Xenon gas MRI

Last updated

Hyperpolarized 129Xe gas magnetic resonance imaging (MRI) is a medical imaging technique used to visualize the anatomy and physiology of body regions that are difficult to image with standard proton MRI. In particular, the lung, which lacks substantial density of protons, is particularly useful to be visualized with 129Xe gas MRI. This technique has promise as an early-detection technology for chronic lung diseases and imaging technique for processes and structures reliant on dissolved gases. [1] [2] 129Xe is a stable, naturally occurring isotope of xenon with 26.44% isotope abundance. It is one of two Xe isotopes, along with 131Xe, that has non-zero spin, which allows for magnetic resonance. 129Xe is used for MRI because its large electron cloud permits hyperpolarization and a wide range of chemical shifts. The hyperpolarization creates a large signal intensity, and the wide range of chemical shifts allows for identifying when the 129Xe associates with molecules like hemoglobin. 129Xe is preferred over 131Xe for MRI because 129Xe has spin 1/2 (compared to 3/2 for 131Xe), a longer T1, and 3.4 times larger gyromagnetic ratio (11.78 MHz/T). [3]

Contents

Uses

Medical uses

Xenon Xe 129 hyperpolarized
Clinical data
Trade names Xenoview
License data
Routes of
administration 		Inhalation
ATC code
  • None
Legal status
Legal status
Identifiers
CAS Number
PubChem CID
UNII
KEGG

Xenon Xe 129 hyperpolarized, sold under the brand name Xenoview, is a hyperpolarized contrast agent indicated for use with magnetic resonance imaging (MRI) for evaluation of lung ventilation, and approved for people aged twelve years of age and older. [4] [5] It was approved for medical use in the US in December 2022. [6]

The most common side effects include mouth and throat pain, headache, and dizziness. [5]

The US Food and Drug Administration (FDA) considers it to be a first-in-class medication. [7] [8]

The FDA approved Xenoview based on evidence from two clinical trials in 83 participants with various lung disorders who were being evaluated for possible lung resection or lung transplantation. [5] The trials were conducted at five sites in the United States and assessed both efficacy and safety of Xenoview. [5] Xenoview was evaluated in two clinical trials of 83 adults with pulmonary disorders who each underwent sequential lung ventilation imaging with Xenoview with MRI and an approved comparator, Xe 133 scintigraphy. [5] In study 1, participants were imaged to help plan possible lung resection. [5] To determine the benefit of Xenoview, estimates of the percentage of lung ventilation predicted to remain after surgery made with Xenoview with MRI and comparator imaging were evaluated for equivalence. [5] In study 2, participants were imaged to help plan possible lung transplantation. [5] To determine the benefit of Xenoview, estimates of the percentage of lung ventilation contributed by the right lung made with Xenoview with MRI and comparator imaging were evaluated for equivalence. [5]

History

Hyperpolarized 129Xe is achieved through spin-exchange optical pumping, a technique developed by Grover et al. in 1978 [9] and improved by Happer et al. in 1984. [10] Quantification of 129Xe polarization was first described in 1982 by Bhaskar et al. [11] The use of hyperpolarized 129Xe gas in MRI ex-vivo was first described by Albert et al. in 1994 using excised rat lungs. [12] The first in-vivo human studies with 129Xe MRI were published by Mugler et al. in 1997. [13]

129Xe MRI has largely begun to replace 3He gas MRI, a very similar technology that uses hyperpolarized 3He molecules instead of 129Xe. Grossman et al. began human clinical trials for 3He MRI in 1996. 3He was originally touted as the better gas for hyperpolarized gas MRI because it is more polarizable and has no effects on the body. [1] However, 3He is mostly produced by the beta decay of tritium (3H), which is a product of nuclear warhead production. Additionally, 3He is widely used by the U.S. military to detect smuggled plutonium. [14] These combination of increasing scarcity and increasing demand have combined to make 3He highly expensive, up to more than $1000 per liter. [15]

