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.