Novel method of Ultrashort TE 4D MR Angiography – Continuous Acquisition Variable TR (CAVTR) with View Sharing.

Motivation: The conventional multi-phase Pulsed ASL UTE 4D MRA sometimes provides insufficient signal intensity to visualize hemodynamic flow characteristics in late phases. Goal(s): Our goal is to improve the visibility of multi-phase Pulsed ASL UTE 4D MRA. Approach: We developed a novel method, Continuous Acquisition Variable TR (CAVTR) UTE 4D MRA pulse sequence which utilizes continuously increasing TR. This new pulse sequence has less signal fluctuation and can avoid late phase signal reduction. We combined CAVTR with view sharing and improved late phase image quality without detriment to temporal resolution. Results: This novel method can improve clinical usability of non-contrast ASL based UTE 4D-MRA. Impact: The novel method, Continuous Acquisition Variable TR pulse sequence with View Sharing achieved both high temporal resolution and good visibility of arteries in late phases. This novel method can improve clinical usability of non-contrast ASL based UTE 4D-MRA.