Parahydrogen Induced Polarization was employed to prepare nuclear singlet state between methylene and methyl protons in propane gas. Low-field MRI preserves this singlet state with much longer TS=4.7±0.5 s. Spin-Lock Induced Crossing (SLIC) transforms singlet state in observable nuclear magnetization suitable for MRI with sub-millimeter and sub-second spatial and temporal resolution respectively with signal enhancement>10,000 times. Long-lived spin states created in hyperpolarized propane-d6 gas can be detected directly at 0.0475 T. This long lifetime and non-toxic nature of propane gas could be useful for bio-imaging applications including potentially pulmonary low-field MRI. The feasibility of high-resolution low-field 2D gradient-echo MRI was demonstrated with 0.88×0.88 mm2 spatial and ˜0.7 s temporal resolution respectively at 0.0475 T. Propane is a non-toxic gas, and therefore, these results enable low-cost high-resolution high-speed MRI of gases for imaging of lungs.
