Reperfusion in a gerbil model of forebrain ischemia using serial magnetic resonance FAIR perfusion imaging

Background and Purpose-Existing methods for the quantitative measurement of the changing cerebral blood flow (CBF) during reperfusion suffer from poor spatial or temporal resolution. The aim of this study was to implement a r ecently developed MRI technique for quantitative perfusion imaging in a ger bil model of reperfusion. Flow-sensitive alternating inversion recovery (FA IR) is a noninvasive procedure that uses blood water as an endogenous trace r. Methods-Bilateral forebrain ischemia of 4 minutes' duration was induced in gerbils (n=8). A modified version of FAIR with improved time efficiency was used to provide CBF maps with a time resolution of 2.8 minutes after recir culation had been initiated. Quantitative diffusion imaging was also perfor med at intervals during the reperfusion period. Results-On initiating recirculation after the transient period of ischemia, the FAIR measurements demonstrated either a symmetrical, bilateral pattern of flow impairment (n=4) or an immediate side-to-side difference that beca me apparent with respect to the cerebral hemispheres in the imaged slice (n =4), The flow in each hemisphere displayed a pattern of recovery close to t he preocclusion level or, alternatively, returned to a lower level before d isplaying a delayed hypoperfusion and a subsequent slow recovery, The diffu sion measurements during this latter response suggested the development of cell swelling during the reperfusion phase in the striatum, Conclusions-The CBF during the reperfusion period was monitored with a high time resolution, noninvasive method, This study demonstrates the utility o f MRI techniques in following bloodflow changes and their pathophysiologica l consequences.