KEY POINTS
- This retrospective technical note included 41 prostate cancer patients undergoing radiotherapy preparation, using pelvic computed tomography scans to calculate skeletal muscle index at the L3 level.
- The MIM-based method was compared with the validated ImageJ method for skeletal muscle index measurement and sarcopenic classification.
- Agreement was high: mean skeletal muscle index difference was −0.04 cm²/m², p = 0.23, with identical sarcopenic classification in all 41 patients.
- Processing time was significantly shorter with MIM: 3.5 ± 1 minutes versus 10 ± 1 minutes with ImageJ, p < 0.001.
- Reproducibility was excellent, with intraclass correlation coefficient 0.99 for skeletal muscle index and perfect agreement for sarcopenic classification, κ = 1; the automated MIM workflow was faster but overestimated skeletal muscle index by 2.3 cm²/m².
CLINICAL TAKEAWAY
This study shows that sarcopenia screening can be integrated into prostate radiotherapy planning without exporting data to separate body-composition software. The semi-manual MIM method appears accurate, reproducible, and faster than ImageJ, making it practically useful for workflow implementation. The automated workflow is promising but not ready as a drop-in replacement because it systematically overestimated skeletal muscle index and needs further calibration.