Harmonization of cerebral blood flow measurements by multi-delay 3D gradient and spin echo, and single-delay 2D echo planar imaging
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Purpose
Cerebral blood flow (CBF) is commonly measured by pseudo-continuous arterial spin labeling (PCASL) in human research, but recent advancements in methodology have limited data reuse. The object of this work is to harmonize two distinct PCASL techniques within a cohort with a wide range of CBF values.
Methods
Participants had two PCASL sequences collected within a single session: a single post-label delay sequence with a 2D echo-planar imaging (EPI) readout, “CBF 2D,1PLD ”, and a five post-label delay sequence with gradient and spin echo (GRASE) 3D readout, “CBF 3D,5PLD ”. Linear regression modeling to impute CBF 3D,5PLD from CBF 2D,1PLD , hemoglobin, and age were assessed within gray matter (GM) and white matter (WM) using leave-one-out cross-validation for prediction errors and confidence intervals. Within-subject coefficient of variation (wsCV) and inter-class correlation coefficient (ICC) were calculated using CBF 3D,5PLD imputed vs. measured as pseudo test-retest pairs.
Results
Fifty participants, ages 8–45 (median 25) years, had usable CBF 3D,5PLD and CBF 2D,1PLD , including 17 participants with sickle cell disease (SCD), who were matched by age ( p = 0.90) and sex ( p = 0.16) to those without SCD. A multiple linear regression model including hemoglobin and age fit GM CBF (R 2 adj. = 0.82; for WM CBF R 2 adj. = 0.78). The wsCV for CBF 3D,5PLD was 9.1% for GM, 11.3% for WM. ICC was 0.89 for GM and 0.87 for WM. Models without age or hemoglobin fit slightly worse.
Conclusion
Our study demonstrates feasibility to impute 3D-GRASE multi-PLD CBF from a 2D-EPI single-PLD technique, which promotes data sharing and harmonization.
