The different T2 components composing an MRI signal will, in many cases, reflect the underlying classification of tissues. One simplified model is given by the two-component case of fat and water. The characterization of fat is relevant for the study of many organs and physiological functions including the liver and pancreas, the heart, breast, and general body metabolism. Another major area of interest is the musculoskeletal system, and specifically, the investigation of muscular pathologies such as dystrophy, or neuromuscular disorders.
Mapping the T2 relaxation values can be highly valuable in this case as it can provide information regarding the relative content of fat and water in the tissue. One example is the Charcot-Marie-Tooth disease, characterized by infiltration of fat into the muscle as a result of tissue atrophy. Based on quantitative MRI measurements we develop techniques for fast assessment of fat and water content in vivo, and use these for investigating pathologies in adipose tissues.
Quantification of fat is typically done based on differencs in resonance frequency (chemical shift) between water and fat protons. This is shown in (d) showing fat-water mask produced using gold-standard two-point DIXON technique . We investigate fat from spin-relaxation perspective. A new quantitative MRI technique (the EMC algorithm [33,34]) allows to acquire accurate T2 relaxation maps (a). A two-component postprocessing of the qMRI data allows to classify the tissue into water and fat (c) and furthermore, generate more informative water / fat fraction maps (b).
Applications of this technique include probing fat infiltration into the muscle in Charcot-Marie Tooth disease, monitoring fat levels in liver tissue, separation between white and brown fat and more.