Optimization of parallel acquisition technique in 3D TOF MRA of head with 8-receiving channels phased-array coil in 1.5T MR system: A phantom study / 中国医学影像技术

ABSTRACT

Objective: To explore the application value of array spatial sensitivity encoding technique (ASSET) in 3D TOF MRA of head with 8-receiving channels phased-array coil in 1.5T MR system and the methods to eliminate image artifact, in order to optimize the scanning protocol of 3D TOF MRA. Methods Using the standard model of head for MRI, scanning of 3D TOF MRA was performed combining with different ASSET reduce factor (R value), phase FOV (FOVp), scanning FOV (FOVs) and calibration FOV (FOVc; 30 cm×30 cm in group A, 35 cm×35 cm in group B and 40 cm×40 cm in group C). Then the shortest distance between bilateral wrapped artifacts (D) and SNR was measured, and the acquisition time (TA) of each group and resolution on phase direction (Rp) were recorded. Then the optimized parameters were estimated. Results ASSET artifact became serious as FOVc increased, the distance between wrapped artifact broadened to disappear as FOVs and FOVp increased and R value decreased. TA unchanged as R value and FOVp unchanged. When R value fixed, SNR increased as FOVs and FOVp increased. SNR decreased as R value increased when FOVs and FOVp fixed. Rp decreased as FOVs and FOVp increased. Conclusion ASSET scanning needs right R value matching with corresponding FOVc, FOVs and FOVp. The optimization parameters under the above mentioned condition for 3D TOF MRA of head are FOVc with 35 cm×35 cm, FOVs with 28 cm×28 cm, FOVp with 0.75 and R value with 1.25.