Differentiation of gray matter and white matter perfusion in patients with unilateral internal carotid artery occlusion.

In this study, we investigated differences between gray matter and white matter perfusion in patients with a unilateral occlusion of the internal carotid artery (ICA) with dynamic susceptibility contrast. Seventeen patients and 17 control subjects were studied, using T2*-weighted gradient echo acquisition. Gray and white matter regions were obtained by segmentation of inversion recovery MRI. Lesions were excluded by segmentation of T2-weighted MRI. In the symptomatic hemisphere, cerebral blood volume was increased in white matter (P < .05) but not in gray matter. No cerebral blood flow changes were found. All timing parameters (mean transit time [MTT], time of appearance, and time to peak) showed a significant delay for both white and gray matter (P < .05), but the MTT increase of white matter was significantly larger than for gray matter (P < .05). These findings indicate that differentiation between gray and white matter is essential to determine the hemodynamic effects of an ICA occlusion.