Toward Next-Generation Molecular Imaging with a Clinical Low-Field (0.064 T) Point-of-Care MRI Scanner

Low-field (LF) MRI promises soft-tissue imaging without the expensive, immobile magnets of clinical scanners but generally suffers from limited detection sensitivity and contrast. The sensitivity boost provided by hyperpolarization can thus be highly synergistic with LF MRI. Initial efforts to integrate a continuous-bubbling SABRE (signal amplification by reversible exchange) hyperpolarization setup with a portable, point-of-care 64 mT clinical MRI scanner are reported. Results from ¹H SABRE MRI of pyrazine and nicotinamide are compared with those of benchtop NMR spectroscopy. Comparison with MRI signals from samples with known H₂O/D₂O ratios allowed quantification of the SABRE enhancements of imaged samples with various substrate concentrations (down to 3 mM). Respective limits of detection and quantification of 3.3 and 10.1 mM were determined with pyrazine ¹H polarization (P_H) enhancements of ∼1900 (P_H ∼0.04%), supporting ongoing and envisioned efforts to realize SABRE-enabled MRI-based molecular imaging.