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MR technology

Research group 8.11

MR imaging and spectroscopy of hyperpolarized rare gases

Hyperpolarized rare gases (3He and 129Xe) are used in a wide variety of magnetic resonance imaging research (MRI). Initially, the production and use of hyperpolarized 129Xe were advanced at PTB in order to perform in vivo spectroscopy on dissolved 129Xe in the human brain. Further activities concern the absolute measurement of the flow velocity of respiratory gas in the human respiratory system.

In newer activities, the application of a 129Xe biosensor has been studied to deal with questions from the field of immunology. This work was honored within the scope of the BMBF Innovationswettbewerb Medizintechnik 2009. Currently, the kinetics of the host/guest relationship of hyperpolarized 129Xe with carrier substances is being investigated.

In cooperation with the "Biosignals" Department (8.2), intensive work is being carried out in the field of research of SQUID detection of free nuclear spin precession in ultra-low magnetic fields. Here, the simultaneous detection of the spin precession of two species (3He and 129Xe) allows a "clock comparison experiment" to be carried out so that influences from external magnetic field fluctuations can be eliminated and limits for standard model extension theories can be determined.

Examples

  • Production of hyperpolarized 129Xe and 3He

    At PTB, instruments which are adapted to the generation and application of nuclear-spin-polarized 129Xe and 3He [1,2] and which work according to the principle of optical spin-exchange pumping have been set up (and are being set up) for the different fields of application. The magnetization of 129Xe or 3He which can be achieved in this way is approx. 10,000 times larger than the equilibrium magnetization of the same gas in the high field and allows spatially resolved MR images in the high field as well as highly sensitive measurements in the low field to be carried out.

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  • Free spin precession of hyperpolarized rare gases in ultra-low magnetic fields

    The free spin precession of hyperpolarized rare gases in ultra-low magnetic fields (1 nT < B < 10 µT) of high homogeneity (as are available at PTB in the magnetically shielded rooms) shows interesting phenomena. At sufficiently low gas pressures (p < 100 mbar), transverse relaxation times of several hours are attainable [ 3]. Due to the high signal-to-noise ratio, these measurements are also suited to characterize magnetic fields [ 4].



    Setup and measurement of the free spin precession in an ultra-low magnetic field showing here a transverse relaxation time of 4,560 seconds for hyperpolarized 129Xe.

    By simultaneously measuring the spin precession of hyperpolarized 3He und 129Xe (stored in a glass bulb), a co-magnetometer can be realized which allows coupling effects of the nuclear spin to be separated from the magnetic field fluctuations with high sensitivity. With a measuring time of approx. two hours, a measurement uncertainty of the difference frequency of the 3He und 129Xe spin precession of 0.2 nHz was achieved [ 5]. This allowed to lower the existing upper limits for Lorentz invariance violation [ 6,7] and for the spin-dependent short-range interaction between nucleons to be lowered [ 8]. Currently, activities for the measurement of an electric dipole moment of the Xenon nuclear spin (Xe-EDM) are in preparation [ 9].

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  • Spectroscopy of hyperpolarized 129Xe in the human brain

    In contrast to helium, xenon does not only readily dissolve in blood and tissue but also overcomes the blood-brain barrier. Thus, 129Xe can be detected in the human head by MR spectroscopy shortly after hyperpolarized xenon gas has been inhaled. For this purpose, time series measurements [ 10] have been carried out which could be analyzed with the aid of a perfusion model. From these investigations it could be concluded that xenon, dissolved in gray matter, can be readily distinguished from xenon dissolved in white matter.

     
    Measurement of the signals from hyperpolarized 129Xe in the human brain (dots) after inhalation of the gas at the time t = 0. By comparison to theoretically calculated concentrations (lines), the origin of the two signals can be assigned.

    In spatially resolved spectroscopic measurements (so-called “CSI images”), it was, in addition, possible to detect further signals from hyperpolarized 129Xe from areas outside the brain [11].

