Differentiation of gray matter and white matter perfusion in patients withunilateral internal carotid artery occlusion

In this study, we investigated differences between gray matter and white ma tter perfusion in patients with a unilateral occlusion of the internal caro tid artery (ICA) with dynamic susceptibility contrast. Seventeen patients a nd 17 control subjects were studied, using T2*-weighted gradient echo acqui sition. Gray and white matter regions were obtained by segmentation of inve rsion recovery MRI. Lesions were excluded by segmentation of T2-weighted MR I. In the symptomatic hemisphere, cerebral blood volume was increased in wh ite matter (P <.05) but not in gray matter. No cerebral blood now changes w ere found. All timing parameters (mean transit time [MTT], time of appearan ce, and time to peak) showed a significant delay for both white and gray ma tter (P <.05), but the MTT increase of white matter was significantly large r than for gray matter (P <.05). These findings indicate that differentiati on between gray and white matter is essential to determine the hemodynamic effects of an ICA occlusion.