Magnetic resonance imaging (MRI) and positron emission tomography (PET) are valuable tools for assessing and quantifying tissue-specific features of metabolism or metabolic diseases, such as liver and muscle fat content, liver stiffness, or functional aspects such as glucose uptake dynamics, glycogen storage, inflammatory activities and more.
- MRI-estimated Proton Density Fat Fraction (MRI-PDFF) is an imaging-based biomarker to assess liver fat content and signs of disease. It is particularly useful for NAFLD and NASH.
- Diffusion-Weighted MRI (DW MRI) is a method to assess molecular function and micro-architecture of the human body, as well as liver fibrosis through thermally-driven, random motion of water molecules (inflammation).
- Contrast-Enhanced MRI (CE MRI) is used to detect and assess liver masses and lesions. Gadolinium-based chelated agents (GBCA) and non-GBCA – such as reticuloendothelial (RE) and hepatobiliary (HPB) agents – are used to assess and visualize liver tissue function. The readout can potentially serve as a surrogate biomarker of active inflammatory or fibrotic processes.
- Magnetic Resonance Elastography (MRE) is a non-invasive technique to assess the biomechanical properties of tissues through images of sound wave propagation. The readout is used to quantify and categorize stages of liver stiffness and fibrosis.
- Hyperpolarized contrast media is used in combination with MR data acquisition to assess myocardial and renal metabolism and oxygenation. Chronic ischemia can lead to compromised tissue function.
- Dual-energy absorptiometry (DEXA) is used to assess body composition, measurement of total body fat and breakdown of bone mineral density, fat tissue, and muscle by an enhanced X-ray technology.
- Positron Emission Tomography (PET) is an imaging technique used to assess functional aspects of metabolism, such as the activity and regional distribution of brown adipose tissue. Isotopes are incorporated into biological substances that are metabolized as part of normal physiological processes PET scanning is then used in conjunction with stable isotopes to evaluate the contribution of different metabolic processes from an individual organ, a body area, or even the whole body.