     
    Spatially resolved MR spectroscopy of 129Xe in the human brain in a sagittal (top) coronal (middle) and axial (bottom) projection. The signal at 0 ppm (1st column) arises from the gaseous xenon in the Tedlar bag, whereas the other four signals come from xenon dissolved in the human head. The dominant signals at 193 ppm and 196 ppm come from the brain, whereas the signals at about 190 ppm and 201 ppm are detected outside the brain.

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  • Velocimetry of flowing hyperpolarized rare gases

    MR phase contrast measurement allows the velocity of flowing media to be determined absolutely in m/s. In preliminary tests, MR measurements with hyperpolarized 129Xe flowing in pipe systems showed very good agreement with theoretically calculated flow profiles. In addition, first velocity measurements of hyperpolarized 129Xe were performed in vivo in the human trachea [12].

     
    Coronal (left) and three axial (right) MR velocity maps of hyperpolarized 129Xe in a flow phantom which simulates the bifurcation of the human trachea into main bronchia.

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  • Imaging of the lung with 129Xe and 3He

    The best-known field of application of hyperpolarized rare gases is MR imaging of the inhaled gas in the lungs. From it, new medical conclusions can be obtained, as conventional MR imaging, which images the protons in the tissue, can only detect very weak signals from the lung tissue.
     


    In the proton image (left), hardly any signals from the lungs can be seen. In the 129 image (right), the gas inhaled in the lung can be seen. The image in the middle is a superposition of both images.


     

    Coronal (top) and axial (bottom) MR images of hyperpolarized 129Xe (red) and 3He (green) in the human lung, measured on a healthy volunteer.

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  • Investigation of the magnetic properties of glasses

    In the production and storage of hyperpolarized rare gases, the purity of the glasses used plays a decisive role. Paramagnetic or ferromagnetic impurities are particularly detrimental. In measurements performed in cooperation with the Opens external link in new window working group of Professor Heil from Mainz University, it could be shown that ferromagnetic impurities can be found even in very pure glasses [13].

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Ausgewählte Literatur

  1. Wolfgang Kilian
    Erzeugung von hyperpolarisiertem 129-Xe-Gas und Nachweis mittles in vivo NMR-Bildgebung, NMR-Spektroskopie sowie SQUID-Messtechnik
    Erzeugung von hyperpolarisiertem 129-Xe-Gas und Nachweis mittles in vivo NMR-Bildgebung, NMR-Spektroskopie sowie SQUID-Messtechnik ; Berlin, Freie Univ., Diss., 2001, (2001), 1 - 136
    http://www.diss.fu-berlin.de/2001/105/

  2. Sergey E. Korchak, Wolfgang Kilian, Lorenz Mitschang
    Configuration and performance of a mobile 129Xe polarizer
    Applied Magnetic Resonance, 44, (2013), 1-2 [open access], 65 - 80
    http://dx.doi.org/10.1007/s00723-012-0425-7

  3. Wolfgang Kilian, Andreas Haller, Frank Seifert, Dirk Grosenick, Herbert Rinneberg
    Free precession and transverse relaxation of hyperpolarized 129Xe gas detected by SQUIDs in ultra-low magnetic fields
    The European Physical Journal D, 42, (2007), 2, 197 - 202
    http://dx.doi.org/10.1140/epjd/e2007-00026-8
    Download manuscript

  4. Martin Burghoff, Stefan Hartwig, Wolfgang Kilian, A. Vorwerk, Lutz Trahms
    SQUID systems adapted to record nuclear magnetism in low magnetic fields
    IEEE Transactions on Applied Superconductivity, 17, (2007), 2, 846 - 849
    http://dx.doi.org/10.1109/TASC.2007.898203

  5. C. Gemmel, W. Heil, S. Karpuk, K. Lenz, Ch. Ludwig, Yu. Sobolev, K. Tullney, Martin Burghoff, Wolfgang Kilian, Silvia Knappe-Grüneberg, Wolfgang Müller, Allard Schnabel, Frank Seifert, Lutz Trahms, St. Baeßler
    Ultra-sensitive magnetometry based on free precession of nuclear spins
    European Physical Journal D, 57, (2010), 3, 303 - 320
    http://dx.doi.org/10.1140/epjd/e2010-00044-5

