Conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are assumed to reflect Gaussian distribution models. These images are very useful and have become essential in clinical practice. They can express simple diffusion phenomena, but not complex diffusion phenomena, in a living body more accurately.
The method of diffusion weighting and analysis with regard to the non-normality of diffusion distribution is called “advanced diffusion magnetic resonance imaging” (MRI). Various types of advanced diffusion MRI that are used in clinical practice—q-space diffusion imaging (QSI), diffusion spectrum imaging (DSI), q-ball imaging (QBI), diffusion kurtosis imaging (DKI), and neurite orientation and dispersion density imaging (NODDI)—are described in this paper. In addition, the MR g-ratio, which is expected to be applied in the future, is also reviewed.
Advanced diffusion MRI also has disadvantages: More imaging conditions are necessary, and the scanning time is longer than that with the conventional DWI. However, it is possible to acquire complicated diffusion information in a living body that could not be obtained by DWI or DTI, and this method is provides much information about various diseases. It cannot be undertaken easily and quickly, but further development and use in clinical settings are expected in the future.
抄録全体を表示