Performance of a fast and high-resolution multi-echo spin-echo sequence for prostate T 2 mapping across multiple systems.

PurposeTo evaluate the performance of a multi-echo spin-echo sequence with k-t undersampling scheme (k-t T-2) in prostate cancer. MethodsPhantom experiments were performed at five systems to estimate the bias, short-term repeatability, and reproducibility across all systems expressed with the within-subject coefficient of variation (wCV). Monthly measurements were performed on two systems for long-term repeatability estimation. To evaluate clinical repeatability, two T-2 maps (voxel size 0.8x0.8x3mm(3); 5min) were acquired at separate visits on one system for 13 prostate cancer patients. Repeatability was assessed per patient in relation to spatial resolution. T-2 values were compared for tumor, peripheral zone, and transition zone. ResultsPhantom measurements showed a small bias (median= -0.9 ms) and good short-term repeatability (median wCV= 0.5%). Long-term repeatability was 0.9 and 1.1% and reproducibility between systems was 1.7%. The median bias observed in patients was -1.1 ms. At voxel level, the median wCV was 15%, dropping to 4% for structures of 0.5cm(3). The median tumor T-2 values (79 ms) were significantly lower (P<0.001) than in the peripheral zone (149 ms), but overlapped with the transition zone (91 ms). ConclusionsReproducible T-2 mapping of the prostate is feasible with good spatial resolution in a clinically reasonable scan time, allowing reliable measurement of T-2 in structures as small as 0.5cm(3). Magn Reson Med 79:1586-1594, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.