Gray matter and white matter perfusion imaging in patients with severe carotid artery lesions

PURPOSE: To determine, with dynamic susceptibility contrast-enhanced magnetic resonance (MR) imaging, changes in gray matter and while matter perfusion in patients with internal carotid artery (ICA) occlusions. MATERIALS AND METHODS: Regional cerebral blood volume (CBV), mean transit time, arrival time (time for contrast material to arrive in the brain), and peak time,(time to highest contrast material concentration in the brain) were determined in 44 patients and 33 control subjects. Patients were divided into three groups: patients with a unilateral ICA occlusion, patients with a unilateral ICA occlusion and a contralateral severe stenosis (> 70%), and patients with bilateral ICA occlusions. RESULTS: Compared with control subjects, patients with unilateral ICA occlusions had hemodynamic changes in the ipsilateral hemisphere: Mean transit time, arrival time, and peak time were increased in white and gray matter (P < .001), and regional CBV was significantly increased in white matter only (P < .01). Hemodynamic changes were more pronounced in patients with bilateral ICA occlusions: Compared with control subjects, mean transit time, arrival time, peak time, and regional CBV were increased in both white and gray matter in both hemispheres (P < .001). CONCLUSION: Dynamic susceptibility contrast-enhanced MR imaging can enable measurement of relative hemodynamic changes in patients with ICA occlusions, with the advantage that gray and white matter perfusion can be distinguished.