Safety

129Xe is an inert, non-radioactive, non-toxic, and non-teratogenic molecule that has shown no significant adverse health effects when inhaled for MR imaging. [16] [17] One potential area of concern is 129Xe's anesthetic properties when a large volume is inhaled. Xenon shows blood and tissue solubility [16] that allows it to diffuse through the lung membrane and affect the nervous system. The minimum alveolar concentration for 50% of motor response to be prevented (MAC) is 0.71, which is not reached during imaging. [16] Further studies have shown that it provides good circulatory stability when dissolved in blood and does not affect body temperature. [18]

Hyperpolarization

When applying an external magnetic field to gas, half of the nuclear spins of the gas atoms point towards the direction of the magnetic field whereas the other half point in the opposite direction. It is slightly more energetically favorable to be aligned with the magnetic field, meaning that one of the spin states is in slight excess of the other. This excess means that the two spin-states do not completely cancel each other out, creating a magnetic signal which can be observed with MRI. However, for traditional 1H MRI, only about 4 ppm of the spin states do not cancel, so the signal is not particularly strong. This means that only regions with high densities of protons, like muscle tissue can be seen. [1] Hyperpolarization is a means of flipping more of the atoms to have the same spin state so that less of the spin states cancel each other. In the case of 129Xe, this leads to a 104-105 improvement in signal strength. [1]

Polarization Transfer Polarization Transfer.jpg
Polarization Transfer

Hyperpolarization of 129Xe is usually performed using spin-exchange optical pumping (SEOP) using circularly polarized light to add angular momentum of the atoms. However, the polarized light cannot directly transfer angular momentum to the gas nuclei, thus, an alkali metal atom is used as an intermediary. [1] [16] Rubidium is often used to accomplish this, where the polarized light is tuned to provide exactly the necessary energy to excite rubidium's valence electron. This process is called optical pumping. In the next step, spin exchange, gas nuclei are introduced to the system and collide with the rubidium. They receive angular momentum in the collisions with rubidium valence electrons, which, by conservation of angular momentum, is in the same direction as the rubidium. Therefore, 129Xe becomes hyperpolarized because there is a large excess of one spin state compared to the other. After this, the 129Xe is extracted, the rubidium is polarized again, and the cycle continues. [1] [16]

Required modifications to conventional MRI

Traditional MR scanners need to be modified to detect 129Xe, as 129Xe has a lower gyromagnetic ratio of 11.77 MHz/T compared to that of protons, 42.5 MHz/T. Thus, the Larmor frequency of 129Xe is much lower, which is difficult to detect with conventional narrow-band RF amplifiers set to proton's Larmor frequency. Therefore, a broad-band RF amplifier, for both excitation and receiving, is required. [1] Additionally, the pulse sequence must also accommodate the difference in thermally-polarized protons and polarized 129Xe. [1] [19] In proton MRI, a typical pulse sequence would involve a 90° flip then a subsequent T1 longitudinal relaxation to the external magnetic field. T1 relaxation in hyperpolarized gas involves the decay of magnetization and not the return to an external magnetic field, as in thermally-polarized protons. [19] Therefore, after a 90° flip, a hyperpolarized gas nuclei's longitudinal relaxation is negligible, making the longitudinal magnetization remain zero after the flip. As a result, traditional 90° and 180° RF pulses are not desirable. [1] [19] A low-angle RF pulse is therefore used to only remove a portion of the total available magnetization of the hyperpolarized 129Xe gas. This produces comparable longitudinal magnetization between protons and 129Xe gas. [19] Furthermore, as an image needs to be acquired within a breath-hold, a fast pulse-sequences, or fast-gradient echos, are used to adequately sample the k-space. [1] [19]

