Measurement of chemical equilibrium ratio using a magnetic resonance spectroscopy system
First Claim
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1. A method for measuring a ratio of two or more spectrally distinct chemical species in exchange, the method comprising the steps of:
- generating a first RF excitation pulse that selectively tips a first chemical species by a first tip angle;
quantifying the first chemical species based on resonance signals generated in response to the first RF excitation pulse;
under equilibrium conditions between the first chemical species and a second chemical species, generating a second RF excitation pulse that tips at least the second chemical species by a second tip angle that is different than the first tip angle;
quantifying the second chemical species based on resonance signals generated in response to the second RF excitation pulse;
repeating, for a set number of iterations, the steps of generating the first RF excitation pulse, quantifying the first chemical species, generating the second RF excitation pulse, and quantifying the second chemical species; and
obtaining a ratio of the first chemical species and the second chemical species in exchange correcting for the differential effect of the first tip angle and the second tip angle.
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Abstract
The use of selective RF excitation is discussed. A spectrally selective, large tip angle RF pulse is used to detect a weak signal from a first chemical species. A non-selective, small tip angle pulse is used in measuring a signal from a second chemical species in exchange with the first chemical species. The acquired resonance data provides maybe used to measure the ratio of the spectrally distinct species in exchange.
8 Citations
20 Claims
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1. A method for measuring a ratio of two or more spectrally distinct chemical species in exchange, the method comprising the steps of:
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generating a first RF excitation pulse that selectively tips a first chemical species by a first tip angle; quantifying the first chemical species based on resonance signals generated in response to the first RF excitation pulse; under equilibrium conditions between the first chemical species and a second chemical species, generating a second RF excitation pulse that tips at least the second chemical species by a second tip angle that is different than the first tip angle; quantifying the second chemical species based on resonance signals generated in response to the second RF excitation pulse; repeating, for a set number of iterations, the steps of generating the first RF excitation pulse, quantifying the first chemical species, generating the second RF excitation pulse, and quantifying the second chemical species; and obtaining a ratio of the first chemical species and the second chemical species in exchange correcting for the differential effect of the first tip angle and the second tip angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A memory structure physically encoding one or more executable routines which, when executed, cause acts to be performed comprising:
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generating a first RF excitation pulse that selectively tips a first chemical species by a first tip angle; quantifying the first chemical species based on resonance signals generated in response to the first RF excitation pulse; under equilibrium conditions between the first chemical species and a second chemical species, generating a second RF excitation pulse that tips at least the second chemical species by a second tip angle that is different than the first tip angle; quantifying the second chemical species based on resonance signals generated in response to the second RF excitation pulse; repeating, for a set number of iterations, the steps of generating the first RF excitation pulse, quantifying the first chemical species, generating the second RF excitation pulse, and quantifying the second chemical species; and obtaining a ratio of the first chemical species and the second chemical species in exchange correcting for the differential effect of the first tip angle and the second tip angle. - View Dependent Claims (11, 12, 13, 14)
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15. A magnetic resonance spectroscopy system, comprising:
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a primary field coil configured to generate a primary magnetic field within a volume; a radio frequency (RF) coil configured to generate RF pulses; one or more control circuits for controlling operation of the primary field coil and the RF coil; a memory storing instructions to be executed by the one or more control circuits for implementing a pulse sequence, wherein the pulse sequence, when executed, causes generation of a first RF excitation pulse that selectively tips a first chemical species by a first tip angle, wherein the first tip angle increases a signal-to-noise ratio for the first chemical species relative to a second tip angle that is different than the first tip angle; under equilibrium conditions between the first chemical species and a second chemical species, generation of a second RF excitation pulse that tips at least the second chemical species by the second tip angle; repetition, for a set number of iterations, of the acts of generating the first RF excitation pulse and generating the second RF excitation pulse. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification