Ai-Ling Lin1, Hanzhang Lu2, Peter T. Fox1, Timothy Q. Duong1
1Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; 2Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States
The purpose of the study was to compare the VAcular Space Occupancy (VASO) techniques and a contrast agent-based (Gd-DTPA) method in determining CBV changes during multi-frequency visual stimulation (4 and 8 Hz). Specifically, we aimed to indentify the impact of repetition time (TR) on CBV changes determination using VASO. With additional measurements in cerebral blood flow (CBF), the flow-volume coupling relationship (\ value) and cerebral metabolic rate of oxygen (CMRO2) were further determined. The results showed that with short TR (2s), the CBV changes determined by VASO were overestimated and thus caused the underestimated of CMRO2 changes with a fMRI biophysical model. With Long TR (6s), CBV changes determined by VASO were consistent with those obtained with the Gd-DTPA method. In addition, the results showed that tasked-induced CBF-CBV coupling was stimulus frequency-dependent, i.e., \ = 0.35-0.38 at 4 Hz and \ = 0.51-0.53 at 8 Hz.