Applications

Ventilation MRI

After a patient inhales the hyperpolarized gas, the gas passes through the airways within the lungs. In a healthy lung, the gas is able to travel throughout the lungs. However, in a disease that obstructs airways, such as chronic obstructive pulmonary disease (COPD), asthma, and cystic fibrosis, the hyperpolarized gas is unable to reach certain regions within the lung. [1] [19] [20] Thus, a spin-density weighted image will produce high signals from normal areas and low signals from diseased regions. 3He was originally used for this type of image, but recently there has been a shift towards to 129Xe due to its availability and cheaper price. [20] Hyperpolarized 3He has historically produced superior images because it is easier to hyperpolarize, but current technology has improved gas polarization of 129Xe to the point where the image quality is similar. Furthermore, 129Xe is more sensitive to obstructions as it is a larger atom than 3He. In addition, an increased inhaled volume of 129Xe results in a comparable SNR to that of 3He, up to 1 vs 0.1-0.3 liters. [1]

Diffusion MRI

Diffusion MRI involves calculating the apparent diffusion coefficient (ADC) of the hyperpolarized gas. Diffusion-sensitizing gradients are applied to induce diffusion based attenuation to calculate the ADC. [1] [19] These gradients have an associated b-value, which represents the strength and duration of the gradients. At least 2 different b-value gradients are used to calculate the ADC. The ADC provides information regarding how the structure of the lung restricts the hyperpolarized gas diffusion. [19] The value of the ADC increases in regions of increased space. For example, in healthy lungs, the ADC using 129Xe might be around 0.04 cm2/s whereas the ADC for 129Xe in an open space may be around 0.14 cm2/s. [19] In emphysema, where alveolar structures enlarge, the gas is able to diffuse more freely, resulting in a higher ADC compared to normal regions providing information of disease areas. [1] [19] Ultimately, this is a novel imaging modality enabled by 129Xe MRI, and its use is being investigated for Chronic Obstructive Pulmonary Disease, Asthma, Cystic Fibrosis, Long-COVID-19, and other diseases.

Partial pressure of oxygen

The longitudinal relaxation (T1) of the hyperpolarized gas is inversely proportional to the concentration of the oxygen in the lung. [19] The interaction between paramagnetic oxygen significantly decreases the relaxation time, which offers insights into the partial pressure of oxygen (pO2) within regions of the lung. Additionally, the ventilation to perfusion ratio can be calculated from these images. [21] Most research has employed 3He, but improved technology has allowed for comparable results when using 129Xe. However, due to the uptake of 129Xe, its relaxation is much quicker than 3He resulting in higher apparent pO2 if left unaccounted. [19]

Research

Xe Gas MRI of Healthy and Diseased Lungs. Colors show different intensities of Xe Gas. Xe Gas MRI of Healthy and Diseased Lungs.png
Xe Gas MRI of Healthy and Diseased Lungs. Colors show different intensities of Xe Gas.

129Xe gas MRI is being researched as a diagnostic test for respiratory diseases, such as COPD, asthma, and emphysema. Spirometry pulmonary function tests are used to determine the condition of lung function. [22] However, this is a fairly basic, global assessment of lung function that does not provide specific information about the lung structure and physiology. For structural information, X-Ray CT is most commonly used, but it exposes the patient to high doses of ionizing radiation and it provides no functional information [23] Conventional 1H MRI is not effective in the lung airspace because of the minimal proton density. 129Xe gas MRI provides detailed, specific information about lung structure and function that are not safely or efficiently obtainable by existing technologies. [1]

Visualizing non-lung tissues

129Xe gas is most commonly used to visualize the lung because it is a gas. However, small bubbles of xenon gas are capable of dissolving into the bloodstream at the alveoli. As these bubbles travel around the body, they can be used to gain insight into other regions of the body. 129Xe gas is capable of crossing the blood brain barrier, allowing novel study of brain perfusion.r [2]

Improving amount of hyperpolarization

Using hyperpolarized gas to image the lungs is not particularly novel, as the use of 3He was established in the early 2000s. [24] 3He was originally chosen because it was easily hyperpolarized to a very large degree, and therefore generated a very strong signal. Recently, improvements in hyperpolarization techniques have been able to generate more hyperpolarized 129Xe, enabling it to generate comparable images to 3He.

