Joon DL, et al. - This study sought to determine the vesico-urethral anastomosis (VUA) spatial differences between CT (ctVUA) and MRI (mrVUA) and analyse its impact on the CT defined clinical target volume (ctCTV) in post-prostatectomy radiotherapy (PPRT) as recommended by published guidelines. Researchers realized MRI as important for the accurate delineation of VUA for PPRT.

Methods

• 34 patients with a co-registered simulation CT and T2 weighted MRI were identified.
• In this study, the VUA was located on CT and MRI whilst blinded to the opposing scan.
• Analysis of differences was performed using Wilcoxon’s Signed Rank Test.
• Researchers investigated the mrVUA coverage using three ctCTV margins of 5 mm, 8 mm and 12 mm.

Results

• Median age of the patients was 63 years; 59% indicated pT3a disease; median Gleason score was 7.
• As per findings, the mrVUA was coincident with the ctVUA in 12% and inferior in 88%.
• Observations revealed a median difference of 5 mm (0–10 mm) (P < 0.0001).
• Only a ctCTV margin of 12 mm seemed encompassing all mrVUAs.
• In this study, a ctCTV margin of 8 mm and 5 mm resulted in 12% and 38% cases where the VUA was excluded from the ctCTV.