Body MRI artifacts in clinical practice: A physicist's and radiologist's perspective

• Published in: Journal of magnetic resonance imaging Vol. 38; no. 2; pp. 269 - 287
• Main Authors: Graves, Martin J., Mitchell, Donald G.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-08-2013; Wiley Subscription Services, Inc
• Subjects: body imaging; Diagnostic Errors - prevention & control; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; image quality; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Metals; MRI; Prostheses and Implants; Reproducibility of Results; Sensitivity and Specificity; image quality; body imaging; MRI; artifacts
• ISSN: 1053-1807; 1522-2586
• DOI: 10.1002/jmri.24288

The high information content of MRI exams brings with it unintended effects, which we call artifacts. The purpose of this review is to promote understanding of these artifacts, so they can be prevented or properly interpreted to optimize diagnostic effectiveness. We begin by addressing static magnetic field uniformity, which is essential for many techniques, such as fat saturation. Eddy currents, resulting from imperfect gradient pulses, are especially problematic for new techniques that depend on high performance gradient switching. Nonuniformity of the transmit radiofrequency system constitutes another source of artifacts, which are increasingly important as magnetic field strength increases. Defects in the receive portion of the radiofrequency system have become a more complex source of problems as the number of radiofrequency coils, and the sophistication of the analysis of their received signals, has increased. Unwanted signals and noise spikes have many causes, often manifesting as zipper or banding artifacts. These image alterations become particularly severe and complex when they are combined with aliasing effects. Aliasing is one of several phenomena addressed in our final section, on artifacts that derive from encoding the MR signals to produce images, also including those related to parallel imaging, chemical shift, motion, and image subtraction. J. Magn. Reson. Imaging 2013;38:269–287. © 2013 Wiley Periodicals, Inc.