Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
226 words
A method of acquiring a magnetic resonance (MR) spatial map with reduced artifacts due to motion, within a subject comprising the steps of: a) placing said subject in a magnetic field to generate longitudinal spin magnetization of nuclear spins having a gyromagnetic ratio, γ, within the subject; b) applying a radio frequency (RF) pulse having a predetermined frequency range to convert longitudinal magnetization into transverse spin magnetization of a selected ensemble of nuclear spins; c) applying a frequency-dephasing magnetic field gradient pulse in a selected direction to dephase transverse spin magnetization by an amount proportional to the spin magnetization's position in the selected direction; d) applying an oscillating frequency-encoding magnetic field gradient pulse in the selected direction where in the oscillating frequency-encoding magnetic field gradient pulse consists of: i) a constant amplitude component whose amplitude is opposite in polarity to the frequency-dephasing magnetic field gradient pulse, and is determined by the selected field-of-view, F, and; ii) an oscillating component whose amplitude, Amp, and frequency are determined by an amount of motion to be compensated; e) detecting, with a sampling period, T s , during the application of the oscillating frequency-encoding magnetic field gradient pulse, magnetic resonance response signals generated by the transverse spin magnetization of the selected ensemble of nuclear spins; f) creating a flow-compensated magnetic resonance spatial map from the detected magnetic resonance response signals.
Claim 2
Independent Claim
226 words
A method of acquiring a magnetic resonance (MR) spatial map with reduced artifacts due to motion, within a subject comprising the steps of: a) placing said subject in a magnetic field to generate longitudinal spin magnetization of nuclear spins having a gyromagnetic ratio, γ, within the subject; b) applying a radio frequency (RF) pulse having a predetermined frequency range to convert longitudinal magnetization into transverse spin magnetization of a selected ensemble of nuclear spins; c) applying a frequency-dephasing magnetic field gradient pulse in a selected direction to dephase transverse spin magnetization by an amount proportional to the spin magnetization's position in the selected direction; d) applying an oscillating frequency-encoding magnetic field gradient pulse in the selected direction where in the oscillating frequency-encoding magnetic field gradient pulse consists of: i) a constant amplitude component whose amplitude is opposite in polarity to the frequency-dephasing magnetic field gradient pulse, and is determined by the selected field-of-view, F, and; ii) an oscillating component whose amplitude, Amp, and frequency are determined by an amount of motion to be compensated; e) detecting, with a sampling period, T s , during the application of the oscillating frequency-encoding magnetic field gradient pulse, magnetic resonance response signals generated by the transverse spin magnetization of the selected ensemble of nuclear spins; f) creating a flow-compensated magnetic resonance spatial map from the detected magnetic resonance response signals.
Claim 3
Dependent Claim
29 words
The method of claim 1 wherein the frequency of oscillation, ω, of the oscillating readout gradient is described by the sampling period, T s , as described by: ##EQU9##
Claim 4
Dependent Claim
57 words
The method of claim 1 wherein the amplitude, Amp, of oscillation of the oscillating readout gradient is described by: ##EQU10## where τ is a time delay measured from substantially the center of the frequency-dephasing magnetic field gradient pulse to a time when the transverse spin magnetization is substantially in phase in response to the oscillating readout gradient.
Claim 5
Dependent Claim
43 words
The method of claim 1 further comprising, after the step of applying the RF pulse, applying a phase-encoding magnetic field gradient pulse in a second selected direction substantially orthogonal to the direction in which the oscillating frequency-encoding magnetic field gradient pulse is applied.