Theoretical models of diffusion-attenuated magnetic resonance signal in biological tissues

Diffusion Magnetic Resonance Imaging (MRI) plays a very important role in studying biological tissue cellular structure and functioning both in health and disease. Proper interpretation of experimental data requires the development of theoretical models that connect the diffusion MRI signal to salient features of tissue microstructure at the cellular level. In this short review, we present some theoretical approaches to describing diffusion-attenuated magnetic resonance signals. These range from the models based on statistical properties of water molecules diffusing in the tissue- cellular environment, to models allowing exact analytical calculation of the magnetic resonance signal in a specific single-compartment environment. Such theoretical analysis gives important insights into mechanisms contributing to the formation of diffusion magnetic resonance signal and its connection to biological tissue cellular structure.