The peak time difference of time-density curve in intravenous digital subtraction angiography correlates to an asymmetric cerebral blood flow as determined by positron emission tomography

A time-density curve study in contrast media transit is theoretically possible to evaluate an asymmetric cerebral perfusion. In this study, we confirmed the correlation between the peak time difference in a regional time-density curve and the asymmetry of cerebral blood flow using positron emission tomography (PET). Five patients with a unilateral occlusion of the carotid or middle cerebral artery underwent intravenous digital subtraction angiography and PET on two successive days. We placed four pairs of regions of interest as appropriate in each study, and obtained the peak time of a regional time-density curve, regional cerebral vascular blood flow (rCVBF) and regional cerebral blood flow (rCBF). We obtained a significant linear correlation between the right-to-left difference of peak time and the difference of 1/rCVBF (r = 0.85, p < 0.001). The peak time difference also showed good correlation to the absolute difference of rCBF (r = -0.84, p < 0.001). A time-density curve study can detect the asymmetry of rCBF, and may be used to evaluate unilateral ischemic damages.