Body MRI artefacts: from image degradation to diagnostic utility.

Magnetic resonance (MR) imaging, as with any other imaging modality, has its share of artefacts, and MR studies of the abdomen and pelvis are particularly affected. These artefacts cause image degradation, can have an adverse effect on imaging quality and are usually considered detrimental. It is thus important to recognise common abdominopelvic MR imaging artefacts and know how to choose protocols and modify scan parameters to eliminate or at least minimise them. Many MR artefacts, on the other hand, provide diagnostically useful information about the underlying tissue, and many powerful MR sequences, such as in-phase or out-of-phase gradient-recalled-echo (GRE) sequences, may be thought of as imaging artefacts applied creatively. To distinguish friend from foe MR artefacts or to convert foes into friends, MR radiologists must recognise and understand the physical basis of such artefacts to take advantage of them for diagnostic purposes.