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AbstractObjective: Dynamic susceptibility-contrast MRI (DSC-MRI) tends to return elevated estimates of cerebral blood flow (CBF) and cerebral blood volume (CBV). In this study, subject-specific calibration factors (CFs), based on steady-state CBV measurements, were applied to rescale the absolute level of DSC-MRI CBF.
Materials and Methods:Twenty healthy volunteers were scanned in a test-retest approach. Independent CBV measurements, for calibration, were accomplished using a T1-based contrast agent steady-state method (referred to as Bookend) as well as a blood-nulling vascular space occupancy (VASO) approach. Calibrated DSC-MRI was compared with pseudo-continuous arterial spin labeling (pCASL).Results: For segmented grey matter (GM) regions of interests (ROIs), pCASL-based CBF was 63±11 ml/(min100g) (mean±SD). Nominal CBF from non-calibrated DSC-MRI was 277±61 ml/(min100g), while calibrations resulted in 56±23 ml/(min100g) (Bookend) and 52±16 ml/(min100g) (VASO). Calibration tended to eliminate the overestimation, although the repeatability was, generally, moderate and the correlation between calibrated DSC-MRI and pCASL was low (r<0.25). However, using GM instead of WM ROIs for extraction of CFs resulted in improved repeatability.
Conclusion:Both calibration approaches provided reasonable absolute levels of GM CBF, although the calibration methods suffered from low signal-to-noise ratio, resulting in weak repeatability and difficulties in showing high degrees of correlation with pCASL measurements.3