Parahydrogen-induced polarization in imaging: Subsecond C-13 angiography

High nuclear spin polarization of C-13 was reached in organic molecules. En hancements of up to 10(4), compared to thermal polarization at 1.5 T, were achieved using the parahydrogen-induced polarization technique in combinati on with a field cycling method. While parahydrogen has no net polarization, it has a high spin order, which is retained when hydrogen is incorporated into another molecule by a chemical reaction. By subjecting this molecule t o a sudden change of the external magnetic field, the spin order is transfe rred into net polarization. A C-13 angiogram of an animal was generated in less than a second. (C) 2001 Wiley-Liss, Inc.