RID11377 chemical shift of second kind

synonym chemical shift cancellation artifact phase cancellation artifact phase interference artifact

definition Local perturbation in magnetic field due to the presence of a ferromagnetic material in or on the patient. The perturbation may produce a spectrum of abnormalities on the image: geometric distortion (in plane or out of plane); signal loss; signal summation (inflection zone) at edge of the region of field distortion; multiple high intensity rings ("vacuum cleaner" artifact); impaired chemical fat saturation.

comment This may manifest as diffuse loss of signal if an object contains a mixture of fat and water protons or as a sharply demarcated black boundary at the interface between water-dominant and fat-dominant objects (boundary effect; black boundary artifact; etching artifact; India ink artifact; relief map artifact)