Abstract
PURPOSE: To evaluate the performance of a multi-echo spin-echo sequence with k-t undersampling scheme (k-t T(2) ) in prostate cancer. METHODS: Phantom 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 0.8 × 0.8 × 3 mm(3) ; 5 min) 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. RESULTS: Phantom 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 0.5 cm(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). CONCLUSIONS: Reproducible 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 0.5 cm(3) . Magn Reson Med 79:1586-1594, 2018. © 2017 International Society for Magnetic Resonance in Medicine.