MRI of acute experimental intracerebral hematoma

The purpose of the study was to evaluate the ability of different MR-sequen ces to detect and delineate experimentally produced hyperacute intracerebra l hematomas in rats. Twenty male Sprague-Dawley rats received a unilateral hematoma of various volumes by stereotactic injection of fresh autologous a rterial blood into the right caudatoputamen. MRI was performed up to 30 min after generation of each hematoma. We obtained coronal T2- and TI-weighted spin-echo images. Furthermore we acquired RF-spoiled 2D- and 3D-FLASH imag es. 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 histolo gical sections. All hematomas produced signal abnormalities on all sequence s 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 hemato ma owing to their high sensitivity to susceptibility effects. The best corr elation between MR- and histological volumetry was found on RF-spoiled FLAS H 20- (corr. 0.81), SE T2- (corr. 0.79) and T1- (corr. 0.74) weighted image s. The lowest correlation index was found on the RF-spoiled FLASH 3D-images (corr. 0.57). 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 isc hemic 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 perfo rm diffusion and perfusion MRI before thrombolytic therapy.