P-31 AND H-1 SPECTROSCOPIC IMAGING STUDIES OF FOCAL ISCHEMIA IN RAT-BRAIN

P-31, H-1 and lactate spectroscopic imaging were used to study the eff ect of middle cerebral artery occlusion in spontaneously hypertensive rats. This study included both permanent (6 h ischemia) and transient (3 h ischemia with 12 h reperfusion) occlusion. P-31 localized spectra acquired from a 87.5 mu l volume in 1 hour 50 min detected changes in pH and high energy phosphate levels. Water-suppressed H-1 spectra acq uired from a 48 mu l volumes in 50 min showed changes in N-acetyl aspa rtate (NAA) and total creatine levels. A lactate editing sequence was used to acquire spectra from a 22 mu l volumes in 50 min. Permanent is chemia resulted in very low pH (6.5), elevated inorganic phosphate and lactate levels and decreased high energy phosphate and NAA levels. Re perfusion following 3 h of ischemia showed pH recovery to normal value s (7.15), however the lactate level remained high throughout the entir e reperfusion period High energy phosphates and NAA deteriorated furth er. The spectroscopic information correlated well with high resolution proton images and histopathology.