Prostate Diffusion-weighted Imaging: Selecting the Optimal Repetition Time Using Synthetic Imaging Techniques

The optimal TR for prostate diffusion-weighted imaging (DWI) remains unclear. Given prostate cancers' shorter T1/T2 relaxation times versus benign tissues, TR adjustment may improve contrast. We evaluated 56 clinically significant cancers in 33 patients, comparing synthetic DWI (b-value = 2000 s/mm²) at TR500/1000/1500/2000 ms against conventional TR6000 ms. Assessments included contrast ratio, apparent SNR, lesion conspicuity score, DWI scores based on Prostate Imaging Reporting and Data System (PI-RADS) v2.1, and background suppression. TR6000 showed significantly lower contrast ratio but higher apparent SNR compared with shorter TRs. TR1000-2000 showed higher lesion conspicuity score than TR500, while TR1500-6000 had higher DWI scores than TR500. TR500-1500 provided better background suppression than TR2000/6000. For optimal balance of contrast and noise, TR1000 or TR1500 is recommended for prostate DWI, potentially enhancing prostate cancer detection in clinical practice.