In vivo NMR and MRI using injection delivery of laser-polarized xenon

Abstract

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo 129 Xe NMR͞MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold.

Nuclear Magnetic Resonance of Laser-Polarized Noble Gases in Molecules, Materials, and Organisms

“…[234,235] and Ref. The above model predicts that laser-polarized xenon could be delivered to certain tissues more efficiently by injection than by respiration [236]. For example, it was suggested that by assuming reasonable values for the parameters in Eq.…”

“…The feasibility of using injectable carriers of laser-polarized xenon to perform in vim NMR and MRI was demonstrated in living laboratory rats [236]. In each experiment of this work, ml cc of a saturated polarized xenon solution was prepared according to the procedure described in Section 8.…”

“…Figure 8.13: 12gXeMR images of a laser-polarized xenon/saline solution injected into the upper hind leg of a living rat [236]. Acquisitions beg& immediately following the injection at 1, 8, 15, 21, 27, and 45 s. Displayed image intensities were normalized to the second image.…”

Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

“…8.12). The surface coil was used to monitor 12gXeNMR signals from the rat's liver region, permitting the wash-in/washout dynamics of the xenon in (PPm) Figure 8.12: In vivo 129XeNMR spectrum obtained by summing the 7th through 12th acquisitions following the intravenous injection of a laser-polarized xenon/Intralipid solution [236]. The signals were detected with a surface coil placed over the rat's liver region.…”

Hyperpolarized3He microspheres as a novel vascular signal source for MRI

“…For these investigations, the gas is either dissolved in the blood via inhalation or predissolved in a biologically compatible liquid that is then injected. Xenon is 10 -100 times more soluble than helium in most of the previously investigated carriers (blood, saline, intralipid, and perfluorocarbon emulsions) (7)(8)(9)(10)(11)(12). In addition, 129 Xe experiences a wide range of chemical shifts in different solvents, which should be advantageous for both functional imaging and perfusion studies (13).…”