Comparison of optimized fast spin echo (FSE) magnetic resonance (MR) imaging to view angle tilt (VAT) FSE in the reduction of metallic susceptibility artifact surrounding arthroplasty

Introduction / Background: MR imaging of arthroplasty has traditionally been limited by the presence of artifact generated by the metallic components, which comparatively demonstrate higher magnetic susceptibility than the adjacent bone and soft tissue (1-3). The sources of these artifacts include induction of radiofrequency eddy currents in the metal, warping of the slice during slice selection, and in-plane off resonance chemical and susceptibility misregistration in the frequency-encoding direction. The intensity of the artifact is related to the degree of relative ferromagnetism of the components, their orientation relative to the external field, as well as the geometry of the implant (1). Metallic susceptibility artifact can be minimized with modification of MR pulse sequence parameters, including the use of a wider receiver bandwidth to minimize the chemical shift generated at the metal-bone and metal-soft tissue interface, as well as high spatial resolution in the frequency direction. View angle tilt (VAT) is an additional method aimed at reducing in-plane geometric distortion from off resonance by adding a gradient in the slice-select axis during signal readout (4,5). The purpose of this study was to make a qualitative comparison of optimized fast spin echo (FSE) MR images to images obtained with VAT.