Systems and methods for radio frequency (RF) based spatial encoding in magnetic resonance imaging using frequency-modulated RF pulses
AssigneeRegents of the University of Minnesota
InventorsMichael Garwood, Efraín Torres, Taylor Froelich
Life of this patent
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Abstract
Radio frequency (“RF”) gradient based magnetic resonance imaging (“MRI”) is provided by establishing a gradient in the RF transmit (B1) field using frequency-modulated RF pulses. A difference between the time-bandwidth product of the frequency-modulated RF pulses can be varied to provide impart different phases to magnetic resonance signals, where these different phases provide phase encoding of the acquired data. The time-bandwidth product difference can be created and varied by changing the pulse duration of one frequency-modulated RF pulse relative to the other while keeping the bandwidth of the pulses constant.
Claims21
A method for magnetic resonance imaging, the method comprising:
- (a) acquiring magnetic resonance data from a subject using a magnetic resonance imaging (MRI) system by:
- generating a pulse sequence with the MRI system, the pulse sequence comprising:
- a radio frequency (RF) excitation pulse;
- a first frequency-modulated RF pulse having a first time-bandwidth product, wherein the first frequency-modulated RF pulse is generated after the RF excitation pulse;
- a second frequency-modulated RF pulse having a second time-bandwidth product, wherein the second frequency-modulated RF pulse is generated after the first frequency-modulated RF pulse;
- acquiring magnetic resonance data with the MRI system by sampling magnetic resonance signals formed in response to the RF excitation pulse, wherein a phase whose value is dependent on the first time-bandwidth product and the second time-bandwidth product is imparted to magnetic resonance signals formed in response to the RF excitation pulse, and a difference between the first time-bandwidth product and the second time-bandwidth product is changed at least one of within the pulse sequence or in repetitions of the pulse sequence in order to phase encode the magnetic resonance data;
- (b) reconstructing an image from the acquired magnetic resonance data.
A method for magnetic resonance imaging, the method comprising:
- (a) acquiring magnetic resonance data from a subject using a magnetic resonance imaging (MRI) system to generate a pulse sequence that phase encodes the magnetic resonance data by imparting a phase to magnetic resonance signals by applying frequency-modulated radio frequency (RF) pulses to the subject, wherein the frequency-modulated RF pulses have variable time-bandwidth products, thereby defining an R-difference value between the frequency-modulated RF pulses, which causes the phase to be imparted to the magnetic resonance signals;
- and
- (b) reconstructing an image from the acquired magnetic resonance data.
Dependencies are inferred from the claim text.