BRAIN CIRCULATION STUDIES BY EXTERNAL COUNTING OF INTRAVENOUSLY INJECTED RISA; A PRELIMINARY REPORT.

Abstract

A method of determination of intracranial circulation by external counting of radioisotope following injection of RISA into the cubital vein was described. Although this procedure was not completed in its methodology, its simplicity as well as its sensitivity for detecting hemodynamic changes were considered to be of much benefit for clinical use. As the parameters for cerebral circulation, transit time (TT), which was considered equal to brain circulation time, rate of degree of ascending slope to height of the plateau (Tan A)/P, arm brain circulation time (ABCT), cranial blood volume (CBV) and cranial blood flow (CBF) were obtained in each hemisphere.(1) Mean values and their distributions (1.96σ) of each parameter for cerebral circulation obtained in 13 control cases were as follows : TT of 9.0±2.1sec. in the left and 8.7±2.8sec. in the right hemisphere, Tan A/P of 1.06±0.37, ABCT of 14.4±4.2sec., CBV of 235±85ml., and CBF of 1, 600±580ml./min.(2) In 22 cases with cerebral hemorrhge and cerebral infarction, one or more of the following abnormalities were observed in 16 cases : a prolongation of TT and/or of ABCT and decrease in Tan A and/or in CBF, however, CBV remained within normal limits except in I case associated with polycythemia vera in which it was significantly increased. Cerebral angiography demonstrated a complete occlusion of left middle cerebral artery and a marked narrowing of left internal carotid artery in 2 cases with a significant decrease in CBF on the affected side.(3) An increase in CBF and CBV was noted on the affected side in 2 cases with subarachnoid hemorrhage due to A-V malformation.(4) Several factors involved in possible sources of error in this procedure and requirements for further study were discussed.