White matter hyperintensities may correspond to areas of increased blood volume: correlative MR and PET observations

A method for correlating positron emission tomography with magnetic resonance (MR) imaging enabled the authors to examine the high intensity white matter areas in T2-weighted images in patients with internal carotid artery occlusion. The high intensity areas showed increased cerebral blood volume compared with the ipsilateral and contralateral normal intensity white matter. This observation may have relevance in explaining some of the patchy white matter lesions seen in MR images.