Background: Lymphedema often affects the trunk after breast cancer surgery. Measuring volume baseline can help detect lymphedema-related changes early, thereby allowing for early intervention efforts. However, there is no quantitative method for detecting truncal lymphedema. As a preliminary investigation into the development of a new method for measuring truncal lymphedema, this study aimed to investigate the reliability and define the minimal detectable change (MDC) in posterior truncal thickness using a three-dimensional (3D) scanning system. Methods and Results: This observational study included 21 women who had undergone a mastectomy for breast cancer. The 3D images of every subject's trunk were captured by a handheld 3D scanner at two time points. The acquired 3D images were used to calculate the differences in thickness between the affected and unaffected sides at eight points on the trunk. The reliability was determined by checking for agreement between the trials (intraclass correlation coefficient) and by investigating the presence of systematic bias between the measurement error and true value (Bland-Altman analysis). Then, the MDC was calculated. For 14 of the 21 participants, 3D images without missing data at both time points were obtained. Analysis indicated that there was no systematic bias regarding the mean value at the seven body points. Fair-to-excellent reliability was shown at the five points in the middle of the trunk (MDC: 4.14-9.79 mm). The other three points (at the top and bottom of the trunk) had limited reliability. Conclusions: The 3D scanning system effectively measured the differences in thickness between the affected and unaffected sides of participants' posterior trunks, with fair-to-excellent reliability in the middle of the trunk.
Keywords: breast cancer; lymphedema; three-dimensional imaging; truncal lymphedema.