Appraisal of the angiographic circulation time as an index of cerebral blood flow

The relationship of the brain angiographic mode circulation time (AVCT) to the mean transit time of the vascular indicator C¹⁵ O labeled hemoglobin (t) and the regional cerebral flood flow (rCBF), as measured by the clearance of the diffusible tracer H₂¹⁵O, was examined in 38 patients with selected cerebral diseases. The results demonstrate that a predictable relationship does exist between the rCBF and t. This relationship is linear when plotted as t versus 1/CBF. Further, t can be estimated with sufficient accuracy from the AVCT to permit at least a qualitative assessment of rCBF from the cerebral angiogram.