Optimal Acquisition Strategies for Transit Time Measurement with Continuous ASL

Weiying Dai¹, Ajit Shankaranarayanan², David C. Alsop¹

A good estimate of arterial transit time (ATT) is required to eliminate ATT effects in perfusion measurement with ASL. Multiple delay methods for measuring ATTs can be time consuming. Both a rapid, low resolution scan at multiple labeling delays and more efficient encoding of multiple delay signals using Hadamard encoding can reduce the time penalty. We sought to determine the optimal delays and labeling durations for estimating ATT with continuous labeling using a theoretical model for signal and a Monte Carlo optimization of parameters. Simulations suggest that only two delays and labeling durations are required to estimate ATT and that Hadamard encoding can improve the measurement speed and sensitivity. A low resolution scan at two optimal delays using Hadamard encoding is demonstrated to achieve in-vivo ATT measurement efficiently.