Echogenicity, Entropy, and Skin Temperature in Breast Cancer-Related Lymphoedema: A Cross-Sectional Study

Background: Breast cancer–related lymphoedema (BCRL) is a frequent chronic complication associated with structural and functional changes in subcutaneous tissue. This study evaluated subcutaneous echogenicity, entropy, and thickness using ultrasound and examined their relationship with skin temperature measured by infrared thermography in breast cancer survivors. Results: Forty-five women were included (mean age 54.0 ± 7.6 years), of whom 44.4% had BCRL. After statistical adjustment, greater STT in the TB region of the homolateral limb compared with the contralateral limb remained supported, whereas other ultrasound differences were region-specific and exploratory. Participants with BCRL consistently exhibited lower Tmax across all ROIs, representing the most robust finding. Associations between ultrasound parameters and Tmax were limited and region-specific, with a statistically supported association observed only between ENT and Tmax in one forearm region. Methods: This cross-sectional exploratory study included women aged 40–70 years with a history of mastectomy. BCRL was diagnosed by indirect volumetry. Six regions of interest (ROIs) were assessed per limb (C1, C2, C3, TA in the forearm; C4 and TB in the upper arm). Ultrasound images were analysed using ImageJ version 1.54I to quantify subcutaneous tissue thickness (STT), echogenicity (ECHO), and entropy (ENT), while maximum skin temperature (Tmax) was extracted from thermographic images. Analyses accounted for repeated measurements within participants using generalized estimating equations, with adjustment for multiple comparisons. Conclusions: Ultrasonography and thermography capture partially overlapping but distinct structural and functional dimensions of tissue alteration in BCRL.