Magnetic resonance imaging assessment of cerebral hemodynamics during XXXX in @entity35 .

@entity308 @entity1541 @entity18906 @entity35 @entity4337
High-speed magnetic resonance imaging was used to perform simultaneous measurements of relative cerebral blood volume (rCBV) and water diffusion changes during @entity308 ( @entity308 ) induced by cortical @entity4337 application. @entity35 were fitted epidurally with a rubber chamber. @entity4337 was perfused through the chamber until @entity308 was indicated by a negative direct current (DC) potential shift. Magnetic resonance imaging scans used echo planar diffusion and @entity18906 -weighted images. Iron dextran was injected as a blood pool contrast agent to make subsequent changes in @entity18906 (or @entity18906 ) directly proportional to changes in CBV. Multislice maps of @entity1541 ( @entity1541 ) and rCBV were generated with 6- to 16-second time resolution, which revealed transient @entity1541 and rCBV changes propagating over the cortex after @entity4337 application. Transient @entity1541 declines appeared simultaneously with the DC shift, whereas rCBV increase followed with a delay of 16.4+/-14.9 seconds. Prolonged rCBV decrease was observed after the initial increase during the @entity308 in half of the animals. The delayed rCBV response after the @entity1541 change supports the observation of increased energy demand because of repolarization. Simultaneous DC potential recording and @entity1541 measurements in corresponding sites of the cortex indicate that transient @entity1541 decreases during @entity308 reflect water shifts associated with cell depolarization.
