Quantification of MRI and MRS characteristics changes in a rat model at different stage of cerebral ischemia

Background: A better understanding the mechanisms of cerebral ischemia is important both for diagnosis and treatment.

Objective: The study aimed to quantify several characteristics of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to indicate the brain tissue changes at different stage of cerebral ischemia in rats.

Methods: In the present study, a rat model of cerebral ischemia was established by middle cerebral artery occlusion (MCAO) in the left hemisphere. MRI and MRS were performed on 15 Sprague Dawley rats 4 H, 24 H, and 1 W after MCAO. Apparent diffusion coefficient (ADC), relative ADC including FNR, PNR, PNF, and metabolite ratio NCC were proposed to reflect the changes of water diffusion and metabolism in brain tissue.

Results: ADCs of focal zone and penumbra zone from 1 W group were significantly larger than those from 4H group, respectively (both p < 0.05). PNR and PNF of 24H and 1 W groups were significantly less than 4H group (all p < 0.01). NCCs of focal zone and penumbra zone were significantly less than the normal zone within 4H, 24H, and 1 W groups, respectively (both p < 0.01). While NCCs of penumbra zone from 24H and 1 W groups were significantly larger than 4H group (both p < 0.01).

Conclusion: We conclude that combination of MRI and MRS characteristics can provide significant indicators for ischemic damage at different stage of cerebral ischemia in a rat model.