151751-Najiba-Chargi

56 CHAPTER 4 method was developed to assess SMM on a single CT slide at the level of the third cervical vertebra (C3) in HNC patients. 16 In this method the CSA of both sternocleidomastoid and para- vertebral muscles were measured. However, CSA assessment at this level may be impaired by extension of primary tumor and/or lymph nodes or previous treatment. Moreover, accurate assessment is time consuming. 17,18 There is a need for a reliable index muscle that is consis- tently present on routine imaging, is rarely impacted by disease or treatment and is quick and easy to characterize using commonly used imaging software. For this purpose, we propose the masseter muscle. The masseter muscle has been shown to be adequate in determining SMM and predicting mortality in other fields of medicine. 19–21 The purpose of this study was firstly to investigate whether masseter muscle quantity mea- sures such as masseter cross-sectional area (MCSA), masseter muscle volume (MV), masse - ter muscle maximum thickness (MT) and measurements of muscle quality defined by the Hounsfield unit (HU) and expressed as the average HU of all measured tissue (HU tot ) and in a region of interest (HU ROI ) obtained on routine CT-imaging, correlate with the CSA at C3 and L3. Secondly, we sought to investigate the predictive impact of thesemasseter muscle parameters and overall survival. METHODS AND MATERIALS ETHICAL CONSIDERATIONS Design of this study was approved by the Medical Ethical Research Committee of the University Medical Center Utrecht (approval ID 17-365/C). All procedures in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. PATIENT AND STUDY DESIGN We reviewed patients with newly diagnosed, pathologically proven advanced stage HNSCC who underwent a whole body FDG-PET/CT-scan between 2010 and 2018 at the University Medi - cal Center Utrecht (UMCU), the Netherlands. Patient scans whowere incomplete, of insufficient quality or incompatible with current imaging software were excluded from further analysis. Patient factors with known or expected relation to HNC outcome measures or development of sarcopenia were collected: age at diagnosis, gender, histological diagnosis, comorbidities scored using the Charlson Comorbidity Index (CCI) and the ACE-27 score, tumor site and tumor staging according to the 7 th edition of the UICC TNM classification system, human papilloma - virus (HPV) status for oropharyngeal carcinomas, weight loss 6 months prior to diagnosis and treatment regimens. RADIOLOGICAL ASSESSMENT Segmentation of muscle tissue at the level of C3 and L3 was manually performed using the commercially available software package SliceO-matic (Tomovision, Canada). For analysis