UNIVERSITY OF TEXAS AT DALLAS Richardson United States
This study involved the use of hyperpolarized 15N choline as potential magnetic resonance imaging MRI metabolic agent for prostate cancer diagnostics. The main goal of this study was to monitor the anticipated high uptake of choline in tumors and the subsequent overproduction of phosphocholine due to overexpression of choline kinase. Using dissolution dynamic nuclear polarization DNP method, the MRI signal of 15N-enriched choline was amplified to about 48,000-fold measured in a 9.4 T magnet at 298 K. The 15N spin-lattice relaxation time of hyperpolarized choline in the liquid-state was found to be 240 s or 4 minutes. Hyperpolarized 15N choline was tested in vitro in PC-3 prostate cancer cells. We have found that choline metabolism is relatively slow in which it could take several hours to have substantial production of phosphocholinea time scale which is outside the 8-10 minute observation window of hyperpolarized 15N MRI. The scientific efforts in this project have resulted in a number of research papers regarding optimization of hyperpolarized MRI signals and improvement of protocols for metabolic cell studies using hyperpolarization.