Exchange-weighted xenon-129 nuclear magnetic resonance system and related method
First Claim
1. A method of characterizing properties of a lung, the lung having at least one compartment therein, said at least one compartment defining at least one reference compartment and the lung having at least one other compartment therein, said at least one other compartment defining at least one target compartment, said method comprising:
- a) introducing hyperpolarized xenon-129 gas in the lung andplacing the lung in a NMR or MRI system;
b) creating transverse magnetization from the hyperpolarized xenon-129 gas in at least one of the reference compartments that has a corresponding chemical shift;
c) leaving the NMR or MRI system unperturbed for an appropriately chosen delay time, whereinsaid delay time is chosen such that a sufficiently large quantity of xenon-129 atoms enter the target compartments from the reference compartment, the xenon-129 transverse magnetization in the target compartments acquires a relatively large range of phase shifts with respect to the transverse magnetization in the reference compartment, and xenon-129 atoms in the target compartments diffuse back to the compartment boundary where they exchange with the reference compartment, thereby defining an exchange process, andupon return to the reference compartment the transverse magnetization is dephased relative to that which remained in the reference compartment and this transverse magnetization from the target compartments thus makes a reduced contribution to the coherent gas-phase signal, which results in a reduced net signal from alveolar gas-phase transverse magnetization compared to the situation wherein there is relatively reduced or no xenon exchange between the reference and target compartments;
d) measuring said signal from hyperpolarized xenon-129 in the reference compartment; and
e) processing said signal from hyperpolarized xenon-129 in the reference compartment to determine a difference in at least one gas-exchange property of said lung among at least two spatial locations;
wherein the target compartment comprises at least a portion of a least one of lung parenchyma and lung alveolar capillary bed, and wherein the reference compartment comprises at least a portion of the lung.
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Abstract
Method and system that provides, among other things, the capability for using hyperpolarized xenon-129 as a probe to non-invasively and non-destructively characterize important properties of certain structures or materials into which hyperpolarized xenon-129 can be introduced and wherein the xenon exists in two or more chemically-shifted states that are in exchange High-resolution MR images can be generated in a fraction of a second wherein the associated signal intensities reflect material properties that characterize the gas exchange among the different states. For example, in the human or animal lung, the system and related method can exploit the differences in gas-exchange characteristics between healthy and diseased lung tissue to generate high-resolution, high signal-to-noise cross-sectional MR images that permit non-invasive regional detection of variations in lung tissue structure with a combination of spatial and temporal resolution that is unmatched by any current imaging modality.
33 Citations
34 Claims
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1. A method of characterizing properties of a lung, the lung having at least one compartment therein, said at least one compartment defining at least one reference compartment and the lung having at least one other compartment therein, said at least one other compartment defining at least one target compartment, said method comprising:
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a) introducing hyperpolarized xenon-129 gas in the lung and placing the lung in a NMR or MRI system; b) creating transverse magnetization from the hyperpolarized xenon-129 gas in at least one of the reference compartments that has a corresponding chemical shift; c) leaving the NMR or MRI system unperturbed for an appropriately chosen delay time, wherein said delay time is chosen such that a sufficiently large quantity of xenon-129 atoms enter the target compartments from the reference compartment, the xenon-129 transverse magnetization in the target compartments acquires a relatively large range of phase shifts with respect to the transverse magnetization in the reference compartment, and xenon-129 atoms in the target compartments diffuse back to the compartment boundary where they exchange with the reference compartment, thereby defining an exchange process, and upon return to the reference compartment the transverse magnetization is dephased relative to that which remained in the reference compartment and this transverse magnetization from the target compartments thus makes a reduced contribution to the coherent gas-phase signal, which results in a reduced net signal from alveolar gas-phase transverse magnetization compared to the situation wherein there is relatively reduced or no xenon exchange between the reference and target compartments; d) measuring said signal from hyperpolarized xenon-129 in the reference compartment; and e) processing said signal from hyperpolarized xenon-129 in the reference compartment to determine a difference in at least one gas-exchange property of said lung among at least two spatial locations; wherein the target compartment comprises at least a portion of a least one of lung parenchyma and lung alveolar capillary bed, and wherein the reference compartment comprises at least a portion of the lung. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for characterizing properties of a lung, the lung having at least one compartment therein, said at least one compartment defining at least one reference compartment and the lung having at least one other compartment therein, said at least one other compartment defining at least one target compartment, said system comprising:
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a) an NMR or MRI system adapted to allow; introduction of hyperpolarized xenon-129 gas in the lung and placement of the lung in an NMR or MRI system; b) said NMR or MRI system adapted to allow; creation of a transverse magnetization from the hyperpolarized xenon-129 gas in at least one of the reference compartments that has a corresponding chemical shift; c) said NMR or MRI system adapted to allow; leaving said NMR or MRI system substantially unperturbed for an appropriately chosen delay time, wherein said delay time is chosen such that a sufficiently large quantity of xenon-129 atoms enter the target compartments from the reference compartment, the xenon-129 transverse magnetization in the target compartments acquires a relatively large range of phase shifts with respect to the transverse magnetization in the reference compartment, and xenon-129 atoms in the target compartments diffuse back to the compartment boundary where they exchange with the reference compartment, thereby defining an exchange process, and upon return to the reference compartment the transverse magnetization is dephased relative to that which remained in the reference compartment and this transverse magnetization from the target compartments thus makes a reduced contribution to the coherent gas-phase signal, which results in a reduced net signal from alveolar gas-phase transverse magnetization compared to the situation wherein there is relatively reduced or no xenon exchange between the reference and target compartments; d) said NMR or MRI system adapted to allow; measurement of said signal from hyperpolarized xenon-129 in the reference compartment; and e) said NMR or MRI system adapted to allow; processing of said signal from hyperpolarized xenon-129 in the reference compartment to determine a difference in at least one gas-exchange property of lung among at least two spatial locations; wherein the target compartment comprises at least a portion of a least one of lung parenchyma and lung alveolar capillary bed, and wherein the reference compartment comprises at least a portion of the lung. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification