Quantification of intramuscular fat in fish by MRI
Quantification du gras intramusculaire chez le poisson par IRM
Résumé
The aim of this work was to test the MRI water/fat separation methods used in clinical applications, for the quantification of intramuscular lipids on salmon cutlets. Results were validated using NMR. MRI images of 30 cutlets were acquired at 1.5T at 6 acquisition times, allowing the computation of water-only and fat-only images. The cutlets were then ground, sampled and dried for fat quantification by NMR giving a fat fraction in g/g. The fat fraction computed from water-only and fat-only images was corrected to get a g/g result. Indeed their intensities are not proportional to weight but to the number of protons. Moreover, many macromolecules such as proteins do not give any signal in MRI. So, we corrected the water-only and fat-only images to obtain a fat fraction in g/g, by correcting with the proton density of fat and water and with the hypothesis of an average water content (70%) for each cutlet. The R2 and the slope of the linear relation between MRI and NMR were equal to 0.96 and 1.03. These results showed that MRI water/fat separation technique is a convenient tool to quantify fat in salmon.