Rapid lung ventilation MRI using parahydrogen-induced polarization of propane gas

Abstract

Proton-hyperpolarized contrast agents are attractive because they can be imaged on virtually any clinical MRI scanner, which is typically equipped to scan only protons rather than heteronuclei (i.e., anything besides protons, e.g., ¹³C, ¹⁵N, ¹²⁹Xe, ²³Na, etc.). Even though the lifetime of the proton spin hyperpolarization is only a few seconds, it is sufficient for inhalation and scanning of proton-hyperpolarized gas media. We demonstrate the utility of producing hyperpolarized propane gas via heterogeneous parahydrogen-induced polarization for the purpose of ventilation imaging in an excised rabbit lung model. The magnetization of protons in hyperpolarized propane gas is similar to that of tissue water protons, making it possible to rapidly perform lung ventilation imaging with a 0.35 T clinical MRI scanner. Here, we demonstrate the feasibility of rapid (2 s) lung ventilation MRI in excised rabbit lungs using hyperpolarized propane gas with a 1 × 1 mm² pixel size using a 50 mm slice thickness, and a 1.7 × 1.7 mm² pixel size using a 9 mm slice thickness.