Magnetic susceptibility artifacts are most prominent with which type of sequences?

Magnetic susceptibility artifacts are most prominent with gradient echo sequences due to their sensitivity to variations in magnetic field homogeneity. Gradient echo sequences use a combination of gradients to refocus the spins during the echo formation, which makes them more vulnerable to inhomogeneities in the magnetic field caused by differences in tissue susceptibility. These variations can lead to phase cancellations or additive effects that result in dark or bright spots on the image, commonly seen at air-tissue interfaces or near metallic objects.

In contrast, spin echo sequences use a 90-degree excitation pulse followed by a 180-degree refocusing pulse, which helps to mitigate the effects of magnetic susceptibility artifacts. The refocusing pulse compensates for the dephasing of spins caused by field inhomogeneities, reducing the likelihood of observing these artifacts. Inversion recovery and fast spin echo sequences also employ similar mechanisms that help minimize the impact of magnetic susceptibility, making them less prone to such artifacts compared to gradient echo sequences.