Related Research Articles

Helium-3 is a light, stable isotope of helium with two protons and one neutron. Other than protium, helium-3 is the only stable isotope of any element with more protons than neutrons. It was discovered in 1939.

<span class="mw-page-title-main">Magnetic resonance imaging</span> Medical imaging technique

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy.

<span class="mw-page-title-main">Noble gas</span> Group of low-reactive, gaseous chemical elements

The noble gases are the naturally occurring members of group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Under standard conditions, these elements are odorless, colorless, monatomic gases with very low chemical reactivity and cryogenic boiling points.

<span class="mw-page-title-main">Xenon</span> Chemical element with atomic number 54 (Xe)

Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.

Hyperpolarization is the nuclear spin polarization of a material in a magnetic field far beyond thermal equilibrium conditions determined by the Boltzmann distribution. It can be applied to gases such as 129Xe and 3He, and small molecules where the polarization levels can be enhanced by a factor of 104-105 above thermal equilibrium levels. Hyperpolarized noble gases are typically used in magnetic resonance imaging (MRI) of the lungs. Hyperpolarized small molecules are typically used for in vivo metabolic imaging. For example, a hyperpolarized metabolite can be injected into animals or patients and the metabolic conversion can be tracked in real-time. Other applications include determining the function of the neutron spin-structures by scattering polarized electrons from a very polarized target (3He), surface interaction studies, and neutron polarizing experiments.

Naturally occurring xenon (54Xe) consists of seven stable isotopes and two very long-lived isotopes. Double electron capture has been observed in 124Xe and double beta decay in 136Xe, which are among the longest measured half-lives of all nuclides. The isotopes 126Xe and 134Xe are also predicted to undergo double beta decay, but this process has never been observed in these isotopes, so they are considered to be stable. Beyond these stable forms, 32 artificial unstable isotopes and various isomers have been studied, the longest-lived of which is 127Xe with a half-life of 36.345 days. All other isotopes have half-lives less than 12 days, most less than 20 hours. The shortest-lived isotope, 108Xe, has a half-life of 58 μs, and is the heaviest known nuclide with equal numbers of protons and neutrons. Of known isomers, the longest-lived is 131mXe with a half-life of 11.934 days. 129Xe is produced by beta decay of 129I ; 131mXe, 133Xe, 133mXe, and 135Xe are some of the fission products of both 235U and 239Pu, so are used as indicators of nuclear explosions.

Carbon-13 (C13) nuclear magnetic resonance is the application of nuclear magnetic resonance (NMR) spectroscopy to carbon. It is analogous to proton NMR and allows the identification of carbon atoms in an organic molecule just as proton NMR identifies hydrogen atoms. 13C NMR detects only the 13
C
 isotope. The main carbon isotope, 12
C
 does not produce an NMR signal. Although ca. 1 mln. times less sensitive than 1H NMR spectroscopy, 13C NMR spectroscopy is widely used for characterizing organic and organometallic compounds, primarily because 1H-decoupled 13C-NMR spectra are more simple, have a greater sensitivity to differences in the chemical structure, and, thus, are better suited for identifying molecules in complex mixtures. At the same time, such spectra lack quantitative information about the atomic ratios of different types of carbon nuclei, because nuclear Overhauser effect used in 1H-decoupled 13C-NMR spectroscopy enhances the signals from carbon atoms with a larger number of hydrogen atoms attached to them more than from carbon atoms with a smaller number of H's, and because full relaxation of 13C nuclei is usually not attained, and the nuclei with shorter relaxation times produce more intense signals.

