MULTISECTION T-1-WEIGHTED HYBRID-RARE - A PULSE SEQUENCE FOR MR-IMAGING OF THE ENTIRE LIVER DURING SUSPENDED RESPIRATION

It is shown that the maximum average-data-collection-speed (ADCS) of m ultisection 2D hybrid-RARE sequences is independent of TR and TE(eff), and a monotonically increasing function of echo-train-length (ETL). T his result was used in the design of an optimized T-1-weighted hybrid- RARE sequence that produces 20 images of the abdomen in 31 s divided i nto four breath-hold periods, The resulting ADCS is 58 lines in k-spac e per second, Twenty-four subjects (2 healthy volunteers and 22 patien ts) were imaged with a protocol that also included: (a) breath-hold T- 1-weighted FLASH which acquires data at 34 lines in k-space per second (49 s scan time), and (b) T-1-weighted conventional spin-echo (9:44 m inutes scan time) with respiratory compensation. The experiments show that this T-1-weighted-hybrid-RARE sequence has: (1) a level of T-1 we ighting that is comparable with the conventional sequences, (2) very l ow vulnerability to susceptibility artifacts, (3) high data acquisitio n efficiency, and (4) higher SNR than T-1-weighted-FLASH. In conclusio n, the T-1-weighted-hybrid-RARE sequence described herein is an effica cious and reproducible technique for rapid imaging of the upper abdome n during suspended respiration.