MRI of acute experimental intracerebral hematoma

The purpose of the study was to evaluate the ability of different MR-sequences to detect and delineate experimentally produced hyperacute intracerebral hematomas in rats. Twenty male Sprague-Dawley rats received a unilateral hematoma of various volumes by stereotactic injection of fresh autologous arterial blood into the right caudatoputamen. MRI was performed up to 30 min after-generation of each hematoma. We obtained coronal T2- and T1-weighted spin-echo images. Furthermore we acquired RF-spoiled 2D- and 3D-FLASH images. MR-images were evaluated for signal behavior, location, configuration, size, and volume of each hematoma on a dedicated work station. MR volumetry was correlated to volumetric data obtained from the serial stained histological sections. All hematomas produced signal abnormalities on all sequences in each case. In the majority of cases the hematomas were hypointense. RF-spoiled FLASH 2D- and 3D-sequences showed the best detection of the hematoma owing to their high sensitivity to susceptibility effects. The best correlation between MR- and histological volumetry was found on RF-spoiled FLASH 2D- (corr. 0.81), SE T2- (corr. 0.79), and T1- (corr. 0.74) weighted images. The lowest correlation index was found on the RF-spoiled FLASH 3D-images (corr. 0.51). Signal loss of hematomas on gradient-echo images and--to a lesser extent--spin-echo T2-weighted images due to susceptibility effects can reliably delineate an acute state, whereas conventional MR scans of ischemic stroke may be normal. MRI may thus be the imaging modality of choice in patients with acute brain attack, especially when it is planned to perform diffusion and perfusion MRI before thrombolytic therapy.