Patent ID: 7132826

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 which includes a gradient waveform G(t) that is applied while acquiring an NMR signal as a series of k-space samples; b) producing first calibration phase data θ 1 (t) by calculating the phase of each k-space sample acquired in step a); c) performing the pulse sequence with the MRI system to acquire a second NMR signal as a series of k-space samples while applying a frequency modulation Δf(t) to the MRI system receiver which offsets the location from which the NMR signal is acquired from the system isocenter; d) producing second calibration phase data θ 2 (t) by calculating the phase of each k-space sample acquired in step c); e) calculating ideal phase data θ IDEAL (t) from the gradient waveform G(t); f) calculating phase error E Δf (t) according to the following equation: E Δf ( t )=θ 2 ( t )−[θ 1 ( t )−θ IDEAL ( t )]; and g) calculating a timing error E t between the applied gradient waveform G(t) and the applied frequency modulation waveform Δf(t) using the phase error E Δf (t) calculated in step f).