<span class="mw-page-title-main">Molecular imaging</span> Imaging molecules within living patients

Molecular imaging is a field of medical imaging that focuses on imaging molecules of medical interest within living patients. This is in contrast to conventional methods for obtaining molecular information from preserved tissue samples, such as histology. Molecules of interest may be either ones produced naturally by the body, or synthetic molecules produced in a laboratory and injected into a patient by a doctor. The most common example of molecular imaging used clinically today is to inject a contrast agent into a patient's bloodstream and to use an imaging modality to track its movement in the body. Molecular imaging originated from the field of radiology from a need to better understand fundamental molecular processes inside organisms in a noninvasive manner.

<span class="mw-page-title-main">Gadopentetic acid</span> Complex of gadolinium by DTPA

Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent.

<span class="mw-page-title-main">Krypton</span> Chemical element with atomic number 36 (Kr)

Krypton is a chemical element; it has symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. Krypton is chemically inert.

During nuclear magnetic resonance observations, spin–lattice relaxation is the mechanism by which the longitudinal component of the total nuclear magnetic moment vector (parallel to the constant magnetic field) exponentially relaxes from a higher energy, non-equilibrium state to thermodynamic equilibrium with its surroundings (the "lattice"). It is characterized by the spin–lattice relaxation time, a time constant known as T1.

Magnetic resonance spectroscopic imaging (MRSI) is a noninvasive imaging method that provides spectroscopic information in addition to the image that is generated by MRI alone.

<span class="mw-page-title-main">Nuclear magnetic resonance</span> Spectroscopic technique based on change of nuclear spin state

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. High-resolution nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI). The original application of NMR to condensed matter physics is nowadays mostly devoted to strongly correlated electron systems. It reveals large many-body couplings by fast broadband detection and should not be confused with solid state NMR, which aims at removing the effect of the same couplings by Magic Angle Spinning techniques.

<span class="mw-page-title-main">Physics of magnetic resonance imaging</span> Overview article

Magnetic resonance imaging (MRI) is a medical imaging technique mostly used in radiology and nuclear medicine in order to investigate the anatomy and physiology of the body, and to detect pathologies including tumors, inflammation, neurological conditions such as stroke, disorders of muscles and joints, and abnormalities in the heart and blood vessels among others. Contrast agents may be injected intravenously or into a joint to enhance the image and facilitate diagnosis. Unlike CT and X-ray, MRI uses no ionizing radiation and is, therefore, a safe procedure suitable for diagnosis in children and repeated runs. Patients with specific non-ferromagnetic metal implants, cochlear implants, and cardiac pacemakers nowadays may also have an MRI in spite of effects of the strong magnetic fields. This does not apply on older devices, and details for medical professionals are provided by the device's manufacturer.

The polarized targets are used as fixed targets in scattering experiments. In high energy physics they are used to study the nucleon spin structure of simple nucleons like protons, neutrons or deuterons. In deep inelastic scattering the hadron structure is probed with electrons, muons or neutrinos. Using a polarized high energy muon beam, for example, on a fixed target with polarized nucleons it is possible to probe the spin dependent part of the structure functions.

In respiratory physiology, specific ventilation is defined as the ratio of the volume of gas entering a region of the lung (ΔV) following an inspiration, divided by the end-expiratory volume (V0) of that same lung region:

Hyperpolarized carbon-13 MRI is a functional medical imaging technique for probing perfusion and metabolism using injected substrates.

<span class="mw-page-title-main">MRI pulse sequence</span>

An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance.

Hyperpolarized gas MRI, also known as hyperpolarized helium-3 MRI or HPHe-3 MRI, is a medical imaging technique that uses hyperpolarized gases to improve the sensitivity and spatial resolution of magnetic resonance imaging (MRI). This technique has many potential applications in medicine, including the imaging of the lungs and other areas of the body with low tissue density.

