Detect and avoid MR artifacts

Magnetic Resonance Imaging (MRI) offers a variety of contrasts which can be modified by choosing the appropriate sequence parameters. Several tissue parameters and physiological variables influence signal intensity, as relaxation times, spin density, diffusion, oxygenation of blood or blood flow. This multi-parametric dependency of MRI accounts for its excellent soft tissue contrast, but is also the main cause for its high sensitivity to artifacts. This article provides a description of the most important MR artifacts. We focus particularly on the physical and technical principles of the artifacts and on possible workarounds and techniques to allow for artifact-free MR images. (orig.)