Magnetic Resonance Imaging Studies with Cluster Algorithm for Characterization of Brain Edema after Controlled Cortical Impact Injury (CCII)

Abstract

Objective of this study was the characterization of traumatic brain injury induced by a "Controlled Cortical Impact" with magnetic resonance imaging techniques. The impact was applied to the intact dura of the left hemisphere in Sprague-Dawley rats. The pneumatic impactor was accelerated to a velocity of 7m/s contusing the left temporo-parietal hemisphere to a depth of 2mm. Posttraumatic hemispheric swelling and water content were determined gravimetrically. Evans Blue extravasation photometrically, and volume of ischemia by TTC-staining and planimetry. Magnetic resonance imaging was performed by a Bruker biospec 24/40, 90min, 24 and 72h post trauma using a T2w RARE sequence, a T1w sequence, before and after application of contrast agent, and a set of diffusion weighted images for calculation of ADC-maps. Data analysis was performed using a cluster algorithm enabling to interpret corresponding image pairs simultaneously. T2w imaging indicates the maximum edema about 24h post trauma. Bloodbrain barrier damage, detected by T1w imaging, is more predominant in the early posttraumatic phase. The cluster algorithm detects different edema components: from the necrotic core to the perifocal vasogenic rim. MRI in combination with the cluster algorithm will hopefully be a valuable tool in testing neuroprotective agents.