Hypothermia reduces cytotoxic edema and metabolic alterations during the acute phase of massive SAH: a diffusion-weighted imaging and spectroscopy study in rats.

ABSTRACT Acute changes in cerebral perfusion and metabolism after subarachnoid hemorrhage (SAH) have been shown to contribute significantly to acute brain injury. The purpose of this study was to examine the effects of moderate hypothermia on the acute changes after massive experimental SAH as evaluated by diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS). SAH in rats was induced by injection of 0.5 mL of arterial blood. Normothermic animals (NT, n = 10) were kept at 37.0 ± 0.2°C, while temperature was lowered to 32.0 ± 0.2°C in the primary hypothermia group (pHT, n = 10) prior to SAH and in the secondary hypothermia group (sHT, n = 10) immediately after SAH. DWI and MRS were performed from 30 min prior up to 3 h after injury. The apparent diffusion coefficient (ADC) was measured in cortical and hippocampal regions of interest (ROIs). MRS included lactate, N-acetyl aspartate (NAA), and creatine in a central voxel. DWI showed a generalized, significant decline in ADC after SAH in N...