Tissue Dielectric Constant Combined With Arm Volume Measurement as Complementary Methods in Detection and Assessment of Breast Cancer-Related Lymphedema.

Aim: To investigate the role of tissue dielectric constant (TDC) in the detection and assessment of breast cancer-related lymphedema (BCRL) and to determine whether the TDC could potentially be used as a complementary method for arm volume measurement. Methods: Sixty-nine patients with BCRL were enrolled in this study. Local tissue water was assessed bilaterally by using the TDC method in four sites: upper arm, forearm, hand, and lateral thorax. Arm circumferences were measured at the 4-cm interval, starting from the shoulder to the wrist by using a tape measure. The arm volume was calculated by a standard formula. Patients' demographic information and clinical characteristics were also recorded. Results: Fifty-one of the 69 patients were diagnosed with clinical lymphedema. Using a TDC ratio of 1.2 or a diagnostic reference standard of ≥2 cm arm circumference, the sensitivity of these two methods was found to be identical at 73.9%. The TDC values in four sites on the affected side were significantly higher (p < 0.05) relative to the unaffected side. The inter-side TDC ratio of upper arm and forearm was substantially higher than that of lateral thorax and hand (p < 0.05). The TDC ratio of upper arm, forearm, and hand, especially of the upper arm and forearm, was positively correlated with inter-limb volume difference and stage of lymphedema. Conclusion: The TDC method elucidated a meaningful clinical correlation to the arm volume measurement. Applying those two methods together showed promise in the detection and assessment of BCRL. The forearm and upper arm were reliable examination sites for TDC measurements in the clinic.