EVALUATION OF ACUTE BRAIN EDEMA USING QUANTITATIVE MAGNETIC-RESONANCE-IMAGING - EFFECTS OF PRETREATMENT WITH DEXAMETHASONE

We developed a quantitative magnetic resonance imaging method to permit a rapid assessment of brain water content during osmotic brain edema produced by intraperitoneal (ip) injection of distilled water. Fifteen minutes after water injection, the normalized mean image intensity (MIn) from a spin‐echo pulse sequence (TE = 80 ms, TR = 1085 ms) was the same as that measured from control animals not injected with water. Sixty minutes after the water injection, the mean ± SEM brain image MIn had increased by 10.8 ± 2.4% compared to 3.4 ± 0.7% in control animals (P < 0.05). Blood plasma osmolality decreased by 6–10% during this time interval. A subsequent ip injection of hypertonic NaCl solution (100 gm/liter) caused the blood plasma osmolality and brain image MIn to return toward their initial values. MIn of cerebral gray matter correlated with tissue water content measured in parallel studies. Animals pretreated with 0.25 mg/(kg day) dexamethasone had cerebral gray matter MIn values during osmotic edema which were lower than those of untreated animals. © 1992 Academic Press, Inc. Copyright © 1992 Wiley‐Liss, Inc., A Wiley Company