NMR Relaxometry and Imaging to quantify the fat-to water ratio in muscle tissue

Fat suppression in Magnetic Resonance Imaging (MRI) images is an important diagnostic topic. In this work, through NMR Relaxometry and Imaging of 1H nuclei we estimated the Fat/Water (F/W) ratio on pig loins, assumed as model of human muscle tissue, by analyzing 1H longitudinal relaxation times (T1) distributions and quantitative MRI images. It is known that water and fat proton signals in tissues have different T1 values. The innovative characteristic of our approach is to assume that T1 values follow a quasi-continuous distribution, instead of a discrete distribution. F/W ratios of the samples were determined through NMR Relaxometry by distinguishing the signal of fat 1H nuclei from that of the water through the choice of a proper cut-off on the T1 distributions. F/W ratio was determined on MRI images acquired with the “classic” Short Time Inversion Recovery sequence. Innovative Parametrically Enabled Relaxation Filters with Double and multiple Inversion (PERFIDI) sequences, that implement band-pass filters, were also used. The correlation between NMR and an independent destructive chemical analysis performed on the same samples gave very good results for both Relaxometry and Imaging techniques.