151751-Najiba-Chargi

57 Diagnostics: measuring skeletal muscle mass of the musculus masseter of the CSA at the level of C3, a standard method for slide selection was used, where the first slide to show the entire vertebral arc and the transverse and spinous process when scrolling in a cephalad to caudad direction was selected. Skeletal muscle tissue was identified using HU range settings from -29 to 150 HU and the outer contours of the sternocleidomastoid and paravertebral muscles were tracedmanually. The CSA at the level of C3 was determined as the sum of delineated areas of the paravertebral muscles and both sternocleidomastoid muscles within a HU range of -29 to 150HU in cm 2 . For analysis of the CSA at level L3 the muscle groups analyzed were the psoas, paravertebral and the anterior abdominal wall. For assessment of the masseter muscle, Intellispace (version 14, Phillips, Netherlands) was chosen for its ability to measure the volume of a selected structure (e.g., the masseter muscle) using the Tumor - Tracking feature which allows for rapid tissue volume assessment. Masseter CSAwasmeasured at the level of the dens of the second cervical vertebra (Figure 1). Figure 1. Assessment of the masseter cross sectional area at the level of the 2nd cervical vertebrae. Coronal tilt alignment was made according to a tangent running through the dens and hard palate. Masseter CSA was measured by outlining the outer surfaces of masseter after which IntelliSpace automatically calculated the surface area (mm2), a method independent of the HU value of the defined area. Masseter volume (MV) (cm3) and the total Hounsfield Unit value (HUtot) were automatically calculated after segmenting the entire muscle (Figure 2). 4