Background: Early diagnosis of mild lymphedema and treatment are important to prevent its progress. The tissue dielectric constant (TDC), measuring local tissue water in the skin and upper subcutis, has neither been related to the water displacement method (WDM) nor been used to diagnose mild arm lymphedema in patients at risk. Our aims were to evaluate TDC and WDM in combination with palpation, examine the association between TDC and WDM measurements, and compare lymphedema-related factors.
Methods and Results: Seventy-two women treated for breast cancer were diagnosed with mild arm lymphedema using skin palpation in combination with TDC from ﬁxed measurement sites (threshold ratio for upper arm ‡1.45 and forearm ‡1.3) and/or WDM (lymphedema relative volume [LRV]: ‡5% to £8%). Results revealed that 32 (45%) women were diagnosed by TDC only, 19 (26%) by WDM only, and 21 (29%) by both TDC and WDM. TDC ratios exceeding the threshold were most frequently identiﬁed on the medial site of the arm, proximal and distal to the antecubital fossa. TDC and WDM were negatively associated; LRV (r=-0.545, p<0.001). The women diagnosed by TDC only were diagnosed earlier after surgery (p=0.003) and had a lower LRV (1.3%) than those diagnosed by WDM only (6.3%) or both TDC and WDM (6.2%; p<0.001).
Conclusions: TDC and WDM can be used together for early diagnosis of arm lymphedema, but TDC is the most valid method, determining the diagnosis earlier after surgery and at a lower arm volume than WDM.