Quantification of Radiation-Induced Fibrosis in Head and Neck Cancer Patients Using Shear Wave Elastography

Background Radiation-induced fibrosis (RIF) is a common side effect in head and neck cancer (HNC) patients treated with radiotherapy. A validated tool to measure RIF does not currently exist. In this study, we evaluate the ability of shear wave elastography (SWE) to measure RIF in HNC survivors. Methods HNC patients treated with surgery and adjuvant radiation between January and September 2022 at a single tertiary medical center were enrolled with age and gender-matched control patients. Median tissue stiffness was recorded with SWE at the sternocleidomastoid (SCM) muscle, overlying subcutaneous tissues (ST), and the base of the tongue (BOT). Results A total of 20 patients were included. Tissue stiffness was significantly higher among HNC patients at the SCM ipsilateral (53.7 kPa vs. 17.5 kPa, p=0.002) and contralateral (44.1 kPa vs. 21.6 kPa, p=0.027) than the side of treatment. Tissue stiffness was not significantly different in ST ipsilateral (6.6 kPa vs. 5.3 kPa, p=0.922) or contralateral (8.0 kPa vs. 6.4 kPa, p=0.426) to treatment. Tissue stiffness at the BOT was not significantly different (19.1 kPa vs. 13.1 kPa, p=0.084). Conclusion SWE is a noninvasive method for measuring tissue fibrosis and is a promising tool for the measurement of RIF in patients with HNC. SWE measurements were taken from the SCM, ST, and BOT in HNC patients at least one year out from treatment with surgery and adjuvant radiation as well as age and gender-matched control patients. HNC patients showed significantly higher levels of tissue stiffness at the SCM both ipsilateral and contralateral to radiotherapy. SWE may be useful for tracking the progression of RIF in HNC patients.