Ultra-sound Shear Wave Elastography Tissue Stiffness and Thickness Assessment After Adjuvant Radiotherapy for Breast Cancer Treatment; An Exploratory Study.

Purpose: This research investigated the feasibility of using B-mode ultrasound with shear-wave elastography (SWE) to evaluate the structural and mechanical properties of multiple tissue layers in the pectoral region of women with chronic radiation fibrosis following breast cancer treatment. Method: Nine women between one and five years post unilateral conventional fractionated radiotherapy were evaluated. Both ultrasound and SWE were used to examine the thickness and stiffness of skin, subcutaneous adipose tissue, fascia and muscle in both their irradiated and non-irradiated sides. Linear mixed models were conducted to examine statistical differences in tissue thickness and stiffness between irradiated and non-irradiated sides with the arm resting by the side and also in abduction. Results: Significant differences were found between irradiated and non-irradiated tissues. Irradiated skin was significantly thicker (p=0.020) and stiffer (p<0.001) with the arm by the side. Irradiated subcutaneous adipose tissue was significantly thinner (p<0.001). Irradiated fascia and muscles thinned significantly with the arm moved out to abduction position. Irradiated pectoral muscle was significantly stiffer (p=0.004), this stiffness amplified with arm abduction (p<0.001) where the muscle thinned significantly (P<0.001).Conclusion: Ultrasound with SWE shows potential to provide novel objective evaluation of radiation induced soft tissue fibrosis at multiple tissue layers in the pectoral region. Tissue thickness changes in irradiated tissue were evident in ultrasound images. Quantifying these tissue changes supports research development and introduction of clinical interventions to ameliorate the symptoms of morbidity that is currently considered irreversible.