A 1H-MRS would be performed to measure cardiac fat accumulation using a 1.5 T whole-body MR scanner (MAGNETOM AvantoSQ 1.5 T B-19; Siemens) run by specialists using dedicated software (Argus; Siemens). The method used to measure cardiac fat accumulation with 1H-MRS has been previously validated [35 (link)–37 (link)]. The volume of interest (VOI = 10 × 10 × 20 mm3) would be manually placed on the ventricular septum of the cine images of the heart and adjusted to fit the ventricular septum of the left ventricle. The spectra of lipid and water would be acquired by point-resolved spectroscopy sequences (repetition time/echo time ms 4000/30). The myocardial signal would be quantified as triglyceride signal intensity at 1.4 ppm from the spectra with water suppression, and water signals would be quantified at 4.7 ppm from the spectra without water suppression.
Similarly, VOI (20 × 20 × 20 mm3) would be set on the liver and tibialis anterior muscle on the acquired MR data, avoiding liver edges, visible blood vessels, or bile ducts. The MR spectral raw data would then be processed to calculate intrahepatic lipid content, intramyocellular lipid content, and extramyocellular lipid content using LC model software (version 6.3-1J; Stephen Provencher, Oakville, ON, Canada). Each lipid would be estimated by an indicator as a ratio of lipid to water.
Similarly, VOI (20 × 20 × 20 mm3) would be set on the liver and tibialis anterior muscle on the acquired MR data, avoiding liver edges, visible blood vessels, or bile ducts. The MR spectral raw data would then be processed to calculate intrahepatic lipid content, intramyocellular lipid content, and extramyocellular lipid content using LC model software (version 6.3-1J; Stephen Provencher, Oakville, ON, Canada). Each lipid would be estimated by an indicator as a ratio of lipid to water.