Reliability and Diagnostic Thresholds for Ultrasound Measurements of Dermal Thickness in Breast Lymphedema.

BACKGROUND: Lymphedema of the breast, secondary to treatment for breast cancer, is difficult to assess due to the shape of the breast and the nature of the tissue. Ultrasound measurement of dermal thickness has been previously used to assess breast swelling; however, the reliability of the measurements, or what should be considered an abnormal thickness, is currently known.

METHODS AND RESULTS: Thirty-eight women with breast edema were recruited and underwent assessment using ultrasound. During the assessment, the four quadrants (superior, inferior, medial, and lateral) of the affected and unaffected breasts were imaged three times each. Dermal thickness was then measured by two assessors, on two occasions for each captured image. The interimage, intrarater, and inter-rater reliability was all found to be excellent (Cronbach's alpha = 0.995; ICC(3,1)  = 0.962 and 0.851; and ICC(2,1)  = 0.977, respectively). A dermal thickness of >1.6 mm in the superior and lateral quadrants and 2.0 mm in the medial and inferior quadrants was determined, by receiver-operating characteristics curve analysis, as the optimal diagnostic threshold to detect breast edema.

CONCLUSION: Dermal thickness measurements can be reliably completed on breasts with edema secondary to breast cancer. Future study is needed to determine the utility of the dermal thickness thresholds established as well as to investigate changes in dermal thickness as a response to treatment of breast edema.