Temporal Phase Transition Via Fractional Wave Cycle TR in MR Elastography

Bing Wu¹, Yongchuan Lai¹

In MR elastography (MRE), an external driver is used to generate a periodic wave and applied to the subject. A key factor for high quality elastogram is accurate synchronization of the external wave and the motion encoding gradient (MEG). To achieve this, a TR that is the multiple of the wave periods is usually used, which limits the flexibility for TR selection and requires additional discarded data acquisitions (DDA) in the scan. An improvement of the pulse sequence implementation of MRE is proposed. Instead of relying on re-triggering the external wave in every temporal phase, the transition from one temporal phase to the other is achieved by sliding the relative temporal positions of the external wave and MEG. In this way, the TR may be more flexibly selected and also eliminate the need of DDAs.