Flow-suppressed hyperpolarized 13C chemical shift imaging using velocity-optimized bipolar gradient in mouse liver tumors at 9.4 T

Abstract

Purpose : To optimize and investigate the influence of bipolar gradients for flow suppression in metabolic quantification of hyperpolarized 13C chemical shift imaging (CSI) of mouse liver at 9.4?T.

Methods : The trade-off between the amount of flow suppression using bipolar gradients and math formula effect from static spins was simulated. A free induction decay CSI sequence with alternations between the flow-suppressed and non?flow-suppressed acquisitions for each repetition time was developed and was applied to liver tumor?bearing mice via injection of hyperpolarized [1-13C] pyruvate.

Results : The in vivo results from flow suppression using the velocity-optimized bipolar gradient were comparable with the simulation results. The vascular signal was adequately suppressed and signal loss in stationary tissue was minimized. Application of the velocity-optimized bipolar gradient to tumor-bearing mice showed reduction in the vessel-derived pyruvate signal contamination, and the average lactate/pyruvate ratio increased by 0.095 (P?<?0.05) in the tumor region after flow suppression.

Conclusion : Optimization of the bipolar gradient is essential because of the short 13C math formula and high signal in venous flow in the mouse liver. The proposed velocity-optimized bipolar gradient can suppress the vascular signal, minimizing math formula-related signal loss in stationary tissues at 9.4?T. Magn Reson Med, 2016. ? 2016 International Society for Magnetic Resonance in Medicine.