Objectives: The aim of this study was to evaluate the utility of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) in monitoring the response to Ra-223 therapy in patients with castration-resistant prostate cancer (CRPC) and bone metastasis.
Materials and methods: This retrospective study included 15 patients with CRPC and bone metastases. DWIBS scans were performed at baseline and after three cycles of Ra-223 therapy. Quantitative analysis of tumor total diffusion volume (tDV) categorized patients as stable disease (DWIBS-SD), partial response (DWIBS-PR), or progressive disease (DWIBS-PD). Kaplan-Meier analysis and log-rank tests were used to assess the correlation between DWIBS findings and survival.
Results: Of the 15 patients (median age 72 years ± 7.3), 7 (47%) were classified as DWIBS-SD, 3 (20%) as DWIBS-PR, and 5 (33%) as DWIBS-PD. DWIBS-PD group had significantly shorter survival than the DWIBS-non-PD group (P = 0.004). Despite no significant differences in age, alkaline phosphatase, prostate-specific antigen or bone metastasis volume, DWIBS-PD group had a significantly higher proportion of patients with Eastern Cooperative Oncology Group performance status score of 2 before the treatment compared to DWIBS-non-PD group (P = 0.039).
Conclusion: DWIBS is a valuable tool for monitoring treatment response and predicting outcome in patients with CRPC undergoing Ra-223 therapy. Early intervention or treatment modification is recommended for patients with DWIBS-PD.
Keywords: Bone neoplasms; Castration-resistant; Castration-resistant prostate cancer; Diffusion magnetic resonance imaging; Prostatic neoplasms; Radium-223.
© 2025. The Author(s).