Reliability and Measurement Error of Breast Volume Calculation Using Three-Dimensional Surface Imaging

Background: Breast lymphedema after breast cancer is challenging to quantify. Three-dimensional (3D) surface imaging is one available technique to measure breast volume, however, the measurement properties of available software programs have not been fully determined. The aim of this study was to determine equivalency of measurements with two software programs as well as reliability, standard error of measurement (SEM), and smallest detectable change (SDC). Methods and Results: Retrospective three-dimensional surface imaging (3D-SI) of 100 breasts taken before or after breast conserving surgery for breast cancer were retrieved for reliability analysis. Three assessors followed a standardized measurement technique using two software programs, Vectra (R) 3D Analysis Module (VAM) and Breast Sculptor (R). Mean breast volume was 489.9 +/- 206 cc using VAM and 480.1 +/- 229.1 cc using Breast Sculptor. Lin's concordance showed poor agreement between programs (0.81-0.88). Measurements using VAM had excellent intra- and inter-rater reliability with SEM = 4.1% for one assessor and 8.7% for multiple assessors. Breast Sculptor also had excellent intra-rater and substantial inter-rater reliability but the SEM was much larger at 14.5% (intra-rater) and 19.1% (inter-rater). The SDC value was lowest for VAM and a single rater with 56 cc indicating a meaningful change beyond measurement error. Conclusion: Breast volume measurements captured with 3D-SI using VECTRA-XT are highly reliable, but the volumes, SEM, and SDC varied between the two software programs. Measurement error was lowest with VAM software. Although the usefulness of VECTRA-XT and VAM software to detect change in breast volume is promising, further solutions to reduce measurement error are required to improve clinical utility to measure breast lymphedema.