Cytotoxic brain edema: assessment with diffusion-weighted MR imaging.

Abstract

To determine whether cytotoxic brain edema is associated with a decrease in diffusion, it was induced in rats, in the absence of ischemia, with an established model of acute hyponatremic encephalopathy. Cytotoxic brain edema secondary to acute hyponatremia was induced with intraperitoneal injections of 2.5% dextrose in water and subcutaneous injection of arginine-vasopressin. Coronal spin-echo magnetic resonance (MR) images were obtained with and without strong diffusion-sensitizing gradients before and after induction of acute hyponatremia. The apparent diffusion coefficient (ADC) was measured at two coronal section locations. In hyponatremic rats, the brain ADC was significantly reduced (P = .0153 and .0001) and was positively correlated with increased total brain water content (P = .0011). Plots of ADC versus total brain water showed a statistically significant inverse linear relationship between ADC and increasing brain water at the anterior coronal section location. The results indicate that the ADC may be a sensitive indicator of cytotoxic brain edema and thus may enable quantitative evaluation of such edema with diffusion-weighted MR imaging.

Hypoxic and ischemic hypoxia exacerbate brain injury associated with metabolic encephalopathy in laboratory animals.

“…Microdialysis application of N-methyl-D-aspartate or glutamate to rat brain has been shown to result in a decrease of the ADC, concomitant with a shift of water from extracellular to intracellular space (32). It has been suggested (17,19,44) Hepes-Tris, 5; pH 7.40. Uptake media contains (in mM) choline chloride, 140; MgCI2, 5; EGTA, 0.2; NaCI, 1; tetrodotoxin, 0-3; Hepes-Tris, 5; pH 7.40.…”

“…A net restriction of water proton movement, due to an increased proportion of confined intracellular fluid, and thus the location of cytotoxic brain edema, was determined using diffusion-weighted MRI experiments as previously described ( 19,20). The ADC has been proposed to be a marker ofcytotoxic edema, as it decreases progressively as water shifts from the extracellular to intracellular space ( 19,20).…”

“…The ADC has been proposed to be a marker ofcytotoxic edema, as it decreases progressively as water shifts from the extracellular to intracellular space ( 19,20). Spatial "maps" of the ADC (Fig.…”

“…1 B) (20,22) and diffusionweighted images (Fig. 1 A) (19,20), and from the corresponding areas of the contralateral hemisphere in each individual animal. Synaptosomes were extracted from the cerebral cortex of normal, hyponatremic normoxic, normonatremic ischemic, and hyponatremic ischemic cat brain.…”

Chronic Subdural Hematoma With Vasogenic Edema in the Cerebral Hemisphere. Case Report.

“…3,4,9) We describe a case of chronic subdural hematoma associated with vasogenic edema in the ipsilateral cerebral hemisphere identified by diffusion-weighted imaging and measurements of apparent diffusion coefficient (ADC) in the cerebral hemispheres.…”