Methods for imaging pulmonary and cardiac vasculature and evaluating blood flow using dissolved polarized 129Xe
First Claim
1. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
- delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse;
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said delivering step includes having the patient inhale the polarized 129Xe gas into the lungs, the polarized 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, and wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, and wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate wherein a differential MRI image is obtained which comprising data associated with the physiology of the lungs of the patient, the physiology of the vasculature of the patient, blood flow in the patient, and perfusion in the patient, the data corresponding to both the 129Xe gas and dissolved-gas phase, and wherein said differential image is obtained by exciting the 129Xe gas phase with an RF pulse having an excitation pulse frequency which corresponds to the resonance of the gas phase and exciting the dissolved phase with an RF pulse having an excitation frequency which corresponds to the resonance of the dissolved phase, and wherein the gas phase RF excitation pulse is a small flip angle pulse and the dissolved phase RF excitation pulse is a large flip angle pulse.
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Abstract
MR spectroscopy and imaging method for imaging pulmonary and cardiac vasculature and the cardiac region and evaluating blood flow or circulatory deficits use dissolved phase polarized 129Xe gas and large flip angle excitation pulses. Pulmonary and cardiac vasculature MRI images are obtained by delivering gas to a patient via inhalation such as with a breath-hold delivery-procedure, exciting the dissolved phase gas with a large flip angle pulse, and generating a corresponding image. Preferably, the image is obtained using multi-echo imaging techniques. Blood flow is quantified using low field MR spectroscopy and an RF excitation pulse with a frequency which corresponds to the resonance of the dissolved phase 129Xe.
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Citations
52 Claims
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1. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse;
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said delivering step includes having the patient inhale the polarized 129Xe gas into the lungs, the polarized 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, and wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, and wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate wherein a differential MRI image is obtained which comprising data associated with the physiology of the lungs of the patient, the physiology of the vasculature of the patient, blood flow in the patient, and perfusion in the patient, the data corresponding to both the 129Xe gas and dissolved-gas phase, and wherein said differential image is obtained by exciting the 129Xe gas phase with an RF pulse having an excitation pulse frequency which corresponds to the resonance of the gas phase and exciting the dissolved phase with an RF pulse having an excitation frequency which corresponds to the resonance of the dissolved phase, and wherein the gas phase RF excitation pulse is a small flip angle pulse and the dissolved phase RF excitation pulse is a large flip angle pulse. - View Dependent Claims (5, 6)
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2. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse;
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said delivering step comprises having the patient inhale the polarized 129Xe gas into the lungs, the polarized 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, and wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, and wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate; and
delivering via inhalation a quantity of polarized 3He gas, and wherein a MRI differential image is obtained comprising data corresponding to the polarized gas 3He in the lungs in addition to the dissolved phase polarized 129Xe.
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3. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, wherein said delivering step comprises inhalation of the polarized 129Xe gas into the lungs, the 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate and wherein said inhalation delivering step comprises a breath-hold delivery period. - View Dependent Claims (4)
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7. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, wherein said delivering step comprises inhalation of the polarized 129Xe gas into the lungs, the 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate, and wherein the repetition time is decreased to emphasize a signal associated with capillaries in the pulmonary region.
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8. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, wherein said delivering step comprises inhalation of the polarized 129Xe gas into the lungs, the 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate, and wherein the repetition time is increased to include distal vasculature relative to the pulmonary capillaries. - View Dependent Claims (10)
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9. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, wherein dissolved-phase 129Xe has an associated decay time constant (T1) corresponding to its polarization life and a transverse relaxation time in blood (T2*), and wherein for T2* greater than about 100 ms, said acquiring step employs one of EPI and RARE multi-echo imaging methods.
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11. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 29Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, and wherein cardiac gating is used so that said acquiring step is timed such that it is performed during slow blood flow periods.
