What is a major disadvantage of GRE sequences?

The selected answer highlights a significant drawback of Gradient Echo (GRE) sequences, which is their increased sensitivity to magnetic field inhomogeneities. This sensitivity arises from the way GRE sequences acquire data, especially in areas of the body where the magnetic field may not be uniform. Variations in the magnetic field can lead to artifacts such as distortion or decreased image quality, particularly in regions with abrupt changes in tissue type or metallic implants.

Other sequences, more reliant on larger flip angles and longer echo times, might exhibit less susceptibility to these inhomogeneities. Consequently, while GRE sequences can offer advantages like faster image acquisition and high-resolution images in certain contexts, the heightened risk of image artifacts due to magnetic field variations can pose significant challenges, particularly in diagnostic scenarios where precise image quality is essential.

In contrast, options such as shorter scan times, higher signal-to-noise ratios, and enhanced images of soft tissues represent benefits associated with GRE sequences, which is why they are not correct answers in this context.