Technical Feasibility of IVIM for Prostate Cancer Imaging Using High-Amplitude Whole-Body Gradient System With Spiral Readout and Velocity-Compensated Diffusion Encoding.

Intravoxel incoherent motion (IVIM) is sensitive to tissue diffusion and perfusion and has spurred great interest in various pathologies such as prostate cancer. However, poor repeatability and reproducibility of IVIM parameters hamper its wide-scale adoption in the clinics. To address this, improvements to the IVIM data acquisition and analysis are necessary. The purpose of this study was to develop a framework for high-quality IVIM imaging of the prostate. To boost signal precision and quality of IVIM parameter maps, we used a custom pulse sequence to combine velocity-compensated diffusion encoding with spiral readout at a high-performance 3 T MRI system with 300 mT/m gradients. IVIM parameters were evaluated in a cohort of five men with and without prostate cancer. Technical performance was assessed in terms of the signal-to-noise ratio (SNR), visual quality of IVIM parameter maps and parameter repeatability. High in-plane resolution images of the prostate were obtained with SNR > 3 (i.e., noise floor level) in 91% of voxels at the highest b-value of 500 s/mm2. The parameter maps exhibited high quality with fine features recovered in tissue diffusivity and perfusion fraction maps. Voxel-wise and ROI-based analysis revealed high repeatability of the parameters at single subject and group level across main prostatic tissue classes (peripheral and transitional zones) and prostate cancer. A combination of velocity-compensated diffusion encoding, spiral readout and strong gradients enables high-quality IVIM imaging in the prostate. Our framework may advance IVIM as a reliable imaging biomarker in prostate.