Computed Tomography Test Computed Tomography (CT Brain) 4 — Questions and Answers
Question 1: A CT brain performed for trauma shows a lens-shaped (biconvex) hyperdense collection between the inner table of the skull and the brain. The most likely source of bleeding is:
- Middle meningeal artery (Correct answer)
- Bridging cortical veins
- Anterior cerebral artery
- Vertebral artery
Correct answer: Middle meningeal artery
Epidural hematomas are most commonly caused by tearing of the middle meningeal artery, producing the classic biconvex hyperdense collection.
Question 2: On CT perfusion imaging of the brain, 'ischemic penumbra' refers to tissue with:
- Reduced CBF but preserved CBV, representing salvageable tissue (Correct answer)
- Absent CBF and absent CBV, representing infarcted core
- Normal CBF and elevated CBV
- Elevated CBF and reduced MTT
Correct answer: Reduced CBF but preserved CBV, representing salvageable tissue
The penumbra has reduced cerebral blood flow (CBF) but relatively preserved cerebral blood volume (CBV) due to autoregulatory vasodilation, representing at-risk but salvageable brain.
Question 3: Which of the following brain CT findings is most consistent with diffuse axonal injury (DAI) following high-speed trauma?
- Multiple small hemorrhages at the gray-white junction and corpus callosum (Correct answer)
- Large epidural hematoma with midline shift
- Symmetric hypodensity in both MCA territories
- Hyperdense basilar cisterns
Correct answer: Multiple small hemorrhages at the gray-white junction and corpus callosum
DAI results in petechial hemorrhages at gray-white junctions, corpus callosum, and brainstem due to rotational shear forces.
Question 4: On a CT brain, the pineal gland is noted to be shifted 5 mm to the left of midline. This finding most directly suggests:
- A right-sided mass or edema causing midline shift (Correct answer)
- A left-sided mass compressing the right hemisphere
- Normal variant in elderly patients
- Congenital aplasia of the left hemisphere
Correct answer: A right-sided mass or edema causing midline shift
The pineal gland is a reliable midline marker; shift away from the normal position indicates a mass or edema on the contralateral side pushing it.
Question 5: CT angiography (CTA) of the brain is primarily used to evaluate:
- Intracranial aneurysms and vascular malformations (Correct answer)
- Demyelinating lesions
- Cortical atrophy
- Intraparenchymal calcifications
Correct answer: Intracranial aneurysms and vascular malformations
CTA uses rapidly acquired post-contrast images to visualize the cerebral vasculature, detecting aneurysms, AVM, and large-vessel occlusions.
Question 6: A CT brain shows a well-defined, homogeneously hyperdense extra-axial mass that broadly attaches to the inner table of the skull and causes hyperostosis of the adjacent bone. This is most consistent with:
- Meningioma (Correct answer)
- Epidural hematoma
- Lymphoma
- Dural metastasis
Correct answer: Meningioma
Meningiomas are characteristically hyperdense on non-contrast CT, show homogeneous enhancement, have a dural base, and frequently cause adjacent bony hyperostosis.
Question 7: In CT imaging, 'beam hardening artifact' in the posterior fossa is caused by:
- Preferential absorption of low-energy X-ray photons by the dense temporal bones (Correct answer)
- Patient motion during scanning
- Excessive mAs settings
- Metal implants in the cervical spine
Correct answer: Preferential absorption of low-energy X-ray photons by the dense temporal bones
Beam hardening occurs when dense bone absorbs low-energy photons, causing dark streaks between the temporal bones that obscure posterior fossa structures.
Computed Tomography Test Computed Tomography (CT Brain) 4
A CT brain performed for trauma shows a lens-shaped (biconvex) hyperdense collection between the inner table of the skull and the brain.
The most likely source of bleeding is: