Diffusion-Weighted MR Imaging of the Liver at 3.0 Tesla Using Tracking Only Navigator Echo (TRON): a Feasibility Study

Purpose: To assess the feasibility of TRacking Only Navigator echo (TRON) for diffusion-weighted magnetic resonance imaging (DWI) of the liver at 3.0T. Materials and Methods: Ten volunteers underwent TRON, respiratory triggered, and free breathing DWI of the liver at 3.0 Tesla (T). Scan times were measured. Image sharpness, degree of stair-step and stripe artifacts for the three methods were assessed by two observers. Results: Mean scan times of TRON and respiratory triggered DWI relative to free breathing DWI were 34% and 145% longer respectively. In four of eight comparisons (two observers, two b-values, two slice orientations), TRON DWI image sharpness was significantly better than free breathing DWI, but inferior to respiratory triggered DWI. In two of four comparisons (two observers, two b-values), degree of stair-step artifacts in TRON DWI was significantly lower than in respiratory triggered DWI. Degree of stripe artifacts between the three methods was not significantly different. Conclusion: DWI of the liver at 3.0T using TRON is feasible. Image sharpness in TRON DWI is superior to that in free breathing DWI. Although image sharpness of respiratory triggered DWI is still better, TRON DWI requires less scan time and reduces stair-step artifacts. J. Magn. Reson. Imaging 2009;30:1027–1033. © 2009 Wiley-Liss, Inc.