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12. A method for MRI imaging the pulmonary and/or cardiac vasculature using dissolved-phase polarized 129Xe, comprising the steps of:
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delivering polarized 129Xe gas to a predetermined region of the patient'"'"'s body, the polarized gas having a dissolved imaging phase associated therewith;
exciting a predetermined region of the patient'"'"'s body having a portion of the dissolved phase polarized gas therein with at least one large flip angle RF excitation pulse; and
acquiring at least one MR image associated with the dissolved phase polarized gas after said exciting step, wherein said exciting step is repeated within a predetermined repetition time, the predetermined repetition time being less than the time it takes for a given volume of blood to move from the lungs to the heart, wherein said delivering step comprises inhalation of the polarized 129Xe gas into the lungs, the 129Xe having a gas phase resonance which is higher than the dissolved-phase resonance, wherein at least a portion of the polarized 129Xe gas enters into the pulmonary vasculature in a dissolved-phase, wherein at least a portion of the dissolved-phase polarized 129Xe then enters the blood stream with an associated perfusion rate, wherein the at least one image is a multi-echo image, and wherein the multi-echo imaging uses one of gradient recalled and RF recalled echoes.
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13. A method for evaluating the blood flow of a patient, comprising the steps of:
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positioning a subject in a MR spectroscopy system capable of detecting spectroscopic signals in a subject having a pulmonary vasculature;
delivering gaseous polarized 129Xe to the subject;
dissolving a portion of the gaseous polarized 129Xe into the pulmonary vasculature having an associated blood flow path;
exciting the dissolved portion of the 129Xe with an MR spectroscopy RF excitation pulse; and
evaluating blood flow of the patient based on a spectroscopic signal corresponding to the dissolved polarized 129Xe, wherein said evaluating step includes the step of exciting the dissolved 129Xe with a large angle RF excitation pulse, wherein the MR Spectroscopy System comprises a magnetic field operably associated therewith, and wherein the magnetic field strength is less than about 0.5 T. - View Dependent Claims (14)
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15. A method for quantitatively evaluating the blood flow rate of a subject, comprising the steps of:
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administering gaseous polarized 129Xe to a subject such that the gaseous polarized 129Xe enters the subject'"'"'s lungs;
transmitting at least one large flip angle RF excitation pulse to the 129Xe after it travels, dissolved, into the subject'"'"'s vasculature based on said administering step;
obtaining a first polarized dissolved 129Xe spectroscopic response signal based on said large flip angle pulse transmitting step, the first response signal having a signal strength associated therewith;
obtaining a second polarized dissolved 129Xe spectroscopic response signal based on said at least one large flip angle pulse transmitting step, the second response signal having a signal strength associated therewith, wherein said second polarized dissolved 129Xe response signal obtaining step is temporally spaced apart a time interval from said first dissolved response signal obtaining step;
monitoring the increase in signal strength of the dissolved polarized 129Xe response signal over time based on said first and second dissolved response signal obtaining steps;
transmitting a predetermined flip angle RF excitation pulse to the gaseous 129Xe residing in the lung void space based on said administering step;
obtaining a first polarized 129Xe gas spectroscopic response signal based on said predetermined flip angle gaseous excitation transmitting step;
comparing the polarized 129Xe gas response signal with the first and second dissolved polarized 129Xe response signals; and
evaluating the blood flow rate of the subject based on said comparing step. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for quantitatively evaluating the blood flow rate of a subject, comprising the steps of:
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administering gaseous polarized 129Xe to a subject such that the gaseous polarized 129Xe enters the subject'"'"'s lungs;
transmitting at least one large flip angle RF excitation pulse to the 129Xe after it travels, dissolved, into the subject'"'"'s vasculature based on said administering step;
obtaining a first polarized dissolved 129Xe spectroscopic response signal based on said large flip angle pulse transmitting step, the first response signal having a signal strength associated therewith;
obtaining a second polarized dissolved 129Xe spectroscopic response signal based on said at least one large flip angle pulse transmitting step, the second response signal having a signal strength associated therewith, wherein said second dissolved polarized 129Xe response signal obtaining step is temporally spaced apart a time interval from said first dissolved polarized 129Xe response signal obtaining step;
monitoring the increase in signal strength of the dissolved polarized 129Xe response signal over time based on said first and second dissolved response signal obtaining steps; and
evaluating the blood flow rate of the subject based on said monitoring step. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
transmitting a predetermined flip angle RF excitation pulse to the gaseous 129Xe residing in the lung void space based on said administering step;
obtaining a first polarized 129Xe gas spectroscopic response signal having an associated signal strength based on said predetermined flip angle gaseous excitation transmitting step;
comparing the polarized 129Xe gas phase response signal with the first and second dissolved 129Xe response signals; and
quantitatively determining the blood flow rate of the subject based on said comparing step.
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32. A method according to claim 29, further comprising the step of calculating the slope of a line corresponding to the dissolved polarized 129Xe signal intensity over pulse repetition time.
