Test on Neuroimaging of Intracranial Hematomas

Question 1: On axial CT, acute subdural hematomas appear as crescent-shaped extra-axial collections of high attenuation.

A. Ano

B. Ne

Explanation: Acute subdural hematomas are described as appearing as crescent-shaped extra-axial collections of high attenuation on axial CT scans.

Question 2: Subdural hematomas are rarely associated with acute deceleration injuries, such as those sustained from motor vehicle accidents or falls.

A. Ano

B. Ne

Explanation: Patients with a subdural hematoma commonly present after acute deceleration injury from a motor vehicle accident or fall. The same mechanism can also cause cortical contusions and DAI, which are frequently seen in association with acute subdural hematomas.

Question 3: Which of the following statements accurately describes the typical changes in CT density for a subdural hematoma over time, as described in the study materials?

A. Acute subdural hematomas are initially hypodense, becoming hyperdense within hours, and then progressively decreasing in density.

B. The density of an acute subdural hematoma initially increases due to clot retraction, then progressively decreases as protein degradation occurs.

C. Chronic subdural hematomas typically have high attenuation values, similar to normal brain tissue.

D. Subdural hematomas always appear hyperdense on CT, regardless of their age.

Explanation: The study materials state that 'The CT appearance of subdural hematomas changes with time. The density of an acute subdural hematoma initially increases because of clot retraction.' It then adds, 'The density will then progressively decrease as protein degradation occurs within the hematoma.' Chronic subdural hematomas are described as having 'low attenuation values similar to CSF,' not high attenuation. While acute subdural hematomas are typically hyperdense when imaged, their initial density change is an increase, and they do not always appear hyperdense, especially in cases of severe anemia or as they age into the chronic phase.

Question 4: Which of the following describes the typical appearance of chronic subdural hematomas on noncontrast CT scans?

A. They appear as crescent-shaped extra-axial collections of high attenuation.

B. They demonstrate low attenuation values, similar to CSF.

C. They frequently have a lentiform or biconvex appearance.

D. They are hyperdense, measuring 50 to 60 HU, relative to normal brain.

Explanation: Chronic subdural hematomas have low attenuation values similar to CSF on noncontrast CT scans. Crescent-shaped extra-axial collections of high attenuation describe acute subdural hematomas on axial CT. A lentiform or biconvex appearance is described for subacute subdural hematomas on coronal MR or for epidural hematomas. Hyperdense measurements of 50 to 60 HU are characteristic of acute subdural hematomas.

Question 5: Peripheral enhancement of the collection on postcontrast CT is a specific indirect sign used to diagnose an isodense phase subdural hematoma.

A. Ano

B. Ne

Explanation: The study materials state that postcontrast imaging is generally not required for evaluation of a subdural hematoma, and peripheral enhancement was noted in a case of subacute injury, not listed as one of the indirect signs for diagnosing an isodense phase subdural hematoma.