15N Hyperpolarization by Reversible Exchange Using SABRE-SHEATH

NMR signal amplification by reversible ex, change (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target, substrate and parahydrogen (the source of spin order) on an iridium catalyst Recently, we demonstrated that conducting SABRE in microtesla fields provided by a magnetic Shield enables up to 10% N-15-polarization (Theis, T.; et al. J. Am. Chem. Soc. 2015, 137, 1404). Hyperpolarization on N-15 (and heteronuclei in general) may be advantageous because of the long-lived nature of the hyperpolarization on N-15 relative to the short-lived hyperpolarization of protons conventionally hyperpolarized by, SABRE, in addition to wider chemical. Shift dispersion and absence of background signal. Here we show that these unprecedented polarization levels enable N-15 magnetic resonance imaging. We also present a theoretical model for the hyperpolarization transfer to heteronuclei, and detail key parameters that should be optimized far efficient N-15-hyperpolarization. The effects of parahydrogen pressure, flow rate, sample temperature, catalyst-to-substrate:ratio, relaxation time (T-1), and reversible oxygen quenching are studied on a test System of N-15-pyridine In methanol-d(4) Moreover, we demonstrate the first proof-of-principle C-13-hyperpolarization using this method. This simple hyperpolarization scheme only requires access to parahydrogen: and a magnetic Shield, and it provides large enough signal gain's to enable one of the first N-15 images (2 x mm(2) resolution). Importantly) this method enables hyperpolarization of molecular sites with NMR T-1 relaxation times suitable for biomedical imaging and spectroscopy.