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Magn Reson Med. 2010 Jun;63(6):1548-56. doi: 10.1002/mrm.22329.

Combined arterial spin label and dynamic susceptibility contrast measurement of cerebral blood flow.

Author information

1
Department of Radiology, Stanford University, Stanford, California 94305-5488, USA. gregz@stanford.edu

Abstract

Dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) are both used to measure cerebral blood flow (CBF), but neither technique is ideal. Absolute DSC-CBF quantitation is challenging due to many uncertainties, including partial- volume errors and nonlinear contrast relaxivity. ASL can measure quantitative CBF in regions with rapidly arriving flow, but CBF is underestimated in regions with delayed arrival. To address both problems, we have derived a patient-specific correction factor, the ratio of ASL- and DSC-CBF, calculated only in short-arrival-time regions (as determined by the DSC-based normalized bolus arrival time [Tmax]). We have compared the combined CBF method to gold-standard xenon CT in 20 patients with cerebrovascular disease, using a range of Tmax threshold levels. Combined ASL and DSC CBF demonstrated quantitative accuracy as good as the ASL technique but with improved correlation in voxels with long Tmax. The ratio of MRI-based CBF to xenon CT CBF (coefficient of variation) was 90 +/- 30% (33%) for combined ASL and DSC CBF, 43 +/- 21% (47%) for DSC, and 91 +/- 31% (34%) for ASL (Tmax threshold 3 sec). These findings suggest that combining ASL and DSC perfusion measurements improves quantitative CBF measurements in patients with cerebrovascular disease.

PMID:
20512858
PMCID:
PMC2905651
DOI:
10.1002/mrm.22329
[Indexed for MEDLINE]
Free PMC Article

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