Analysis of Complex Flow Patterns with Acceleration-Encoded MRI

Introduction: The phase contrast principle (PC) can be employed to measure flow acceleration by using acceleration sensitive encoding gradients. The direct assessment of regional acceleration can provide valuable information regarding changes in timing (temporal acceleration) and direction (convective acceleration) of flow. Although acceleration data may be estimated from velocity encoded images, the direct measurement of acceleration may be advantageous due to amplification of velocity noise by error propagation when calculating spatiotemporal velocity derivatives [1-3]. The aim of this study was to evaluate a newly developed gradient optimized acceleration-sensitive MRI technique with full three-directional acceleration encoding of aortic blood flow. Results were compared to standard velocity encoded phase contrast MRI. In addition, the value of acceleration induced intravoxel dephasing as a new image contrast providing information about complex and vortical flow was investigated.