Photochemically-induced cerebral infarction in the rat: comparison of NMR imaging and histologic changes.

The evolution of a photochemically induced cerebral thrombotic infarction was followed in rats during the first week after the insult by means of NMR imaging and histology. Heavily T2-weighted images provided an excellent lesion detection and a high specificity for the discrimination of different histological abnormalities. The T2-weighted images showed a brain lesion evolving during the first 24 h from a homogeneous hyperintense area, histologically corresponding to diffuse vasogenic and cytotoxic oedema with concomitant neuronal necrosis, to an iso-intense area with a hyperintense seam, which microscopically correlated with increased vascular permeability at the periphery of the lesion. The hyperintense seam was observed up to day 7, but at that time coincided with gliomesodermal repair reaction which could be verified histochemically and ultrastructurally. It may be concluded that NMR-micro-imaging at a moderately high field, enables early detection and adequate follow-up of small cerebral infarctions in rats.