Small animal magnetic resonance imaging: a means of studying the development of structural pathologies in the rat brain.

Small animal magnetic resonance imaging (SAMRI) was developed to detect structural tissue changes associated with disease states in animal models. The disease state of particular interest here is that associated with long-term alcohol abuse. The small animal model used for this study was the thiamine-deficient Sprague-Dawley rat, a model that provides a relatively rapid means of mimicking the ventriculomegaly frequently found in human chronic alcohol abusers. A custom-designed coil tuned to the magnetic field of a 1.5 Tesla clinical magnetic resonance imager provided the technology necessary to delineate discreet regions of the rat brain with clarity. Adult, male rats were imaged, placed on a thiamine-deficient pellet diet for approximately 6 weeks, and then reimaged. Treatment associated enlargement of the lateral ventricles identified in the images was verified by posttreatment histological analysis of the brains of these rats. The results demonstrated that SAMRI is capable of providing dramatic and reliable visual evidence of pathological structural changes in small tissue volumes with high resolution and reproducibility. Furthermore, the noninvasiveness of SAMRI allowed for imaging of the same animals over time, thereby reducing the numbers of animals needed for convincing documentation of the changes in ventricular size.