Xin Zhou is a Chinese scientist specializing in magnetic resonance imaging. He holds the position of Professor and currently serves as the President of the Innovation Academy for Precision Measurement Science and Technology (APM) at the Chinese Academy of Sciences since July 2022.APM comprises two state key laboratories: the State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, and the State Key Laboratory of Geodesy and Earth's Dynamics. Additionally, it hosts several national platforms, including the National Center for Magnetic Resonance in Wuhan.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Roos JE, McAdams HP, Kaushik SS, Driehuys B (May 2015). "Hyperpolarized Gas MR Imaging: Technique and Applications". Magnetic Resonance Imaging Clinics of North America. 23 (2): 217–229. doi:10.1016/j.mric.2015.01.003. PMC   4428591 . PMID   25952516.
  2. 1 2 Rao MR, Stewart NJ, Griffiths PD, Norquay G, Wild JM (February 2018). "Imaging Human Brain Perfusion with Inhaled Hyperpolarized 129Xe MR Imaging". Radiology. 286 (2): 659–665. doi: 10.1148/radiol.2017162881 . PMID   28858563.
  3. ↑ Oros AM, Shah NJ (October 2004). "Hyperpolarized xenon in NMR and MRI" (PDF). Physics in Medicine and Biology. 49 (20): R105–R153. doi:10.1088/0031-9155/49/20/r01. PMID   15566166. S2CID   250857751. Archived (PDF) from the original on 27 December 2022. Retrieved 27 December 2022.
  4. 1 2 "Xenoview- xenon xe 129 hyperpolarized gas". DailyMed. 30 December 2022. Archived from the original on 21 January 2023. Retrieved 21 January 2023.
  5. 1 2 3 4 5 6 7 8 9 "Drug Trials Snapshots: Xenoview". U.S. Food and Drug Administration. 23 December 2022. Archived from the original on 20 December 2023. Retrieved 8 January 2024.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  6. ↑ "FDA Approves Polarean's Xenoview (xenon Xe 129 hyperpolarized) for use with MRI for the Evaluation of Lung Ventilation" (Press release). Polarean Imaging. 28 December 2022. Archived from the original on 31 August 2023. Retrieved 31 August 2023– via GlobeNewswire.
  7. ↑ "Advancing Health Through Innovation: New Drug Therapy Approvals 2022". U.S. Food and Drug Administration (FDA). 10 January 2023. Archived from the original on 21 January 2023. Retrieved 22 January 2023.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  8. ↑ New Drug Therapy Approvals 2022 (PDF). U.S. Food and Drug Administration (FDA) (Report). January 2024. Archived from the original on 14 January 2024. Retrieved 14 January 2024.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  9. ↑ Grover BC (6 February 1978). "Noble-Gas NMR Detection through Noble-Gas-Rubidium Hyperfine Contact Interaction". Physical Review Letters. 40 (6): 391–392. Bibcode:1978PhRvL..40..391G. doi:10.1103/PhysRevLett.40.391. ISSN   0031-9007.
  10. ↑ Happer W, Miron E, Schaefer S, Schreiber D, Van Wijngaarden WA, Zeng X (1 June 1984). "Polarization of the nuclear spins of noble-gas atoms by spin exchange with optically pumped alkali-metal atoms". Physical Review A. 29 (6): 3092–3110. Bibcode:1984PhRvA..29.3092H. doi:10.1103/PhysRevA.29.3092. ISSN   0556-2791. Archived from the original on 9 April 2023. Retrieved 5 December 2021.
  11. ↑ Bhaskar ND, Happer W, McClelland T (5 July 1982). "Efficiency of Spin Exchange between Rubidium Spins and Xe 129 Nuclei in a Gas". Physical Review Letters. 49 (1): 25–28. doi:10.1103/PhysRevLett.49.25. ISSN   0031-9007.
  12. ↑ Marshall H, Stewart NJ, Chan HF, Rao M, Norquay G, Wild JM (February 2021). "In vivo methods and applications of xenon-129 magnetic resonance". Progress in Nuclear Magnetic Resonance Spectroscopy. 122: 42–62. doi:10.1016/j.pnmrs.2020.11.002. PMC   7933823 . PMID   33632417.
  13. ↑ Mugler JP, Driehuys B, Brookeman JR, Cates GD, Berr SS, Bryant RG, et al. (June 1997). "MR imaging and spectroscopy using hyperpolarized 129Xe gas: preliminary human results". Magnetic Resonance in Medicine. 37 (6): 809–815. doi:10.1002/mrm.1910370602. PMID   9178229. S2CID   27232819.
  14. ↑ Albert MS, Balamore D (1998). "Development of hyperpolarized noble gas MRI". Nuclear Instruments and Methods in Physics Research Section A. 402 (2–3): 441–453. Bibcode:1998NIMPA.402..441A. doi:10.1016/s0168-9002(97)00888-7. PMID   11543065.
  15. ↑ Adee S (31 August 2010). "Physics Projects Deflate for Lack of Helium-3". IEEE Spectrum. Archived from the original on 6 December 2021. Retrieved 5 December 2021.
  16. 1 2 3 4 5 Kennedy RR, Stokes JW, Downing P (February 1992). "Anaesthesia and the 'inert' gases with special reference to xenon". Anaesthesia and Intensive Care. 20 (1): 66–70. doi: 10.1177/0310057X9202000113 . PMID   1319119. S2CID   29886337.
  17. ↑ Driehuys B, Martinez-Jimenez S, Cleveland ZI, Metz GM, Beaver DM, Nouls JC, et al. (January 2012). "Chronic obstructive pulmonary disease: safety and tolerability of hyperpolarized 129Xe MR imaging in healthy volunteers and patients". Radiology. 262 (1): 279–289. doi:10.1148/radiol.11102172. PMC   3244666 . PMID   22056683.
  18. ↑ Marx T, Schmidt M, Schirmer U, Reinelt H (October 2000). "Xenon anaesthesia". Journal of the Royal Society of Medicine. 93 (10): 513–517. doi:10.1177/014107680009301005. PMC   1298124 . PMID   11064688.
  19. 1 2 3 4 5 6 7 8 9 10 11 12 Mugler JP, Altes TA (February 2013). "Hyperpolarized 129Xe MRI of the human lung". Journal of Magnetic Resonance Imaging. 37 (2): 313–331. doi:10.1002/jmri.23844. PMC   3558952 . PMID   23355432.
  20. 1 2 Ebner L, Kammerman J, Driehuys B, Schiebler ML, Cadman RV, Fain SB (January 2017). "The role of hyperpolarized 129xenon in MR imaging of pulmonary function". European Journal of Radiology. 86: 343–352. doi:10.1016/j.ejrad.2016.09.015. PMC   5195899 . PMID   27707585.
  21. ↑ Rizi RR, Baumgardner JE, Ishii M, Spector ZZ, Edvinsson JM, Jalali A, et al. (July 2004). "Determination of regional VA/Q by hyperpolarized 3He MRI". Magnetic Resonance in Medicine. 52 (1): 65–72. doi: 10.1002/mrm.20136 . PMID   15236368. S2CID   25053184.
  22. ↑ Ranu H, Wilde M, Madden B (May 2011). "Pulmonary function tests". The Ulster Medical Journal. 80 (2): 84–90. PMC   3229853 . PMID   22347750.
  23. ↑ Zhu X, Yu J, Huang Z (September 2004). "Low-dose chest CT: optimizing radiation protection for patients". AJR. American Journal of Roentgenology. 183 (3): 809–816. doi:10.2214/ajr.183.3.1830809. PMID   15333374.
  24. ↑ van Beek EJ, Wild JM (1 December 2005). "Hyperpolarized 3-helium magnetic resonance imaging to probe lung function". Proceedings of the American Thoracic Society. 2 (6): 528–32, 510. doi:10.1513/pats.200507-071DS. PMID   16352759.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.