Ying Cheng1, 2, Peter C. M. van Zijl, 23, Jun Hua, 24
1Dept. of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2F. M. Kirby Research Center for Functional Brain Imaging, KKI, Baltimore, MD, United States; 3Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 4Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore , MD, United States
Extravascular R2* is an important parameter for quantitative BOLD studies and has been previously determined at 1.5T and 3T. At 7T, only changes in R2* (ΔR2*) upon neuronal stimulation have been reported. In this study, we employed multi-echo vascular-space-occupancy (VASO) MRI to measure absolute parenchymal extravascular R2* values in human brain at 7T. Average extravascular R2* values in human visual cortex at 7T were 43.782.82 s-1 at baseline and 42.713.32 s-1 during visual stimulation (n=4). The extravascular BOLD contributions at 7T were estimated with the ratio of extravascular to total R2* changes during stimulation to be 9011%.
Keywords