This document discusses the chemical misregistration artifact, which occurs as a ring of dark signal around organs where fat and water interfaces occur within the same voxel, mainly in the phase direction as it is produced due to the phase difference between fat and water. It is more pronounced in gradient imaging and is caused by fat and water being in and out of phase at different times due to their different precessional frequencies. The artifact can be remedied by selecting an echo time that matches the periodicity of fat and water or using a spin echo sequence instead of a gradient echo sequence.

2. It mainly occurs in the phase direction as it is produced due to the phase difference between the fat an water

6. IP misregistrationyour field strength Fro e.g. at 1.5 T this is a multiple of 4.5 ms educes chemical misregistration artefact

7. Using spin echo sequences rather than gradient echo sequence will reduce this artefact since 1500 RF pulse is very effective in compensating for phase differences.