MRI artifacts are discrepancies or distortions in MRI images that are not a true representation of the anatomy being imaged. These artifacts can arise from various sources, including patient motion, magnetic field inhomogeneity, hardware issues, and physiological factors. Understanding and recognizing these artifacts are crucial for accurate diagnosis and interpretation of MRI images.
Some common types of MRI artifacts include:
Motion artifacts: These occur when the patient moves during the scan, resulting in blurring or ghosting in the image.
Susceptibility artifacts: These arise from variations in magnetic susceptibility within the body, leading to signal loss or distortion, particularly near air-tissue interfaces or metallic implants.
Aliasing artifacts: Also known as wraparound artifacts, these occur when the signal from an object exceeds the maximum frequency encoding, causing it to appear on the opposite side of the image.
Chemical shift artifacts: These occur due to differences in resonant frequencies between fat and water molecules, resulting in misregistration of fat and water signals.
Gradient nonlinearity artifacts: These arise from nonuniformity in the magnetic field gradients, leading to distortions in the image geometry.
RF interference artifacts: These occur due to external electromagnetic interference, such as from nearby electronic devices, causing signal fluctuations or distortion.
Clipping artifacts: These occur when the signal intensity exceeds the dynamic range of the MRI system, resulting in pixel saturation and loss of information.
These are just a few examples, and there are many other types of artifacts that can occur in MRI imaging. Understanding the underlying causes of these artifacts is essential for minimizing their impact on image quality and ensuring accurate diagnosis.
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