An early CT sign of ischemic infarction: increased density in a cerebral artery.

The diagnosis of ischemic cerebral infarction by CT usually is not possible for 12-24 hr after the event. A sign that allows earlier diagnosis is increased density of a cerebral vessel secondary to a thrombus or embolus. We report 19 cases of increased density in a middle cerebral artery or one of its major branches visible on the initial CT scan of patients subsequently clinically proven to have suffered a cerebrovascular accident. In three cases angiography confirmed the presence of embolus or thrombus as seen on the CT scans. In several cases subsequent CT scans showed the density to dissipate, thereby confirming its nature as thrombus or embolus. Recognition of this finding will allow earlier diagnosis of ischemic infarction, which may be important in instituting an appropriate therapeutic regimen.

A protocol for the use of contrast enhancement in cranial computed tomography.

There is some confusion regarding the indications for and methodology of the use of contrast material in cranial computed tomography. Some authors recommend a nonenhanced scan in all cases, followed by an enhanced scan if indicated by the symptoms or the appearance of the unenhanced scan. Others have questioned the value of the nonenhanced scan in patients with tumor. The authors offer a protocol for the use of contrast material. Possible tumor patients are scanned with contrast material alone; other patients are scanned either (a) without contrast material or (b) both with and without contrast material, depending upon the most likely clinical diagnosis.

Leukemic infiltration of the optic nerves: demonstration by computerized tomography.

Enlargement of the optic nerves by leukemic infiltration has been demonstrated by computerized tomography (CT) in two cases. A follow-up CT scan shows reduction in size of the optic nerve after central nervous system radiation in one case. The pathophysiology of central nervous system leukemia is discussed.