ASSESSMENT OF CEREBRAL BLOOD-VOLUME WITH DYNAMIC SUSCEPTIBILITY CONTRAST-ENHANCED GRADIENT-ECHO IMAGING

Objective: Dynamic susceptibility contrast (DSC) enhanced MRI was used to study relative cerebral blood volume (rCBV). Materials and Methods : We examined 15 healthy subjects and 47 patients with vascular stenos is or occlusion, with brain infarctions, and with cerebral neoplasms. During bolus injection of Gd-diethylenetriamine pentaacetic acid, a se ries of rapid T2-weighted fast low angle shot two-dimensional images were recorded from the same slice. From these images, changes in signa l intensity during bolus passage were computed pixel-by-pixel and conv erted into contrast agent concentration curves. Applying the principle s of indicator dilution theory, images of rCBV were calculated. Result s and Conclusion: Regions of infarctions show almost zero rCBV. In pat ients with high-grade vascular stenosis or occlusion a bolus delay in comparison to the unaffected side and an increased mean transit time c an be observed. Some of the affected areas show an increased rCBV, whi ch is a well-known physiological mechanism that takes place to compens ate for the reduced cerebral blood pressure. In brain tumors, rCBV ima ging reveals focal or homogeneous areas of increased blood volume. Thi s can even be observed in low-grade astrocytomas with unaffected blood -brain barrier. In CBV imaging, the effects of radiotherapy on tumor t issue can be monitored as a significant decrease of rCBV in tumor tiss ue after therapy.