Evaluation of CT Functional Imaging in Patients with Cerebral Ischemia

CT functional imaging makes it possible to demonstrate the time course of contrast enhancement as visual images by assigning a shade of gray to each pixel within a scan plane depending on the value of the selected transit parameter at the pixel. In order to assess the clinical usefulness of this method, CT functional images were created from dynamic CT scans of 14 patients with ischemic cerebrovascular diseases who showed negative or equivocal findings on the first conventional CT examination. Diagnostic abilities of CT functional images, especially of the first moment (M1-functional images), were tested by the prospective analysis of clinical course and subsequent CT studies, and were compared with those of conventional and dynamic CT scans.
Conventional CT scans could only suggest the existence of abnormality in one of the 14 cases. Visual inspection of dynamic CT images and analysis of time-density curves were helpful in detecting the abnormal blood flow in 3 of the 14 cases. M1-functional images could reveal the existence and the extent of ischemic lesions responsible for symptoms in 12 of the 14 cases. CT functional imaging was found to be a useful technique for the detection of cerebral ischemia and for the early diagnosis of cerebral infarction.