Patent ID: 7327141

Claim:
A method for calibrating a magnetic resonance imaging (MRI) system prior to the acquisition of an image that is offset from the system isocenter, the steps comprising: a) performing a pulse sequence with the MRI system while acquiring a first NMR free induction decay (FID) signal; b) producing a first calibration phase data set φ 1 (t) by calculating a phase at each of a plurality of points during the first FID signal; c) performing the pulse sequence with the MRI system while applying a frequency demodulation waveform Δf(t) to the MRI system receiver to acquire a second NMR FID signal; d) producing a second calibration phase data set φ 2 (t) by calculating a phase at each of a plurality of points during the second FID signal; e) calculating ideal phase data φ NOMINAL (t) from the frequency modulation waveform Δf(t); f) calculating phase error E φΔf (t) according to the following equation: E φΔf ( t )=φ 2 ( t )−[φ 1 ( t )−φ NOMINAL ( t )]; and g) calculating a timing error τ D representative of a delay between the applied frequency demodulation waveform Δf(t) and the NMR signal using the phase error E φΔf (t) calculated in step f).