Hyperintensity(PVH) lesions and dementia in multiple cerebral infarction. The aspects of cerebral blood flow and metabolism using positron emission tomography.

Many neuropathological investigations have suggested that periventricular hyper-intensity (PVH) lesions on MR-T₂ weighted image reflect ischemic change in these lesions. Intimate relation between PVH and dementia was also reported in some etiological studies. Nevertheless, only a few trial was performed in aspect of cerebral blood flow and metabolism. This study was planned to investigate the relation between PVH. ischemia and dementia using positron emission tomography (PET).<BR>Thirty-three patients with subcortical cerebral infarction were classified under prevalence of PVH on MR-T₂ weighted image. PVH (+) group (n=-17) with severe PVH and PVH (-) group (n=16) without PVH were investigated. Neuropsychological examinations and DSM-III-R were classified them into two stages (none dementia and dementia). In addition, nine normal subjects were examined as control. Regional cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMR02), cerebral blood volume (CBV) were measured by PET using C¹⁵O₂, ¹⁵O₂, ¹¹CO inhalation technique.<BR>None dementia cases in PVH (+) group, significant decrease in CBF and significant increase in OEF were recognized in the region of frontal cingulate gyrus and PVH lesion compared to normal group. Such changes were also significant in compared to PVH (-) group without dementia. Meanwhile, in PVH (+) group with dementia, decrease in CBF coupled with increase in OEF and decrease in CMRO₂ were recognized in PVH lesion and all cortical regions as compared with normal group. In some cortical regions in PVH (+) group with dementia, especially in frontal cortical regions also showed showed such significant changes compared in PVH (-) group with dementia. CBV in the region of frontal cingulate gyrus and CBF/CBV ratio in PVH lesion in PVH (+) group showed significant decrease compared with normal group.<BR>These results indicate the existence of “compensated hypoperfusion” in PVH lesion and cortical regions especially in the region of frontal cingulate gyrus in multiple infarction patients without dementia. Moreover, “ischemic hypoperfusion” was observed in both PVH lesion and cortical regions in multi-infarct dementia. These changes, which seemed to be caused by cerebroateriosclerosis, preceded the appearance of mental deterioration and persisted after dementia appeared. Our findings also showed PVH reflects severe ischemic change of brain in multiple cerebral infarction patient, not only dementia cases but also none dementia patients.