Rapid in vivo apparent diffusion coefficient mapping of hyperpolarized 13C metabolites. Issue 3 (11th September 2014) - Koelsch, Bertram L.
Abstract Purpose Hyperpolarized 13C magnetic resonance allows for the study of real‐time metabolism in vivo, including significant hyperpolarized 13C lactate production in many tumors. Other studies have shown that aggressive and highly metastatic tumors rapidly transport lactate out of cells. Thus, the ability to not only measure the production of hyperpolarized 13C lactate but also understand its compartmentalization using diffusion‐weighted MR will provide unique information for improved tumor characterization. Methods We used a bipolar, pulsed‐gradient, double spin echo imaging sequence to rapidly generate diffusion‐weighted images of hyperpolarized 13C metabolites. Our methodology included a simultaneously acquired B1 map to improve apparent diffusion coefficient (ADC) accuracy and a diffusion‐compensated variable flip angle scheme to improve ADC precision. Results We validated this sequence and methodology in hyperpolarized 13C phantoms. Next, we generated ADC maps of several hyperpolarized 13C metabolites in a normal rat, rat brain tumor, and prostate cancer mouse model using both preclinical and clinical trial‐ready hardware. Conclusion ADC maps of hyperpolarized 13C metabolites provide information about the localization of these molecules in the tissue microenvironment. The methodology presented here allows for further studies to investigate ADC changes due to disease state that may provide unique information about cancer aggressiveness and metastatic potential. Magn Reson Med 74:622–633, 2015. © 2014 Wiley Periodicals, Inc.