EVALUATION OF TIME-OF-FLIGHT AND PHASE-CONTRAST MRA SEQUENCES AT 1.0 T FOR DIAGNOSIS OF CAROTID-ARTERY DISEASE .1. A PHANTOM AND VOLUNTEER STUDY

Purpose and Material: The aim of this work was, firstly, to compare di fferent manufacturer-provided MRA sequences in a 1.0 T MR unit, with r espect to the visibility of an artificial stenosis in a flow phantom a nd, secondly, to evaluate the same sequences in healthy volunteers wit h respect to S/N ratio levels and practical in vivo implementation rou tines. Methods: The studied sequences were 2D and 3D TOF and sequences with an acquisition time of approximately 10 min. Quantitative signal evaluation was made using single transverse partitions in all phantom experiments. MIP angiograms and MPR reconstructions were made for vis ual inspection of image quality. In vivo, the images were individually evaluated by visual inspection by experienced neuroradiologists. Resu lts: In the evaluation of the grade and length of a stenosis; a combin ation of MIP and MPR was seen to be the optimal and necessary procedur e. A shortening of TE played an important and significant role in the visualization of the poststenotic flow in the phantom using TOF MRA. H owever: the shortest TE values gave poor S/N ratio in vivo. The good r esults achieved in the phantom studies for 3D phase-contrast were some what reversed in the volunteer studies, whereas 3D TOF sequences showe d good results in both the phantom and the volunteer studies.