Chronological Changes in Cerebral Infarction of Photochemical Thrombosis Model: Magnetic Resonance Imaging and Histopathological Correlation

ABSTRACT

OBJECTIVE: Authors investigated magnetic resonance imaging (MRI) and histological characteristics of photothrombotic infraction rat model (PIRM) on long term basis to provide a basis for further research. METHOD: Photothrombotic ischemia was induced in male Sprague-Dawley rats using Rose-bengal dye (20 mg/kg) and cold light. MRI was performed 1, 6, 12, 24 hours, 3, 7 days, 2, 3, 4, 6, and 8 weeks after photothrombosis and obtained T1- & T2-weighted and contrast-enhanced images. Also, T2* images were obtained after superparamagnetic iron oxide injection. After MRI, animals were sacrificed and the brain sections were stained for routine immunohistopathology. RESULTS: MRI and histological analysis revealed well induced lesion in the cortex and showed biological course of infarction. However, PIRM showed rapid development of infarction lacking collateral circulation. Infarction size reached maximum 12 hours after induction, progressively decreasing over 4 weeks. Interstitial and cytotoxic edema were evident at 6, 12, 24 hours, but decreasing afterwards. Neurogenic inflammation appeared on 3rd day and reached maximum on 5~7th day. Arachnoid membrane was characteristically invaded with inflammatory cells and later thickened with fibrosis. CONCLUSION: This study showed PIRM is ideal model to study subacute and chronic stages of cerebral infarction.