Answer

Ewing's sarcoma

Answer

Metastases

Question 9

Subcutaneous calcifications are seen in which of the following conditions?

Accepted Answer

Hyperparathyroidism

Answer

Gout

Answer

Ochronosis

Answer

All of the above

Question 10

Which imaging view best demonstrates inflammation and temporomandibular joint effusion?

Accepted Answer

T2 weighted MR images

Answer

T1 weighted MR images

Answer

Lateral tomogram

Answer

Panoramic radiograph

Musculoskeletal Radiology — MCQs

Musculoskeletal Radiology — MCQs

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