Calculation of absolute cerebral blood volume and of cerebral blood flow by means of electron beam computed tomography in acute ischemia

The utility of electron beam computed tomography (EBT) to estimate cerebral blood Volume (CBV) and cerebral blood flow (CBF) was evaluated. Eleven patients with suspected acute cerebral ischemia were investigated. The EBT was performed with an acquisition time of 50 ms per slice at eight parallel levels. To compare signal/noise and contrast/noise ratios the data from the EBT investigation were compared to a similar examination on a spiral CT. The signal/noise ratio with EBT was about 30%, the contrast/noise ratio 25% of that with spiral CT. The absolute Values of CBV were 4.9+/-1.2 ml/100 g (EBT); CBF was 50.5+/-7.0 ml/100 g/min in normal contralateral brain tissue. In four patients with proven infarcts on follow-up,the ischemic areas had a CBV ranging from 1.7 to 3.8 ml/100 g,while CBF ranged from 9.4 to 24.5 ml/100 g/min. Using a bolus injection of contrast material, calculation of absolute CBV and CBF is feasible using EBT. Advantages of EBT are the absolute measurements possible and it's multislice capability. Disadvantages, however, are caused by the high image noise,limiting the demarcation of ischemic tissue.