Assessing Radiotherapy Responses in Low-Risk Prostate Cancer: A Longitudinal Analysis of T2 Relaxation Times

This is the authors' abstract. We don't add key points for this paper.

Rationale and Objectives To evaluate short and long-term changes in T 2 relaxation as a response to radiotherapy in patients with low and intermediate risk localized prostate cancer. Materials and Methods A total of 24 patients were selected for this retrospective study. Each participant underwent 1.5T magnetic resonance imaging on seven separate occasions: initially after the implantation of gold fiducials, the required step for Cyberknife therapy guidance, followed by MRI scans two weeks post-therapy and monthly thereafter. As part of each MRI scan, the prostate region was manually delineated, and the T 2 relaxation times were calculated for quantitative analysis. The T 2 relaxation times between individual follow-ups were analyzed using Repeated Measures Analysis of Variance. Results Repeated Measures Analysis of Variance (RM-ANOVA) revealed a significant difference across all measurements (F (6, 120) = 0.611, p << 0.001). A Bonferroni post hoc test revealed significant differences in median T 2 values between the baseline and subsequent measurements, particularly between pre-therapy ( M 0 ) and two weeks post-therapy ( M 1 ), as well as during the monthly interval checks ( M 2 - M 6 ). Some cases showed a delayed decrease in relaxation times, indicating the prolonged effects of therapy. Conclusion The changes in T 2 values during the course of radiotherapy can help in monitoring radiotherapy response in unconfirmed patients, quantifying the scarring process, and recognizing the therapy failure.