Evaluation of Swallowing Muscles Using Ultrasonography and Shear Wave Elastography in Patients Receiving Radiotherapy for Nasopharyngeal Carcinoma Diagnosis

Overview

The aim of this study is to evaluate the mylohyoid, geniohyoid and digastric muscles in patients with radiotherapy-induced dysphagia due to nasopharynx cancer using ultrasonography and shear wave elastography (SWE).

Post-radiotherapy swallowing dysfunction evaluation was carried out using fibreoptic endoscopic evaluation (FEES), ultrasonography of the swallowing muscles, shear wave elastography and swallowing assessment scale between the dates of 01/01/2023 and 01/06/2023. All patients were interviewed to obtain detailed medical histories. Following this, standardized swallowing assessments were administered, including the Eating Assessment Tool (EAT-10) and the M.D. Anderson Dysphagia Inventory (MDADI). Head and neck examination, endoscopic examination and fibreoptic endoscopic swallowing assessment were performed at the Otorhinolaryngology, Head and Neck Surgery clinic. Penetration Aspiration Score (PAS) was determined by the experienced faculty member. Afterwards, an experienced radiologist performed neck ultrasonography and shear wave elastography (SWE) using an Aplio 500 Platinium Ultrasonography system (Toshiba Medical Systems, Japan) equipped with high-frequency linear transducer (frequency range = 5-14 MHz). With SWE, the stiffness values of the mylohyoid, geniohyoid and digastric muscles were measured in m/s and kPa, and their thickness was measured in mm. The tissue elasticity was outlined using a colour-coded system ranging from dark blue indicating least stiffness to red representing greatest stiffness, with a default measurement range of 0-120 kPa. The elastic value E (kPa) is calculated using the equation E = 3 ρ (m/s) 2. In the equation, m/s represents the shear wave propagation speed, and ρ represents the tissue density (approximately 1 in humans). All patients receiving radiotherapy were treated in our hospital's radiation oncology clinic for Stage I nasopharyngeal cancer received 70 Gy (2,12 Gy/Gun) gross tumour value (CTV70), with 5-10 mm margin for microscopic spread, delivered according to the International Commission on Radiation Units and Measurements (ICRU) Reports 50 and 62 guidelines. After obtaining the data, comparisons between the groups and correlations between the quantitative data were assessed using appropriate statistical methods.