T1 AND T2 WEIGHTED MAGNETIC-RESONANCE-IMAGING OF EXCITOTOXIN LESIONS AND NEURAL TRANSPLANTS IN RAT-BRAIN INVIVO

On T1- and T2-weighted magnetic resonance (MR) images obtained at 0.14 T the rat brain was visible in the rat head as an area of relative high signal intensity. The enlarged lateral ventricles produced by intrastriatal injections of the excitotoxin kainic acid (KA) were clearly visible as areas of low signal intensity in T1-weighted images but could not be differentiated from normal brain tissue on T2-weighted images for the protocols utilized. Repeated T1-weighted MR images of individual rats demonstrated a progression in the extent of the lesions over an approximately 14-week period following the injection of KA. On the T2-weighted images, areas of relatively high signal intensity corresponding to tissue on the lesioned side of the brain were evident. As the lesion progressed and the remaining tissue visible on the T1-weighted images decreased, the region of high signal intensity visible on the T2-weighted images diminished. This area of high signal intensity on the T2-weighted images appeared to correspond to tissue undergoing a neurodegenerative process. MR images from continguous slices of brain demonstrated the extent of the KA-induced degeneration throughout the brain, although volume averaging of multiple brain structures was a possible confounding factor. Features apparently corresponding to fetal striatal tissue transplants growing within the enlarged lateral ventricle were visible on T1-weighted images but could not be discriminated on the T2-weighted images. MR imaging is useful for monitoring in vivo the anatomical location and progression of excitotoxin lesions and the location of fetal striatal tissue transplants in lesioned rat brain. © 1990.