title: Quantitative analysis of hemodynamic and metabolic changes in subcortical vascular dementia using simultaneous near-infrared spectroscopy and fMRI measurements.
abstract: Subcortical vascular dementia (SVD) is a form of vascular dementia from small vessel disease with white matter lesions and lacunes. We hypothesized that hemodynamic and metabolic changes in the cortex during a simple motor task may reflect the impaired neurovascular coupling in SVD. We used fMRI and near-infrared spectroscopy (NIRS) simultaneously, which together provided multiple hemodynamic responses as well as a robust estimation of the cerebral metabolic rate of oxygen (CMRO(2)). During the task periods, the oxy-hemoglobin, total-hemoglobin, blood oxygenation level-dependent (BOLD) response, cerebral blood flow (CBF), and CMRO(2) decreased statistically significantly in the primary motor and somatosensory cortices of SVD patients, whereas the oxygen extraction fraction increased when compared with controls. Notably, the flow-metabolism coupling ratio, n representing the ratio of oxygen supply to its utilization, showed a robust reduction in the SVD patient group (n(Control)=1.99 ± 0.23; n(SVD)=1.08 ± 0.24), which implies a loss of metabolic reserve. These results support the pathological small vessel compromise, including an increased vessel stiffness, impaired vascular reactivity, and impaired neurovascular coupling in SVD. In conclusion, simultaneous measurement by NIRS and fMRI can reveal various hemodynamic and metabolic changes and may be used for as an early detection or monitoring of SVD.
authors.affiliation: Department of Bio and Brain Engineering, KAIST, Daejeon, Republic of Korea.
authors.forename: Sungho
authors.initials: S
authors.lastname: Tak
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Yoon
authors.forename: Jaeduck
authors.initials: J
authors.lastname: Jang
authors.forename: Kwangsun
authors.initials: K
authors.lastname: Yoo
authors.forename: Yong
authors.initials: Y
authors.lastname: Jeong
authors.forename: Jong Chul
authors.initials: JC
authors.lastname: Ye
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001931:Brain Mapping / Q000379:methods*; D002560:Cerebrovascular Circulation; D015140:Dementia, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D010100:Oxygen