DYNAMIC HIGH-RESOLUTION MR-IMAGING OF BRAIN DEOXYGENATION DURING TRANSIENT ANOXIA IN THE ANESTHETIZED RAT

Transient alterations in brain oxygenation during 60-s periods of anox ia were visualized at high spatial resolution (voxel size less-than-or -equal-to 0. 15 mul) with the use of serial long echo time FLASH (fast low-angle shot) magnetic resonance images (measuring time greater-tha n-or-equal-to 6 s) of halothane-anesthetized rats in vivo. Difference images from normoxia and anoxia exploit the signal decrease associated with increased levels of paramagnetic deoxyhemoglobin in the arterial and venous blood pool. Insights into the spatial heterogeneity of oxy gen deprivation are complemented by physiologic information from the t ime course of pertinent signal changes in different regions of the bra in.