A Fast and Robust Method for Off-Resonance Detection in Metal Implant Imaging

Theresa Bachschmidt¹, ², Mathias Nittka¹, Peter M. Jakob²

Field inhomogeneities are the dominant source for artifacts in images of volumes containing metal implants. They can be determined by measurement of the geometric distortion of the slice profile. Its shape is determined by the amplitude and polarity of the readout gradient. This work depicts analytically two inaccuracies of this method, both based on the fact that slices are not infinitely thin and suggests solutions. Application of readout gradients with amplitudes in the range of the slice select gradient require opposite polarity relative to the slice select gradient. The application of two different readout gradients can resolve the inaccuracy of the excitation bandwidth.