Diffusion MRI (dMRI) is a powerful imaging technique that leverages the diffusion of water molecules within tissues to generate contrast in MRI images. This method provides unique insights into the microstructural properties of biological tissues, particularly the brain’s white matter. By measuring the diffusion of water molecules, dMRI can reveal the underlying architecture of tissues at a microscopic level, which is often beyond the reach of conventional MRI techniques. The core principle of dMRI lies in the diffusion of water molecules, a process driven by thermal energy. Water molecules in biological tissues move randomly, and their movement is influenced by the microenvironment, including cell membranes, organelles, and other structural barriers. This random movement, known as Brownian motion, is characterized by frequent collisions between molecules, which constrain their mobility. In tissues with well-defined structures, such as white matter in the brain, water molecules tend to diffuse along specific directions, reflecting the underlying fiber orientation. This anisotropic diffusion is a key feature that dMRI exploits to generate detailed images of tissue microstructure.