Measurement of Skin Thickness Using Ultra-High-Frequency Ultrasound: A Validated Method with Cutoff Values to Assess...

Evaluation of the severity and progression of lymphedema is challenging, and no universal, simple, and accurate method has been established. The authors propose the use of ultra-high frequency ultrasound (UHFUS) to measure skin thickness for lymphedema assessment.

Skin thickness was measured twice at 8 points in the upper limbs of 40 women (20 with unilateral lymphedema secondary to breast cancer and 20 healthy volunteers) using UHFUS. Measurements were statistically compared with limb circumferences. Receiver operating characteristic curve analysis and a multivariable linear model were performed.

Differences in skin thickness were found between the 2 limbs of patients with lymphedema ( P < 0.001), but not in healthy volunteers. The mean UHFUS examination time per patient was 8 minutes, during which 16 measurements were obtained, with each measurement performed twice. The mean intrarater difference was 0.09 mm. The most useful point for identifying lymphedema was the proximal volar forearm (point 7); a cutoff value of 1.46 mm in skin thickness was established for identifying lymphedema (sensitivity 70%, specificity 100%). Differences in skin thickness between the 2 limbs above 0.28 mm at point 7 identified all included cases of lymphedema (sensitivity 100%, specificity 100%).

Skin thickness measurement using UHFUS is a reproducible, reliable, objective, and rapid method to assess lymphedema, even in initial stages, and to identify the most affected areas in upper limbs. UHFUS also gives more information than limb circumferences, especially at the hand, and may be useful in follow-up.