Continuous Arterial Spin Labeling at 9.4T: How Long to Label?

Hanbing Lu¹, William Rea¹, Elliot A. Stein¹, Yihong Yang¹

A steady-state condition has often been assumed in ASL quantification. However, when T1 values are remarkably increased at high fields, such as 9.4T, the steady-state condition may not be satisfied when the tagging duration is not sufficiently long. Two practical questions arise: 1) how long should the tagging duration be for reaching a steady-state at 9.4T; and 2) how much error could be potentially introdcued when such assumption is not satisfied. Theoretical analysis and eperimental data are presented. Results show that at 9.4T, short tagging duration (4.8s) does not satisfy the steady-state assumption, systematically underestimating resting-state perfusion values by ~30%. A correction procedure may be required.