Artifacts and pitfalls in diffusion MR imaging

Although some diffusion-weighted imaging (DWI) techniques have entered the stage of clinical routine application, particularly in the detection of cerebral infarction, obtaining and interpreting diffusion imaging results is not always straightforward. This reflects both the numerous technical difficulties and also the sensitivity of diffusion imaging experiments to phenomena other than diffusion.[1,2] Further complications arise from the sheer number of diffusion parameters that can be derived from the measurement in biological tissue, such as eigenvectors, eigenvalues, anisotropy, and trace of the diffusion tensor, diffusion coefficients for a given direction, and so on. This chapter aims at providing an overview of the most important difficulties encountered in MR diffusion imaging. The parameters derived from DWI can be affected by a number of sources of error. These error sources may be divided into two groups, according to whether they arise from properties of the measurement apparatus or from properties of the measured object itself.