Prospective motion correction using a wireless device that combines vector observations of the static magnetic field and the rate of change of the gradient fields.

Using external hardware to track patient motion allows for high frequency, accurate prospective motion correction that is robust to changes in coil set-up and subject anatomy. However, this typically comes at the expense of increased hardware complexity, difficulties in marker placement and in some cases cross-calibration. To address some of these challenges, we have developed a small, battery powered marker that uses the three-dimensional gradient spatial encoding, visible through Faraday induction, for vector-based position and orientation estimates. The device enables wireless, calibration-free prospective motion correction that can be used on an ad-hoc basis in an unmodified scanner.