# US 2013/0154637 A1 · Measurement of chemical equilibrium ratio using a magnetic resonance spectroscopy system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154637 A1 - Document ID: US20130154637A1 - Status: Published application - Kind: A1 - Application number: 13/330,451 - Filed: 2011-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: General Electric Company - Inventors: Albert Po-Fu Chen; Ralph Eugene Hurd - Web page: https://patentgrep.com/patent/US20130154637A1 ## CPC - A61B 5/055: involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging - A61B 5/14539: {for measuring pH} - G01R 33/4608: {RF excitation sequences for enhanced detection, e.g. NOE, polarisation transfer, selection of a coherence transfer pathway} - G01R 33/4804: {Spatially selective measurement of temperature or pH} - G01R 33/485: based on chemical shift information {[CSI] or spectroscopic imaging, e.g. to acquire the spatial distributions of metabolites} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## 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. ## Claims ### Claim 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 excites a first chemical species, wherein the first tip angle increases a signal-to-noise ratio for the first chemical species relative to a second 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 at the second tip angle that excites at least the second chemical species, wherein the second tip angle substantially preserves the total exchange pool of the first chemical species and the second chemical species; 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. ### Claim 2 (depends on 1) The method of claim 1, wherein the steps of generating the first RF excitation pulse and generating the second RF excitation pulse are interleaved. ### Claim 3 (depends on 1) The method of claim 1, wherein the steps of generating the first RF excitation pulse and generating the second RF excitation pulse are performed simultaneously using a multiband RF pulse. ### Claim 4 (depends on 1) The method of claim 1, comprising the step of determining a pH based on the ratio. ### Claim 5 (depends on 1) The method of claim 1, wherein the step of repeating averages a resonance signal acquired for the first chemical species. ### Claim 6 (depends on 1) The method of claim 1, wherein the step of repeating provides a time resolved measure or spatial encoding of an exchange ratio between the first chemical species and the second chemical species. ### Claim 7 (depends on 1) The method of claim 1, wherein the first tip angle has a first tip angle of 30° or greater ### Claim 8 (depends on 1) The method of claim 1, wherein the second tip angle substantially preserves the total exchange pool of the first chemical species and the second chemical species and that has a second tip angle of less than 30°. ### Claim 9 A memory structure physically encoding one or more executable routines which, when executed, cause acts to be performed comprising: generating a first RF excitation pulse that selectively excites a first chemical species, wherein the first tip angle increases a signal-to-noise ratio for the first chemical species relative to a second 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 at the second tip angle that excites at least the second chemical species, wherein the second tip angle substantially preserves the total exchange pool of the first chemical species and the second chemical species; 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. ### Claim 10 (depends on 9) The memory structure of claim 9, wherein the first RF excitation pulse and the second RF excitation pulse are interleaved. ### Claim 11 (depends on 9) The memory structure of claim 9, wherein the first RF excitation pulse and the second RF excitation pulse are generated simultaneously using a multiband RF pulse. ### Claim 12 (depends on 9) The memory structure of claim 9, wherein the one or more executable routines, when executed, further cause an act to be performed comprising: determining a pH based on the ratio. ### Claim 13 (depends on 9) The memory structure of claim 9, wherein the act of repeating averages a resonance signal acquired for the first chemical species. ### Claim 14 (depends on 9) The memory structure of claim 9, wherein the act of repeating provides a time or spatially resolved measure of an exchange ratio between the first chemical species and the second chemical species. ### Claim 15 A magnetic resonance spectroscopy system, comprising: 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 excites a first chemical species and that has a first tip angle that increases a signal-to-noise ratio for the first chemical species relative to a second tip angle; under equilibrium conditions between the first chemical species and a second chemical species, generation of a second RF excitation pulse at the second tip angle that excites at least the second chemical species; repetition, for a set number of iterations, of the acts of generating the first RF excitation pulse and generating the second RF excitation pulse. ### Claim 16 (depends on 15) The magnetic resonance spectroscopy system of claim 15, wherein the RF coil is also configured to function as a receive coil that detects resonance signals generated in response to the RF pulses. ### Claim 17 (depends on 15) The magnetic resonance spectroscopy system of claim 15, comprising a separate receive coil that that detects resonance signals generated in response to the RF pulses. ### Claim 18 (depends on 15) The magnetic resonance spectroscopy system of claim 15, wherein the first RF excitation pulse and the second RF excitation pulse are interleaved. ### Claim 19 (depends on 15) The magnetic resonance spectroscopy system of claim 15, wherein the first RF excitation pulse and the second RF excitation pulse are generated simultaneously using a multiband RF pulse. ### Claim 20 (depends on 15) The magnetic resonance spectroscopy system of claim 15, wherein the memory further stores instructions to be executed by the one or more control circuits for determining a ratio of the first chemical species and the second chemical species in exchange based on the differential effect of the first tip angle and the second tip angle.