Question 1: Which of the following is NOT true concerning epidural hematoma?

Epidural hematoma is caused by the laceration of a dural artery or venous sinus by a fracture.
The hematoma may cross suture lines.
On CT, the hematoma forms a hyperdense, biconvex mass.
On CT, the hematoma may contain hyperdense foci due to active bleeding.
The hematoma may cross dural reflections.

Explanation: An epidural hematoma occurs when an artery ruptures and blood collects between the dura and the skull. At suture lines, the dura tightly adheres to the calvarium. Since an epidural hematoma does not cross these tight junctions occur, it is not seen crossing suture lines.

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Question 2: Which of the following is NOT true concerning cerebral contusion?

Cerebral contusion often occurs when the brain impacts an osseous ridge or dural fold.
On CT, cerebral contusions appear as ill-defined hypodense areas.
On CT, cerebral contusions are often mixed with foci of hemorrhage.
After 1 to 2 days, coalescence of petechial hemorrhages into a rounded hematoma is common.
The occipital, temporal, and parietal lobes are the most common locations of cerebral contusion.

Explanation: Cerebral contusions most commonly occur in the anterior tip, the inferior surface and sylvian region of the temporal lobe, the anterior pole and inferior surface of the frontal lobe, the dorsolateral midbrain, and the inferior cerebellum.

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Question 3: Which of the following is NOT true concerning diffuse axonal injury?

Diffuse axonal injury can present with a normal head CT.
Diffuse axonal injury is the most common cause of morbidity in CNS trauma.
Diffuse axonal injury is often associated with intraventricular hemorrhage.
On CT, diffuse axonal injury appears as ill-defined areas of high density or hemorrhage.
Acceleration, deceleration, and rotational forces cause diffuse axonal injury.

Explanation: On CT, diffuse axonal injury occurs as ill-defined areas of low density. The often accompanying hemorrhage appears as bright spots of high density. The hemorrhage is found within the brain parenchyma, not in the ventricular system.

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Question 4: Given the following CT, the most likely diagnosis is:

Diffuse axonal injury.
Subarachnoid hemorrhage over cerebral convexities.
Subdural hematoma.
Hypertensive hemorrhage in the occipital lobe.

Explanation: The arrowheads in the image indicate the areas of high density that correspond to hemorrhage over cerebral convexities.

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Question 5: The CT on the left, taken prior to contrast administration and the CT on the right, taken after contrast administration, show:

Epidural hematoma.
Subarachnoid hemorrhage.
Glioblastoma multiforme.
Subdural empyema.

Explanation: The subdural empyema in the right frontal lobe is outlined by arrowheads in the images above. Notice the enhancement of the edges upon contrast administration (right image).

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Question 6: Given the following head CT, the most likely diagnosis is:

Acute subdural hematoma.
Epidural hematoma.
Chronic subdural hematoma.
Subarachnoid hemorrhage.

Explanation: The arrowheads outline the high-density, crescent-shaped hematoma overlying the right cerebral hemisphere. Note the hypodense region (arrow) within the high-density hematoma (arrowheads), which may indicate active bleeding. The high density and active bleeding are indicative of an acute subdural hematoma.

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Question 7: Given the following head CT, the most likely diagnosis is:

Hypertensive hemorrhage in the frontal lobe.
Subarachnoid hemorrhage over cerebral convexities.
Diffuse axonal injury.
Intracranial tumors.

Explanation: The arrows indicate the hemorrhage in the subcortical white matter of the left frontal lobe. Such hemorrhage often accompanies diffuse axonal injury, the direct evidence of which (ill-defined areas of low density) is not always apparent on CT. (see question 3)

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Question 8: Which of the following is NOT shown in this CT?

Intraventricular hemorrhage.
Subarachnoid hemorrhage.
Diffuse hypodensity.
Diffuse axonal injury.

Explanation: The intraventricular hemorrhage is clearly visible as the high density blood in the left lateral ventricle. The area of high density in the left cerebral hemisphere is the location of the subarachnoid hemorrhage (arrow). Areas of low density around the subarachnoid hemorrhage are diffuse hypodensity as a result of edema (arrowheads).

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Question 9: Which of the following is NOT an advantage to performing a CT scan for stroke?

CT can be rapidly performed.
It is always possible to distinguish between old and new infarcts.
CT allows easy exclusion of hemorrhage.
CT allows the assessment of prenchymal damage.

Explanation: It is not always easy to distinguish between old and new infarcts. MR is a better in this regard. Other disadvantages of CT are its current lack of functional information and limited ability to evaluate the vertebrobasilar system.

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Question 10: Which of the following is NOT true concerning CT?

CT is the imaging modality of choice for the detecting subarachnoid hemorrhage.
Small subarachnoid bleeds may be inapparent.
On CT, subarachnoid hemorrhage appears as high density within sulci and CSF cisterns.
CT becomes more sensitive days to weeks after the acute phase of a subarachnoid hemorrhage.

Explanation: Blood is reabsorbed from CSF days to weeks after the acute phase of a subarachnoid hemorrhage. As this occurs, the hemorrhage becomes isodense to the brain. Thus, CT becomes less sensitive in detecting subarchnoid hemorrhage.

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