Artifacts in 3-T MRI: Physical background and reduction strategies
Magnetic resonance imaging (MRI) at a field-strength of 3 T has become more and more frequently used in recent years. In an increasing number of radiological sites, 3-T MRI now starts to play the same role for clinical imaging that was occupied by 1.5-T systems in the past. Because of physical limitations related to the higher field strength and because of protocols transferred from 1.5-T MRI that are not yet fully optimized for 3 T, radiologists and technicians working at these systems are relatively often confronted with image artifacts related to 3-T MRI. The purpose of this review article is to present the most relevant artifacts that arise in 3-T MRI, to provide some physical background on the formation of artifacts, and to suggest strategies to reduce or avoid these artifacts. The discussed artifacts are classified and ordered according to the physical mechanism or property of the MRI system responsible for their occurrence: artifacts caused by B0 inhomogeneity and susceptibility effects, B1 inhomogeneity and wavelength effects, chemical-shift effects, blood flow and magnetohydrodynamics, and artifacts related to SNR.