Ultra-fast three dimensional imaging of hyperpolarized ¹³C in vivo

Objective: PASADENA, a chemical method of enhancing nuclear spin polarization has demonstrated ¹³C polarizations of order unity for the nascent products of molecular addition by parahydrogen. The extreme brevity of signal enhancement obtained by hyperpolarization requires improved ¹³C MR in vivo imaging techniques for their optimum utility. Materials and Methods: ¹³C imaging sequences, including ¹³C 3D FIESTA, were compiled for a GE LX 1.5 T clinical MR scanner. Two water soluble ¹³C imaging agents were hyperpolarized utilizing parahydrogen and an automated polarizer. ¹³C polarization was quantified in flow phantoms and in rats with jugular vein catheters. Results: Fast 3D FIESTA ¹³C MR imaging technique acquired sequential 3D images (3.66 s/acquisition) with superior SNR. Hyperpolarized ¹³C solutions and vascular phantoms achieved a maximum signal of 26,624±593. In vivo ¹³C MR images of the cardiopulmonary circulation showed maximum ¹³C signal of 2,402±158. ¹³C images acquired within 3.66 s showed signal enhancement over 10,000 compared to equilibrium polarization. Conclusion: 3D-FIESTA was effective for sub-second in vivo imaging of hyperpolarized ¹³C reagents produced in a custom-built parahydrogen polarizer. Application to ¹³C hyperpolarized by parahydrogen is demonstrated in vitro and in vivo.