  6. C. Gemmel, W. Heil, S. Karpuk, K Lenz, Yu. Sobolev, K Tullney, Martin Burghoff, Wolfgang Kilian, Silvia Knappe-Grüneberg, Wolfgang Müller, Allard Schnabel, Frank Seifert, Lutz Trahms, U. Schmidt
    Limit on Lorentz and CPT violation of the bound neutron using a free precession 3He/129Xe comagnetometer
    Physical Review D, 82, (2010), 11, 111901-1 - 111901-5
    http://dx.doi.org/10.1103/PhysRevD.82.111901

  7. F. Allmendinger, W. Heil, S. Karpuk, Wolfgang Kilian, A. Scharth, U. Schmidt, Allard Schnabel, Yu. Sobolev, K. Tullney
    New limit on Lorentz-invariance- and CPT-violating neutron spin interactions using a free-spin-precession 3He-129XE comagnetometer
    Physical Review Letters, 112, (2014), 11 [online first], 110801-1 - 110801-5
    http://dx.doi.org/10.1103/PhysRevLett.112.110801

  8. K. Tullney, F. Allmendinger, Martin Burghoff, W. Heil, S. Karpuk, Wolfgang Kilian, Silvia Knappe-Grüneberg, Wolfgang Müller, U. Schmidt, Allard Schnabel, Frank Seifert, Yu. Sobolev, Lutz Trahms
    Constraints on spin-dependent short-range interaction between nucleons
    Physical Review Letters, 111, (2013), 10, 100801-1 - 100801-5
    http://dx.doi.org/10.1103/PhysRevLett.111.100801
    http://link.aps.org/doi/10.1103/PhysRevLett.111.100801

  9. F. Kuchler, E. Babcock, Martin Burghoff, T. Chupp, S. Degenkolb, Isaac Fan, P. Fierlinger, F. Gong, E. Kraegeloh, Wolfgang Kilian, Silvia Knappe-Grüneberg, T. Lins, M. Marino, J. Meinel, B. Niessen, N. Sachdeva, Z. Salhi, Allard Schnabel, Frank Seifert, J. Singh, S. Stuiber, Lutz Trahms, Jens Voigt
    A new search for the atomic EDM of 129Xe at FRM-II
    Proceedings of the 6th International Symposium on Symmetries in Subatomic Physics (SSP 2015), Victoria, Canada, 8-12 June 2015 ; In: Hyperfine Interactions, 237, (2016), 12, 95 - 100
    http://dx.doi.org/10.1007/s10751-016-1302-9

  10. Wolfgang Kilian, Frank Seifert, Herbert Rinneberg
    Dynamic NMR spectroscopy of hyperpolarized 129Xe in human brain analyzed by an uptake model
    Magnetic Resonance in Medicine, 51, (2004), 4, 843 - 847
    http://dx.doi.org/10.1002/mrm.10726
    Download manuscript

  11. Frank Seifert, Wolfgang Kilian
    2D chemical shift imaging of hyperpolarized isotopically enriched 129Xe within human brain [poster]
    Proceedings ISMRM, (2005), [CD-ROM] file name: index SMART, 1163
    Download manuscript

  12. Wolfgang [speaker] Kilian, Max Strowig, Frank Seifert
    Velocimetry of hyperpolarized rare gases: phantom studies and first in vivo results [poster]
    Proceedings, ISMRM 14th scientific meeting : Seattle, Washington, USA, 6 - 12 May 2006, 14, (2006), [CD-ROM] file-name: 1325.pdf
    Download manuscript

  13. J. Schmiedeskamp, H.-J. Elmers, W. Heil, E.W. Otten, Yu. Sobolev, Wolfgang Kilian, Herbert Rinneberg, Tilmann Sander-Thömmes, Frank Seifert, J. Zimmer
    Relaxation of spin polarized 3He by magnetized ferromagnetic contaminants: Part III
    The European Physical Journal D, 38, (2006), 3, 445 - 454
    http://dx.doi.org/10.1140/epjd/e2006-00052-0
    Download manuscript

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