Chemical shift artifacts do what as field strength increases?

As the field strength increases in magnetic resonance imaging (MRI), chemical shift artifacts tend to increase. This is primarily due to the way that different chemical environments resonate at slightly different frequencies. At higher magnetic field strengths, the separation between these frequencies becomes more pronounced because the chemical shift is proportional to the magnetic field strength.

In simpler terms, as the field strength rises, the differences in resonance frequencies of fat and water protons, for instance, widen. This distinction leads to a more significant misregistration of the fat and water signals, which manifests as exaggerated chemical shift artifacts in the images. These artifacts appear as dark and bright bands at fat-water interfaces, making the recognition and interpretation of anatomical structures more challenging.

When comparing this with the other options, one can see that because the frequency differences are amplified at higher field strengths, the chemical shift artifacts cannot decrease or remain constant; instead, they reflect an increased visibility. Similarly, the concept of changing direction does not apply here, as the artifacts do not shift laterally but instead intensify in their magnitude.