MRI will be carried out at the Liverpool Magnetic Resonance Imaging Centre (LiMRIC), University of Liverpool using a Siemens Symphony 1.5T MR scanner. For body composition, transverse whole-body MRI data will be acquired using a T1-weighted turbo spin-echo (TSE) sequence with 1 cm slice thickness and gap.
From these scans, subcutaneous and visceral fat content will be determined using serial sections of the trunk and skeletal muscle mass from serial sections of the thigh. Liver proton magnetic resonance spectroscopy (1H MRS) will be performed at three standardised sites using the integral body coil with TR 1500 ms TE 135 ms, free breathing. 1H MRS data will be analysed to determine intrahepatic triglyceride concentration as marker of non-alcoholic fatty liver disease. To assess the neck anatomy, T1-weighted TSE axial contiguous 4 mm slices will be acquired from the hard palate to the vocal chords, using a cervical spine coil with participants lying supine and breathing quietly through their nose.25 (link) Within the region of interest, volumetric measurements of submental fat, neck fat, tongue, soft palate, lateral pharyngeal walls and airway will be obtained (figure 2).