Water-exchange pharmacokinetic modeling improves DCE-MRI for ROI-based assessment of prostate lesions and of clinically significant prostate cancer.

PURPOSE: Quantitative multiparametric MRI (mpMRI) is increasingly explored for clinically significant prostate cancer (csPCa) detection; however, the diagnostic value of quantitative dynamic contrast-enhanced (DCE)-MRI in prostate cancer remains controversial. In this study, we aim to evaluate the diagnostic performance of water-exchange DCE-MRI in distinguishing prostate tumors from benign tissue and differentiating csPCa from clinically insignificant (CIS) disease. METHODS: This retrospective study included 89 patients who underwent prostate DCE-MRI between March 2022 and October 2023. DCE-MRI quantitative analysis was based on two-site water exchange (2SX) and conventional Tofts model. Tumor, benign and benign prostatic hyperplasia regions of interest were drawn based on quantitative multiparametric MRI. Student's t-test was implemented for intergroup comparisons between benign tissue and tumor, and between CIS and csPCa. Diagnostic performance for differentiating tumor from benign tissue and csPCa from CIS was accessed via linear discriminant analysis with tenfold cross-validation. RESULTS: Fifty-nine patients (mean age ± standard deviation, 69 ± 8 years) were finally included. Most MRI voxels in tumor (86%) and benign tissue (76%) favored 2SX model over Tofts model based on corrected Akaike's Information Criterion. The volume transfer constant (Ktrans) and cellular water efflux rate constant (kio) from 2SX model were significantly higher in tumor regions than benign regions (both P < 0.0001). Compared with the Tofts model, the 2SX model improved discrimination between tumor and benign tissue. Moreover, incorporating kio to correct Ktrans, 2SX model significantly enhanced the ability of Ktrans to differentiate csPCa from CIS compared with Tofts model (area under curve: 0.72 vs 0.63). CONCLUSION: The 2SX model incorporating transmembrane water exchange into quantitative DCE-MRI analysis improves diagnostic performance over the conventional Tofts model alone for distinguishing prostate tumor from benign tissue and for differentiating csPCa from CIS.