Correlation among bioimpedance analysis, sonographic and circumferential measurement in assessment of breast cancer-related arm lymphedema.

New approaches for assessment of lymphedema using ultrasonography (US) have been introduced recently and are reported to be reliable and simple. Ultrasonography provides detailed information about physical properties of the tissue in addition to volume and size. There have been only limited studies comparing bioimpedance analysis (BIA), US, and circumferential measurement (CM), which is considered a standard measurement. The aim of this study was to determine the relationship between US, BIA, and CM. Twenty-eight patients with lymphedema after breast cancer surgery underwent BIA, US, and CM. Impedance, which reflects the amount of extracellular fluid, was measured with 1 kHz frequency in affected and unaffected arms. Circumferences were measured at 10cm proximal and distal to the elbow and a truncated cone method used to calculate estimated volumes for upper arm and forearm. We found that interlimb forearm subcutis thickness differences measured by US were highly correlated with CM measurements and that interlimb upper arm subcutis thickness differences measured by US were moderately correlated with CM measurements and BIA ratios. However, the interlimb ratio of compressibility measured by US showed no or only weak correlation with impedance measurements and circumferential measurements. Our results also show that compressibility measured by US could not be predicted from BIA or CM measurements despite a high degree of concordance among subcutis thickness measured by US, CM, and BIA.