Optimization of Intra-voxel Incoherent Motion Imaging at 3.0 Tesla for Fast Liver Examination

BackgroundOptimization of multi b-values MR protocol for fast intra-voxel incoherent motion imaging of the liver at 3.0 Tesla. MethodsA comparison of four different acquisition protocols were carried out based on estimated IVIM (D-Slow, D-Fast, and f) and ADC-parameters in 25 healthy volunteers. The effects of respiratory gating compared with free breathing acquisition then diffusion gradient scheme (simultaneous or sequential) and finally use of weighted averaging for different b-values were assessed. An optimization study based on Cramer-Rao lower bound theory was then performed to minimize the number of b-values required for a suitable quantification. The duration-optimized protocol was evaluated on 12 patients with chronic liver diseases ResultsNo significant differences of IVIM parameters were observed between the assessed protocols. Only four b-values (0, 12, 82, and 1310 s.mm(-2)) were found mandatory to perform a suitable quantification of IVIM parameters. D-Slow and D-Fast significantly decreased between nonadvanced and advanced fibrosis (P<0.05 and P<0.01) whereas perfusion fraction and ADC variations were not found to be significant. ConclusionResults showed that IVIM could be performed in free breathing, with a weighted-averaging procedure, a simultaneous diffusion gradient scheme and only four optimized b-values (0, 10, 80, and 800) reducing scan duration by a factor of nine compared with a nonoptimized protocol. Preliminary results have shown that parameters such as D-Slow and D-Fast based on optimized IVIM protocol can be relevant biomarkers to distinguish between nonadvanced and advanced fibrosis. J. Magn. Reson. Imaging 2014. (c) 2014 Wiley Periodicals, Inc. J. Magn. Reson. Imaging 2015;41:1209-1217. (c) 2014 Wiley Periodicals, Inc.