An Image-based Approach to Understanding the Physics of MR Artifacts

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Principles of physics that underlie propagation of common MR imaging artifacts are explained through a review of clinical images to help readers recognize artifacts, understand their origins, and identify the best methods for reducing them.

As clinical magnetic resonance (MR) imaging becomes more versatile and more complex, it is increasingly difficult to develop and maintain a thorough understanding of the physical principles that govern the changing technology. This is particularly true for practicing radiologists, whose primary obligation is to interpret clinical images and not necessarily to understand complex equations describing the underlying physics. Nevertheless, the physics of MR imaging plays an important role in clinical practice because it determines image quality, and suboptimal image quality may hinder accurate diagnosis. This article provides an image-based explanation of the physics underlying common MR imaging artifacts, offering simple solutions for remedying each type of artifact. Solutions that have emerged from recent technologic advances with which radiologists may not yet be familiar are described in detail. Types of artifacts discussed include those resulting from voluntary and involuntary patient motion, magnetic susceptibility, magnetic field inhomogeneities, gradient nonlinearity, standing waves, aliasing, chemical shift, and signal truncation. With an improved awareness and understanding of these artifacts, radiologists will be better able to modify MR imaging protocols so as to optimize clinical image quality, allowing greater confidence in diagnosis.

© RSNA, 2011


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Article History

Received: Apr 22 2010
Revision requested: June 21 2010
Revision received: Sept 20 2010
Accepted: Oct 11 2010
Published online: May 4 2011
Published in print: May 2011