The effectiveness of FID-CT (functional image of dynamic CT) for the evaluation of early cerebral ischemia

A computer program was newly developed to display the ischemic area from the serial dynamic CT scan, namely the functional image of the dynamic CT(FID-CT). The principles of FID-CT are as follows; Seven rapid-sequence dynamic CT scans were taken following a peripheral bolus intravenous injection of 40 ml of iopamidol. As the data from each scan can be separated into three consecutive segments, we obtained 21 images during 44 seconds. Time density curves of each pixel were calculated employing Gamma variate fitting method. Eight functional parameters obtained from this curve were displayed with grayscale pixel by pixel. These eight images were functional images obtained from dynamic CT. Only three or four minutes were required to complete all the calcutations. Twenty-two patients were examined with both FID-CT and 123I-SPECT. In each case, the lesion detected by FID-CT was remarkably consistent with that shown by SPECT. The authors believe that FID-CT is a very useful diagnostic method in the acute stage of cerebral ischemia because the method can be quickly and easily performed and it discloses the ischemic area with fair certainty. (author)