Parahydrogen-Induced 13 C Hyperpolarizer Using a Flow Guide for Magnetic Field Cycling to Evoke 1 H- 13 C Spin Order Transfer Toward Metabolic MRI

• Published in: IEEE transactions on biomedical engineering 2024-07, Vol.71 (7), p.2224-2231
• Main Authors: Sawami, Koudai, Naganuma, Tatsuya, Yabe, Hana, Taki, Toshihiko, Stewart, Neil J, Uchio, Yoshiki, Takeda, Norihiko, Hatae, Noriyuki, Hashimoto, Takuya, Hirata, Hiroshi, Matsumoto, Shingo
• Format: Article
• Language: English
• Subjects: Animals; Carbon Isotopes - chemistry; Equipment Design; Hydrogen - chemistry; Magnetic Fields; Magnetic Resonance Imaging - methods; Mice; Phantoms, Imaging
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2024.3365195

The pair-wise addition of parahydrogen, the singlet form of molecular hydrogen, to unsaturated precursors evokes the hyperpolarization of two parahydrogen-derived H nuclear spins through a process known as parahydrogen-induced polarization (PHIP). Subsequent spin order transfer (SOT) from the H to the surrounding C nuclear spins via magnetic field cycling (MFC) results in substantial signal enhancement in C magnetic resonance imaging (MRI). Here, we report the development of a unique PHIP C hyperpolarizer system using a flow guide for MFC. The optimal MFC scheme for H to C spin order transfer was quantum-chemically simulated using the J-coupling values of C-labeled metabolic tracers. The flow guide system was three-dimensionally designed based on the simulated MFC scheme and pre-measured magnetic field distribution in a zero-field chamber. The system efficiently transfers the spin order of hyperpolarized H to a particular C spin when the parahydrogenated tracer passes through the flow guide at a designated flow rate. The C MRI signal is enhanced more than 40,000 times in C-labeled pyruvate and fumarate, compared to the thermal equilibrium level at 1.5 T, was achieved for conducting in vivo metabolic MRI of mice. A fully automated PHIP-based C polarizer was developed using a unique flow guide to conduct the MFC for H to C SOT. The PHIP hyperpolarizer with a flow guide can conduct efficient H- C SOT without a MFC magnetic field sweep system and offers a cost-effective alternative to conventional dynamic nuclear polarization.