Susceptibility mri artefacts

Susceptibility artifacts in MRI occur due to local magnetic field inhomogeneities caused by differences in magnetic susceptibility between tissues or between tissues and foreign materials. These artifacts result in signal loss, geometric distortion, or blooming effects on images.

Common Causes of Susceptibility Artifacts

Cause	Description
Air-tissue interfaces	Sinuses, lungs, bowel gas induce distortion
Metal implants	Orthopedic hardware, dental fillings cause large distortions and signal voids
Hemorrhage	Blood degradation products (deoxyhemoglobin, hemosiderin) cause blooming
Calcifications	Can mimic susceptibility effects due to diamagnetic property
Surgical clips and devices	Cause signal voids and distortion
Dental hardware	Common artifact source in head and neck imaging

Imaging Features

Signal void or hypointensity on T2*-weighted and susceptibility-weighted images (SWI).
Blooming artifact exaggerates size of paramagnetic substances.
Geometric distortion near air-bone or metal-tissue boundaries.
Can obscure adjacent anatomy or pathology, limiting diagnostic accuracy.

Clinical Impact

Artifacts may mimic pathology or obscure lesions.
Important to recognize and differentiate from true pathology.
Sequence optimization (e.g., spin-echo vs gradient-echo) and artifact reduction techniques help minimize impact.

Susceptibility artifacts are especially prominent on gradient-echo and SWI sequences due to their sensitivity to magnetic field differences.