MRI artifact

Distortions in MRI images

MRI Artifacts

Motion artifacts in MRI

MRI artifacts are distortions or errors in magnetic resonance imaging (MRI) images that can obscure or mimic pathology. These artifacts can arise from various sources, including patient movement, hardware limitations, and specific imaging sequences. Understanding and identifying these artifacts is crucial for accurate diagnosis and image interpretation.

Types of MRI Artifacts

Motion Artifacts

Motion artifacts occur when the patient moves during the MRI scan. This can result in blurring or ghosting of the image. These artifacts are particularly common in scans of the abdomen or chest, where breathing can cause significant movement.

Flow Artifacts

Flow-related signal loss in MRI

Flow artifacts are caused by the movement of blood or other fluids within the body. These can appear as signal voids or distortions in the image, often seen in vascular structures.

Metal Artifacts

Metal artifacts in MRI

Head MRI with metal artifacts

Metal artifacts occur when metallic objects within the body, such as surgical implants, interact with the magnetic field. These artifacts can cause significant distortion and signal voids, making it difficult to visualize the surrounding anatomy.

Chemical Shift Artifacts

Chemical shift artifact in MRI

Chemical shift artifacts arise due to differences in the resonant frequencies of fat and water protons. This can lead to misregistration of fat and water signals, resulting in a dark or bright band at the interface of fat and water tissues.

Wrap Around Artifacts

Wrap around artifacts in head MRI

Wrap around artifacts, also known as aliasing, occur when the field of view is smaller than the body part being imaged. This results in overlapping of anatomical structures from outside the field of view onto the image.

Causes and Prevention

Patient Movement

To minimize motion artifacts, patients are often instructed to remain still during the scan. Breath-hold techniques and sedation may be used in certain cases to reduce movement.

Hardware Limitations

Artifacts can also result from limitations in the MRI hardware, such as gradient coil imperfections or radiofrequency inhomogeneities. Regular maintenance and calibration of MRI machines can help reduce these issues.

Sequence Parameters

Adjusting the imaging sequence parameters, such as echo time and repetition time, can help mitigate certain artifacts. For example, using fat suppression techniques can reduce chemical shift artifacts.

Related Pages

• Magnetic resonance imaging
• Radiology
• Medical imaging