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Estimating cerebral blood volume with expanded vascular space occupancy slice coverage
Authors:Christopher B Glielmi  Ronald A Schuchard  XP Hu
Institution:1. Department of Biomedical Engineering, Emory University/Georgia Institute of Technology, Atlanta, Georgia, USA;2. Veterans Administration Rehabilitation Research and Development Center of Excellence, Atlanta, Georgia, USA;3. Department of Neurology, Emory University, Atlanta, Georgia, USA
Abstract:A model for quantifying cerebral blood volume (CBV) based on the vascular space occupancy (VASO) technique and varying the extent of blood nulling yielding task‐related signal changes with various amounts of blood oxygenation level‐dependent (BOLD) and VASO weightings was previously described. Challenges associated with VASO include limited slice coverage and the confounding inflow of fresh blood. In this work, an approach that extends the previous model to multiple slices and accounts for the inflow effect is described and applied to data from a multiecho sequence simultaneously acquiring VASO, cerebral blood flow (CBF), and BOLD images. This method led to CBV values (7.9 ± 0.3 and 5.6 ± 0.3 ml blood/100 ml brain during activation CBVACT] and rest CBVREST], respectively) consistent with previous studies using similar visual stimuli. Furthermore, an increase in effective blood relaxation (0.65 ± 0.01) compared to the published value (0.62) was detected, likely reflecting inflow of fresh blood. Finally, cerebral metabolic rate of oxygen (CMRO2) estimates using a multiple compartment model without assumption of CBVREST led to estimates (18.7 ± 17.0%) that were within published ranges. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Keywords:vascular space occupancy  cerebral blood volume  cerebral blood flow  blood oxygenation level‐dependent  cerebral metabolic rate of oxygen
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