An optimized velocity selective arterial spin labeling module with reduced eddy current sensitivity for improved perfusion quantification
Meakin JA., Jezzard P.
Velocity-selective (VS) arterial spin labeling is a promising method for measuring perfusion in areas of slow or collateral flow by eliminating the bolus arrival delay associated with other spin labeling techniques. However, B 0 and B 1 inhomogeneities and eddy currents during the VS preparation hinder accurate quantification of perfusion with VS arterial spin labeling. In this study, it is demonstrated through simulations and experiments in healthy volunteers that eddy currents cause erroneous tagging of static tissue. Consequently, mean gray matter perfusion is overestimated by up to a factor of 2, depending on the VS preparation used. A novel eight-segment B 1 insensitive rotation VS preparation is proposed to reduce eddy current effects while maintaining the B 0 and B 1 insensitivity of previous preparations. Compared to two previous VS preparations, the eight-segment B 1 insensitive rotation is the most robust to eddy currents and should improve the quality and reliability of VS arterial spin labeling measurements in future studies. Copyright © 2012 Wiley Periodicals, Inc.