Accelerated 3D T2w-imaging of the prostate with 1-millimeter isotropic resolution in less than 3 minutes

Abstract

Purpose: To achieve 3D T2w imaging of the prostate with 1-mm isotropic resolution in less than 3 min. Methods: We devised and implemented a 3D T2-prepared multishot balanced steady state free precession (T2prep-bSSFP) acquisition sequence with a variable density undersampled trajectory combined with a total variation regularized iterative SENSE (TV-SENSE) reconstruction. Prospectively undersampled images of the prostate (acceleration factor R = 3) were acquired in 11 healthy subjects in an institutional review board-approved study. Image quality metrics (subjective signal-to-noise ratio, contrast, sharpness, and overall prostate image quality) were evaluated by 2 radiologists. Scores of the proposed accelerated sequence were compared using the Wilcoxon signed-rank and Kruskal-Wallis non-parametric tests to prostate images acquired using a fully sampled 3D T2prep-bSSFP acquisition, and with clinical standard 2D and 3D turbo spin echo (TSE) T2w acquisitions. A P-value < 0.05 was considered significant. Results: The 3× accelerated 3D T2prep-bSSFP images required a scan time (min:s) of 2:45, while the fully sampled 3D T2prep-bSSFP and clinical standard 3D TSE images were acquired in 8:23 and 7:29, respectively. Image quality scores (contrast, sharpness, and overall prostate image quality) of the accelerated 3D T2prep-bSSFP, fully sampled T2prep-bSSFP, and clinical standard 3D TSE acquisitions along all 3 spatial dimensions were not significantly different (P > 0.05). Conclusion: 3D T2w images of the prostate with 1-mm isotropic resolution can be acquired in less than 3 min, with image quality that is comparable to a clinical standard 3D TSE sequence but only takes a third of the acquisition time.