Impact of Preparation Phases on Vessel Wall Imaging Using Spiral Image Acquisition at 3 Tesla

Introduction: Coronary vessel wall imaging with MR has the ability to obtain vessel wall thickness and lumen d invasively (1,2,3). Apart from cardiac and respiratory motion, a major challenge of coronary vessel wall imaging is th small thickness (0.5-2mm) and thus the need for high resolution. With the wider spread availability of high field 3T clin higher resolution coronary vessel wall imaging has become more feasible. A previous pilot study using a 3T system gain in SNR of about 50% compared with results obtained at 1.5T (4). The use of more SNR-efficient spiral sequen with the local inversion technique would combine the advantage of high field MRI with the ability of 3D imaging of vessel wall. The main challenge to be overcome is the increased field inhomogeneity (∆f0) at 3T, which especially may use of spiral imaging due to its sensitivity to off-resonances. Therefore the preparation phases for determining the c shim values are of high importance. In particular, f0 may also vary throughout the cardiac and respiratory cycle, requir shimming and f0 determination. In this study we sought to optimize the local inversion pre-pulse technique togethe image acquisition for 3T systems and investigated the impact of the f0 and shimming trigger delay on image qua investigated the effects of small long-term drifts in the magnet field strength that may affect fat sat (SPIR) per performing a f0 shift calibration during the preparation phase.