Speaker
Description
Magnetic resonance imaging (MRI) is a non-ionizing diagnostic technique that detects signals from hydrogen nuclear spins precessing in a strong static magnetic field, $B_0$. Metallic materials commonly used in orthopaedic and dental implants, such as titanium and cobalt-chromium alloys, introduce large magnetic susceptibility differences that significantly distort $B_0$. These distortions lead to rapid intravoxel signal dephasing, severe image artifacts, and signal voids, rendering conventional MRI measurements ineffective in the vicinity of implants.
Previous work has demonstrated that pure phase encoding MRI approaches can be used to measure magnetic field distortions in such extreme off-resonance environments. However, the quality of the resulting field maps is often degraded by aliasing artifacts, particularly in later echo images. In this work, we propose an optimized data sampling scheme that balances image quality and acquisition time, substantially improving the robustness of field mapping near metal.
We apply this approach to measure magnetic field distortions surrounding titanium and cobalt-chromium mouse hip implants. In addition, we extend the analysis from analytical solutions based on idealized geometries to numerical simulations using finite element methods. The strong agreement between experimental measurements and simulations demonstrates that the proposed sampling strategy enables reliable quantitative field mapping in the presence of severe susceptibility-induced distortions. These results provide a foundation for the development of improved spatial encoding schemes for MRI in extreme off-resonance environments.
| Keyword-1 | Magnetic resonance imaging |
|---|---|
| Keyword-2 | Metal implants |
| Keyword-3 | Field distortion |