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MR imaging artifacts that simulate disease: how to recognize and eliminate them
L Arena1, H T Morehouse, J Safir
1Department of Radiology, New York University, NY, USA.
Abstract:
Occasionally, artifacts may simulate pathologic conditions on magnetic resonance (MR) images. Motion artifacts especially affect images of the chest and abdomen. There are a number of techniques for reducing motion artifacts, including respiratory and cardiac gating, k-space phase reordering, gradient moment nulling, even echo rephasing, and physical restraints. Aliasing occurs when the field of view does not include all of the anatomic structures present in the imaged section. Aliasing artifacts can be eliminated by increasing the field of view, oversampling, and use of saturation pulses or surface coils. Truncation artifacts represent the difference between the original and the reconstructed image and can be reduced with data extrapolation algorithms or image filtering. Chemical shift artifacts and magnetic susceptibility artifacts are due to a local deformity of the magnetic field, resulting in spatial misregistration. Chemical shift artifacts are more severe in images acquired with a narrow-bandwidth technique; magnetic susceptibility artifacts are more severe in images acquired with a long echo time. Pitfalls in the interpretation of MR images can be avoided by becoming familiar with the appearances and causes of common MR imaging artifacts.
Insights
Understanding magnetic resonance (MR) imaging artifacts is crucial for accurate diagnosis. This guide details common artifacts like motion, aliasing, truncation, chemical shift, and magnetic susceptibility, along with their causes and mitigation strategies.
Area of Science:
- Medical Imaging
- Radiology
- Magnetic Resonance Imaging (MRI)
Background:
- Image artifacts can mimic pathological conditions in magnetic resonance (MR) imaging.
- Motion artifacts frequently impact thoracic and abdominal MR images.
- Familiarity with artifact causes is essential for accurate MR image interpretation.
Purpose of the Study:
- To elucidate common artifacts encountered in magnetic resonance (MR) imaging.
- To describe the underlying causes and characteristics of various MR imaging artifacts.
- To outline strategies for mitigating or eliminating these artifacts to improve diagnostic accuracy.
Main Methods:
- Review of common magnetic resonance (MR) imaging artifacts, including motion, aliasing, truncation, chemical shift, and magnetic susceptibility.
- Description of techniques for artifact reduction, such as gating, k-space manipulation, field of view adjustment, and specific pulse sequences.
- Explanation of factors influencing artifact severity, including imaging parameters and hardware configurations.
Main Results:
- Motion artifacts can be reduced using techniques like respiratory/cardiac gating and gradient moment nulling.
- Aliasing artifacts are addressed by adjusting the field of view, oversampling, or employing saturation pulses.
- Truncation, chemical shift, and magnetic susceptibility artifacts have distinct causes and mitigation approaches.
Conclusions:
- Recognizing and understanding the origins of common MR imaging artifacts is vital for accurate interpretation.
- Implementing appropriate artifact reduction techniques enhances the diagnostic quality of MR images.
- Knowledge of artifact appearances aids in avoiding diagnostic pitfalls in clinical practice.