NMR of laser-polarized xenon in human blood

Abstract

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude. The enhanced polarization has allowed advances in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), including polarization transfer to molecules and imaging of lungs and other void spaces. A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization. Described herein is an efficient method for the introduction of laser-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR͞MRI signals. Using this method, we have made the first observation of the timeresolved process of xenon penetrating the red blood cells in fresh human blood-the xenon residence time constant in the red blood cells was measured to be 20.4 ؎ 2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR͞MRI is discussed in light of their respective relaxation and partitioning properties.

High resolution spectroscopy and chemical shift imaging of hyperpolarized 129Xe dissolved in the human brain in vivo at 1.5 tesla

“…These earlier studies suggested the following peak assignments: 187.2 ppm, muscle 19, 20, 21; 192.7 ppm, white matter (and soft‐tissue in this study) 18, 19, 20, 21; 195.6 ppm, gray matter 18, 19, 20, 21; 199.6 ppm, aqueous solution (cerebrospinal fluid, plasma, and interstitial fluid in this study) 10, 11, 24, 25, 26 and fat/lipid tissue outside the brain 19, 20; and 217.2 ppm, red blood cells 4, 10, 24, 26.…”

Large Production System for Hyperpolarized 129Xe for Human Lung Imaging Studies

“…129 Xe displays an NMR spectrum with chemical shifts in resonance frequency that characterize its microscopic/molecular environment [14,15]. It offers longitudinal magnetization that survives several seconds to several tens of seconds in vivo [16,17]. The time and spatial dependence of its distribution in the body can reveal functional attributes [18,19].…”

Xe NMR lineshapes in channels of peptide molecular crystals

“…The Xe atom has a large electric dipole polarizability; cavities within proteins are about the correct size to hold one or more Xe atoms, and the unfavorable entropic term related to the need to orient the ligand in the binding site is absent for Xe atom. The affinity of Xe for hydrophobic cavities in the interiors of macromolecules (5)(6)(7)(8)(9)(10) coupled with the development of techniques for hyperpolarization of Xe nuclear spins have inspired an array of NMR studies of Xe in proteins (11), cells, (12,13), and tissues (14)(15)(16). For example, hyperpolarized (HP) 129 Xe has been developed as a tool for the characterization of protein cavities which bind Xe, by using its nuclear spin polarization to enhance the signals of the protons in the cavity (10,17), by using the Xe chemical shift itself as a reporter of cavity structure in both solution and the solid state (11), and in applications to biomolecular assays (18,19).…”