| Zugriffsnummer | 20145 |
| Dokumenttyp | Konferenzartikel |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | Hyperpolarized 129Xe gas: SQUID detection of nuclear spin precession in low magnetic fields [poster] |
| Autor(in); Institution |
Rinneberg, Herbert; 8, Medizinphysik und metrologische Informationstechnik, PTB-Berlin
Kilian, Wolfgang; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Haller, Andreas; 8.21, Bioelektrizität und -magnetismus, PTB-Berlin
Schubert, Florian; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Grosenick, Dirk; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Wübbeler, Gerd; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Seifert, Frank; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Trahms, Lutz; 8.21, Bioelektrizität und -magnetismus, PTB-Berlin
|
| Quelle/Jahr | Proceedings of the 12th International Conference on Biomagnetism: August 13 - 17, 2000, Helsinki University of Technology, Espoo, Finland:(2000), 222 |
| ISBN | 951-22-5401-8 |
| Verlag | Espoo: Helsinki Univ. of Technology |
| Konferenzangaben | 12th International Conference on Biomagnetism (Helsinki University of Technology), Espoo, 13.-17. August , 2000, Finland |
| Zusammenfassung | Introduction Hyperpolarized noble gases (3He, 129Xe) have been successfully used in NMR tomography for lung imaging and perfusion measurements. Detection of magnetization of hyperpolarized xenon in low magnetic fields by SQUIDs could offer possibilities for in vivo relaxometry. Methods: Hyperpolarized 129Xe was produced off-line by spin-exchange optical pumping of Rb vapor using circularly polarized laser radiation. Free precession of the nuclear magnetization of the hyperpolarized xenon gas (natural abundance of 129Xe: 26%) contained in a spherical glass bulb (Ø 5 cm) was recorded by a single channel dc SQUID gradiometer inside a magnetically shielded room (BMSR). In addition, a 37 channel dc SQUID agnetometer system was used to measure the spatial distribution of the magnetic field produced by the precessing nuclear magnetization. Results and Discussion The free precession of the 129Xe nuclear magnetization induced field amplitudes of up to 40 pT peak-to-peak. Larmor periods as long as 18 s were recorded corresponding to an ambient magnetic field strength of 4.5 nT. Transverse relaxation times up to T2 » 8000 s were observed. The pressure and magnetic field dependence (40-900 mbar, 4.5 nT, 15 nT) of T2 was measured and found to be consistent with relaxation caused by diffusion of xenon atoms in magnetic field gradients. Adding oxygen to the xenon gas dramatically shortened the relaxation time to T2 » 30 s (12 vol% O2 / 21 vol% Xe / 67 vol% N2). The precessing spatial magnetic field distribution measured by the 37 channel SQUID system could be quantitatively analyzed, assuming a precessing magnetic dipole at the center of the sphere. In this way, the location of the sphere and the component of the magnetization perpendicular to the (ambient) magnetic field were determined. Due to the long transverse relaxation times observed it is conceivable that hyperpolarized noble gases can be used for spatially resolved biomagnetic relaxometry employing multi-channel SQUID systems. |
Zitierung
Rinneberg, H., Kilian, W., Haller, A., Schubert, F., Grosenick, D., Wübbeler, G., Seifert, F., & Trahms, L. (2000). Hyperpolarized ¹²⁹Xe gas: SQUID detection of nuclear spin precession in low magnetic fields [poster]. 12th International Conference on Biomagnetism (Helsinki University of Technology), Espoo, 13.-17. August , 2000, Finland.