Inhomogeneous tissue structures cause spatial-varying water molecule diffusion that is characterized by the spatial derivative of diffusivity, i.e., diffusion gradient. In a magnetic resonance imaging (MRI) system, the effects of diffusion and diffusion gradient are simultaneously encoded in an echo signal using diffusion-encoding magnetic field gradient pulses. A method for imaging the diffusion gradient of water molecules in tissues and for delineating the interface between two tissues having different diffusion properties is disclosed. The method also describes imaging diffusion anisotropy and diffusion gradient simultaneously without any additional scans in comparison with diffusion tensor MRI.