Purpose: To measure whole-brain arterial cerebral blood volume (CBVa) using inflow-based vascular-space-occupancy (iVASO) MRI.
Methods: Five healthy volunteers (age=27.2±4.4 years; gender=2F/3M) were scanned on a 3T Philips MRI scanner. Two 3D iVASO protocols with different coverages (whole-brain and partial-brain) were performed with a turbo-field-echo (TFE) readout, as well as a 2D GRE EPI iVASO procedure with three single-slice iVASO scans. The 2D iVASO scan was utilized as the gold standard in this study as it was recently validated in a mouse study using histological markers. In each iVASO protocol, the voxel size is 3x3x6mm³; Eight TR/post-inversion time(TI) pairs: 403/191, 600/277, 800/360, 1000/437, 1500/611, 2000/757, 2700/921, 3500/1059ms were acquired to account for the heterogeneity of vascular transit times and quantify CBVa. To examine macro-vessel effects, a velocity-selective (VS) MR Angiography (MRA) scan was performed. In-house MATLAB programs were used to analyze the data. The fitting was done using Metropolis Hastings algorithm. MRICloud was utilized to segment and identify ROIs. Paired Wilcoxon test was performed in each ROI to compare the CBVa measures in different iVASO protocols. Each participant underwent the same 3D whole-brain iVASO protocol within two weeks, and the coefficient of variation (CV) was calculated to evaluate scan-rescan repeatability.
Results: 3D iVASO and single-slice iVASO can provide consistent CBVa measures. No significant difference was detected between the whole-brain and partial-brain 3D iVASO protocol, which indicates that the imaging slab may not have significant effect on the measured CBVa. Therefore, iVASO MRI can be further tailored to different coverage to be used in various applications. The CV results indicate reasonable reproducibility of iVASO technique.
Conclusion: An optimized 3D iVASO MRI is presented with a TFE readout and whole-brain coverage, which can provide consistent CBVa measures with the original 2D GRE EPI iVASO scan as well as reasonable intra-subject reproducibility.
Not Applicable / None Entered.