Analysis Of Cerebral Gray Matter Volume And Perfusion Changes In Subcortical Ischemic Vascular Dementia Patients

Background:Subcortical ischemia vascular dementia (SIVD) is a relatively homogeneous disease and can be further classified into two subtypes of lacunar state and Binswanger disease, both of these entities are related to cerebral small vessel disease.The cause of cognitive impairment in SIVD still remains controversial, has been attributed to the direct effect of subcortical lacunars and white matter lesions (WML), possibly related to the disruption of cortical-subcortical pathways. However, the presence of WML or multiple lacunar infarctions on MRI or CT, representing cerebral small vessel disease, is of limited value for the diagnosis of dementia. More and more investigators have proven that cerebral cortical and subcortical gray matter (GM) atrophy correlated highly with cognitive impairment, rather than any measures of WML or subcortical lacunars. In this study, we aim to investigate and direct compare the distribution profiles of regional cerebral blood flow (CBF) and cerebral GM volume alteration in SIVD patients.Methods:28 SIVD patients and 28 healthy controls were collected in our study and performed brain structural magnetic resonance imaging (MRI) and arterial spin labeling MRI. The MRI data were performed statistical parameter mapping (SPM)-voxel based morphological analysis (VBM) to detect the pattern of GM volume reduction in structure and the distribution of regional CBF alteration in function.Results:Compared to healthy controls, we have found significant reductions of both GM volume and regional CBF in bilateral hippocampus, parahippocampus and anteromedial part of thalamus, as well as anterior cingulate gyrus, insular lobe cortices and orbitofrontal cortices in SIVD patients. Besides, structurally, significant reduction of GM volume was predominantly located at cortices with basic function, including primary motor/sensory cortices and premotor cortices, auditory cortices as well as striate and extra-striate cortices, and left dorsolateral temporal lobe cortices in SIVD patients; functionally, significant hypoperfusion of bilateral prefrontal lobe and temporal lobe cortices was detected in the SIVD group.Conclusion:Our study has found characteristic patterns of both GM atrophy and GM hypoperfusion in mild SIVD patients. Hippocampus, parahippocampus, anteromedial part of thalamus, anterior cingulate gyrus, insular lobe cortices and orbitofrontal cortices are the most affected regions in SIVD patients, indicating that those regions highly related with limbic system are vulnerable to ischemic attack in SIVD patiants. Besides, GM atrophy was predominantly located at coritces with basic function, and those regions may closely relate with disability and motor syptoms of SIVD patients; GM hypoperfusion was found at bilateral prefrontal lobe and temporal lobe, which may play an important role in cognitive impairment of SIVD patients. ASL-MRI technique combined with conventional structural MRI is able to detect early changes of cortical and subcortical GM in SIVD patients without injury.