Investigation of Control Scans in Pseudo-Continuous Arterial Spin Labeling (pCASL): Strategies for Improving Sensitivity and Reliability of pCASL

Abstract

Purpose

To investigate the performance of control scans in pseudo-continuous ASL (pCASL) and propose strategies for improving sensitivity and reliability of pCASL.

Methods

The labeling efficiencies of pCASL with conventional control scan and distal control scan were investigated at various radiofrequency (RF) duration/spacing of 0.5/1–2/4 ms, mean slice-selection gradients (GSS) of 1 and 0 mT/m, and total labeling durations of 1.5–3 s, through Bloch equation simulations and in vivo experiments. In addition, the feasibility of three-dimensional (3D) pCASL with the distal control scan and control scan with no RF preparation was demonstrated in a wide brain area, by suppressing the magnetization transfer (MT) effects with high GSS while maintaining the GSS/mean GSS ratio. Results

The distal control scan provided pCASL signals approximately 40% higher and more robust to variations in the labeling conditions than those from the conventional control scan. The distal and no RF control scans with high GSS provided uniform pCASL signals in approximately 8-cm-thick imaging region with MT contributions <10% of the perfusion signals. Conclusions

pCASL perfusion signals can be enhanced (∼40%) and become more stable by using the distal or no RF control scan, which can be applied in a wide area by increasing GSS while maintaining GSS/mean GSS. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.