Validity and Reliability of Three-Dimensional Imaging for Measuring Breast Cancer-Related Lymphedema in the Upper Limb: A Cross-Sectional Study.

Background: In the past, measurement of upper limb lymphedema was done by water displacement (WD), which is frequently cited as the gold standard. For various reasons, however, the use of WD is restricted in clinical settings. A more precise and easy-to-use method would be favorable. The high precision of three-dimensional (3D) imaging in comparison to WD has already been reported for healthy subjects. The aim of this study is to determine the validity and reliability of 3D imaging by comparing it to the WD method in women with unilateral upper limb lymphedema. Methods and Results: Thirty-nine women with unilateral breast cancer-related lymphedema (BCRL) were included, of which 37 completed two volume measurement techniques (3D and WD) on the BCRL and contralateral healthy arm. Slightly larger volumes were measured by the WD method in healthy arms (+9.8 mL; p  = 0.058) and also in BCRL arms (+18.5 mL; p  < 0.001). All measurements were performed twice by the same researcher to evaluate reliability. There was no significant difference between the two measurements for healthy arms ( p  = 0.323) or BCRL arms ( p  = 0.807) in 3D imaging. Bland-Altman plots showed a high limit of agreement between the single measurements. 3D imaging had a high intrarater reliability (Intraclass Correlation Coefficient = 0.999). Conclusion: Results show that 3D imaging is an innovative method for measuring upper limb volume in BCRL patients. Even though image processing is time consuming, 3D imaging combines high reproducibility with high precision. By software automation, this technique could easily be integrated into clinical routine. It is for this reason that we would recommend implementing the Vectra 3D imaging technique for measurement of BCRL.