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33. A method according to claim 31, further comprising the step of mathematically dividing the slope with the value of the polarized 129Xe gas response signal strength generated in said gas phase obtaining step.
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34. A method according to claim 29, further comprising the step of generating a Magnetic Resonance image of the polarized 129Xe in the lungs of the subject subsequent to said administering step.
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35. A method according to claim 31, further comprising the step of identifying a lung volume representative of the subject'"'"'s lungs and using the identified lung volume in said blood flow rate determination step.
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36. A method according to claim 31, further comprising the step of normalizing the blood flow rate obtained in said determining step by taking into account the subject'"'"'s heart rate.
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37. A method according to claim 29, further comprising the step of evaluating the existence of perfusion deficiencies or abnormalities.
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38. A method for quantitatively evaluating perfusion abnormalities and/or the blood flow rate of a subject, comprising the steps of:
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administering gaseous polarized 129Xe to a subject such that the gaseous polarized 129Xe enters the subject'"'"'s lungs;
transmitting at least one large flip angle RF excitation pulse to the 129Xe after it travels, dissolved, into the subject'"'"'s vasculature based on said administering step;
obtaining a first polarized dissolved 129Xe spectroscopic response signal based on said large flip angle pulse transmitting step, the first response signal having a signal strength associated therewith;
obtaining a second polarized dissolved 129Xe spectroscopic response signal based on said at least one large flip angle pulse transmitting step, the second response signal having a signal strength associated therewith, wherein said second dissolved polarized 129Xe response signal obtaining step is temporally spaced apart a time interval from said first dissolved polarized 129Xe obtaining step;
monitoring the signal strength of the dissolved polarized 129Xe response signal over time based on said first and second dissolved polarized 129Xe response signal obtaining steps; and
evaluating at least one of perfusion function or blood flow in the blood flow path of the subject based on said monitoring step. - View Dependent Claims (39, 40, 41, 42, 43)
(a) identifying the presence or absence of cardiac ischemias or infarcts;
(b) identifying thrombi or plaques;
(c) determining therapeutic windows for administering heparin, vasodilators, antihypertensive agents, and calcium antagonists;
(d) evaluating the severity or existence of ischemias;
(e) evaluating therapies in the treatment of cerebral vasospasm;
(f) assessing ischemia in large tissue masses;
(g) assessing the relationship between blood metabolites and cerebral perfusion in cerebral ischemia for the diagnosis or treatment of Alzheimer'"'"'s disease;
(h) evaluating therapies for stroke, (i) evaluating risk factors for stroke (j) evaluating induced brain hypothermia on cerebral perfusion during neurosurgery for stroke (k) evaluating the effects of age on cerebral perfusion; and
(l) assessing the effect of narcotics, on the ischemic brain.
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44. A method for MRI imaging the pulmonary and/or cardiac vasculature using polarized 129Xe dissolved in the blood stream, comprising the steps of:
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administering gaseous polarized 129Xe to a subject such that the gaseous polarized 129Xe enters the subject'"'"'s lungs;
transmitting at least one large flip angle RF excitation pulse from an MR apparatus to a first quantity of the 129Xe after it travels, dissolved, into the subject'"'"'s vasculature based on said administering step;
substantially destroying the polarization of the 129Xe dissolved in the subject'"'"'s vasculature based on said first transmitting step;
delaying a predetermined period of time and then transmitting a second large flip angle RF excitation pulse from the MR apparatus to a second quantity of the 129Xe after it travels, dissolved, into the subject'"'"'s vasculature, wherein the predetermined time is sufficient to allow the uptake of the second quantity of polarized 129Xe into the vasculature based on said administering step;
obtaining first and second response signals for the polarized dissolved 129Xe based on the corresponding first and second transmitting steps, the first and second response signals each having a signal strength associated therewith;
transmitting a third RF excitation pulse from the MR apparatus to excite the 129Xe gas in the lung of the subject;
obtaining a third response signal corresponding to the third transmitting step; and
acquiring at least one MR image comprising data provided by said first and second obtaining steps associated with the dissolved polarized 129Xe in the vasculature and at least one MR image comprising data provided by said third obtaining step associated with the 129Xe in the lung, wherein the predetermined time between said first and second transmitting steps is defined as a pulse repetition time, wherein said pulse repetition time is less than about 3 seconds, and wherein the first, second, and third obtaining steps are carried out during a single imaging session. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52)
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Specification