Heterogeneous Parahydrogen-Induced Polarization of Diethyl Ether for Magnetic Resonance Imaging Applications

Abstract

Magnetic resonance imaging (MRI) with the use of hyperpolarized gases as contrast agents provides valuable information on lungs structure and function. While the technology of ¹²⁹ Xe hyperpolarization for clinical MRI research is well developed, it requires the expensive equipment for production and detection of hyperpolarized ¹²⁹ Xe. Herein we present the ¹ H hyperpolarization of diethyl ether vapor that can be imaged on any clinical MRI scanner. ¹ H nuclear spin polarization of up to 1.3 % was achieved using heterogeneous hydrogenation of ethyl vinyl ether with parahydrogen over Rh/TiO₂ catalyst. Liquefaction of diethyl ether vapor proceeds with partial preservation of hyperpolarization and prolongs its lifetime by ≈10 times. The proof-of-principle 2D ¹ H MRI of hyperpolarized diethyl ether was demonstrated with 0.1×1.1 mm² spatial and 120 ms temporal resolution. The long history of use of diethyl ether for anesthesia is expected to facilitate the clinical translation of the presented approach.

Keywords: NMR spectroscopy; diethyl ether; hyperpolarization; imaging agents; parahydrogen-induced polarization.