Radiologic landmarks Practice Questions

Q: A 42-year-old woman undergoes CT for evaluation of neck mass. The scan shows a 3 cm enhancing lesion at the carotid bifurcation that splays the internal and external carotid arteries (lyre sign). The lesion is located at the level of the C3-C4 vertebral bodies. Analyze the radiologic landmarks and anatomical relationships to identify this lesion.

Carotid body tumor (paraganglioma). ***Carotid body tumor (paraganglioma)*** - A highly vascular lesion located at the **carotid bifurcation** that classically splays the internal and external carotid arteries is known as the **lyre sign**, pathognomonic for this tumor. - It arises from **paraganglion cells** (chemoreceptors) located at the level of the **C3-C4 vertebral bodies**, appearing as a hypervascular enhancing mass on CT. *Thyroid nodule with lateral extension* - Thyroid nodules typically originate in the **visceral space** and move with swallowing; they do not cause wide splaying of the carotid arteries. - While they may be vascular, they are not typically centered precisely at the **carotid bifurcation** and do not exhibit the **lyre sign**. *Metastatic cervical lymph node* - Metastatic nodes (commonly from **squamous cell carcinoma**) are usually found along the **internal jugular vein** and do not typically splay the bifurcation. - These lesions often show **central necrosis** or irregular enhancement rather than the uniform, intense enhancement seen in paragangliomas. *Schwannoma of the vagus nerve* - A vagal schwannoma typically **displaces** both the internal and external carotid arteries **medially and anteriorly** as a single unit rather than splaying them apart. - These tumors are usually **less vascular** than carotid body tumors and lack the intense contrast enhancement characteristic of a paraganglioma. *Branchial cleft cyst* - This is a **cystic, fluid-filled lesion** typically located at the anteromedial border of the sternocleidomastoid muscle, not a solid enhancing mass. - It appears as a **non-enhancing** or thin-walled collection on CT and does not involve the carotid bifurcation or cause the **lyre sign**.

Question 1

A 25-year-old man presents with progressive weakness and urinary retention. MRI of the spine shows an intramedullary lesion from T10-T12 with expansion of the spinal cord and syrinx formation. The conus medullaris is identified at the L1-L2 level (normal: L1-L2). The filum terminale appears thickened at 3 mm. CSF flow study shows obstruction at the lesion site. Evaluate these radiologic landmarks and their relationships to determine the neurological level most likely affected.

Accepted Answer

Epiconus (T12-L1) with distal lower extremity and sphincter dysfunction

Answer

Cauda equina only, sparing upper motor neurons

Answer

Conus medullaris with mixed upper and lower motor neuron signs

Answer

Thoracic cord with pure upper motor neuron signs below T10

Answer

Lower thoracic nerve roots with radicular pain pattern only

Question 2

A 58-year-old woman with breast cancer undergoes staging CT. The scan shows a solitary 2 cm lesion in the liver at the junction of segments IVa, V, and VIII, directly adjacent to the middle hepatic vein. PET scan shows FDG avidity. The oncologist requests evaluation for surgical resection. The radiologist notes the lesion's relationship to the portal vein bifurcation (Cantlie's line). Evaluate the radiologic anatomical landmarks to determine resectability and surgical approach.

Accepted Answer

Central hepatectomy with middle hepatic vein reconstruction

Answer

Unresectable due to middle hepatic vein involvement; systemic therapy only

Answer

Right hepatectomy with adequate future liver remnant assessment

Answer

Extended right hepatectomy including segment IV

Answer

Radiofrequency ablation given central location

Question 3

A 33-year-old man presents after a motorcycle accident with pelvic pain. Pelvic radiograph shows widening of the pubic symphysis to 3.5 cm (normal: <1 cm) and disruption of Shenton's line on the left. The left sacroiliac joint appears widened compared to the right. CT shows a vertical shear fracture pattern. He is hypotensive at 85/50 mmHg despite 2L crystalloid. Evaluate the radiologic findings to determine the optimal management strategy.

Accepted Answer

Pelvic binder application with immediate transfer to angiography suite

Answer

External fixation in the emergency department followed by angiography

Answer

Immediate exploratory laparotomy for presumed hollow viscus injury

Answer

Emergent open reduction and internal fixation in the operating room

Answer

Continued resuscitation with repeat imaging in 2 hours

Question 4

A 42-year-old woman undergoes CT for evaluation of neck mass. The scan shows a 3 cm enhancing lesion at the carotid bifurcation that splays the internal and external carotid arteries (lyre sign). The lesion is located at the level of the C3-C4 vertebral bodies. Analyze the radiologic landmarks and anatomical relationships to identify this lesion.

Accepted Answer

Carotid body tumor (paraganglioma)

Answer

Schwannoma of the vagus nerve

Answer

Thyroid nodule with lateral extension

Answer

Metastatic cervical lymph node

Answer

Branchial cleft cyst

Question 5

A 70-year-old man with atrial fibrillation presents with acute abdominal pain. CT scan shows pneumatosis intestinalis in the right colon and gas in the portal venous system extending to within 2 cm of the liver capsule. The superior mesenteric artery is patent, but there is occlusion of the superior mesenteric vein. Analyze these radiologic landmarks to determine the most likely pathophysiologic mechanism.

Accepted Answer

Venous thrombosis with bowel edema and increased intraluminal pressure

Answer

Bacterial translocation from inflammatory bowel disease

Answer

Arterial embolic ischemia with transmural infarction

Answer

Non-occlusive mesenteric ischemia from low flow state

Answer

Bowel obstruction with bacterial overgrowth

Radiologic landmarks — MCQs

Radiologic landmarks — MCQs

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