PERFUSION DEFICIT PARALLELS EXACERBATION OF CEREBRAL ISCHEMIA REPERFUSION INJURY IN HYPERGLYCEMIC RATS/

Magnetic resonance imaging (MRI) techniques were used to determine the effect of preexisting hyperglycemia on the extent of cerebral ischemi a/reperfusion injury and the level of cerebral perfusion. Middle cereb ral artery occlusion (MCAO) was induced by a suture insertion techniqu e. Forty one rats were divided into hyperglycemic and normoglycemic gr oups with either 4 hours of continuous MCAO or 2 hours of MCAO followe d by 2 hours of reperfusion. Diffusion-weighted imaging (DWI) was perf ormed at 4 hours after MCAO to quantify the degree of injury in 6 brai n regions. Relative cerebral blood flow (CBF) and cerebral blood volum e (CBV) were estimated using gradient echo (GE) bolus tracking and ste ady-state spin echo (SE) imaging techniques, respectively. Brain injur y correlated with the perfusion level measured in both SE CBV and dyna mic GE CBF images. In the temporary MCAO model, mean lesion size in DW I was 118% larger and hemispheric CBV was reduced by 37% in hyperglyce mic compared with normoglycemic rats. Hyperglycemia did not significan tly exacerbate brain injury or CBV deficit in permanent MCAO models. W e conclude that preexisting hyperglycemia increases acute postischemic MRI-measurable brain cellular injury in proportion to an associated i ncreased microvascular ischemia.