Suppression of Free Fluid Perfusion Artefacts in Velocity Selective ASL Using a BIR-4 T2-FLAIR Preparation

James A. Meakin¹, ², Natalie L. Voets¹, Thomas W. Okell¹, Peter Jezzard¹

Velocity selective arterial spin labeling (VSASL) is not diffusion balanced between the tag and control condition, which causes artefacts from free fluids to appear as positive signal in the perfusion weighted subtractions. This affects both the healthy brain (CSF) and in tumors (inflammation response, edema). Here we present a T2-FLAIR method to null long T1/T2 spins at the time of the velocity selective tag using a segmented BIR-4 inversion. We find that this method increases the accuracy of perfusion measurements with VSASL in healthy grey matter by reducing CSF partial volume effects.