Magnetization Prepared RApid Gradient-Echo (MP-RAGE) MR imaging of the liver: Comparison with spin-echo imaging

We have implemented an MR technique that employs a rapid gradient echo sequence, preceded by magnetization preparation pulses to provide T 1- and T 2-weighted tissue contrast. With this technique, which can be identified as a member of a new family of pulse sequences, generically named Magnetization Prepared RApid Gradient Echo (MP-RAGE), very short repetition times are used, allowing acquisition times of less than one second and images virtually free of motion-induced artifacts during quiet respiration. Fifteen patients with known liver lesions (metastases, hemangiomas, and cysts) were examined using T 1- and T 2-weighted 2-dimensional MP-RAGE sequences, and the images were compared with conventional T 1- and multi-echo T 2-weighted spin-echo (SE) sequences. Signal difference-to-noise ratios ( SD Ns ) of the lesions were calculated for all pulse sequences using corresponding axial images and were normalized for voxel volume. The mean normalized SD Ns of the MP-RAGE sequences were generally comparable to those for the SE sequences. In addition, there were no noticeable respiratory artifacts on the MP-RAGE images whereas these were clearly present on the T 2-weighted SE images and to a lesser degree on the T 1-weighted SE images. It is concluded that the MP-RAGE technique could become an important method for evaluating the liver for focal disease.