Three‐dimensional accelerated acquisition for hyperpolarized ¹³C MR  with blipped stack‐of‐spirals and conjugate‐gradient  SENSE

Abstract

Purpose: To test a new parallel imaging strategy for acceleration of hyperpolarized 13 C MR acquisitions based on a 3D blipped-stack-of-spirals trajectory and conjugate gradient SENSE reconstruction with pre-calibrated sensitivities. Methods:The blipped-stack-of-spirals trajectory was developed for an acceleration factor of four, based on an undersampled stack-of-spirals with gradient blips during spiral readout. The trajectory was developed with volumetric coverage of a large FOV and with high spatial resolution. High temporal resolution was attained through spectral-spatial excitation and four excitations per volume. The blipped-stack-of-spirals was evaluated in simulations and phantom experiments. Next, the method was evaluated for kidney and cardiac imaging in two separate healthy pigs.Results: Simulation and phantom results showed successful acquisition and reconstruction, but also revealed reconstruction challenges for certain locations and for wide signal sources. For the kidney experiment, the accelerated acquisition showed high similarity to two separately acquired fully sampled datasets with matched spatial and temporal resolution, respectively. For the cardiac experiment, the accelerated acquisition proved able to map each metabolite in three dimensions within a single cardiac cycle. Conclusion:The proposed method demonstrated effective mapping of metabolism in both kidneys and heart of healthy pigs. Limitations seen in phantom experiments, may be irrelevant for most clinical applications, but should be kept in mind as well as reconstruction challenges related to residual aliasing. All in all, we show that the blipped-stack-of-spirals is a relevant parallel imaging method for hyperpolarized human imaging, facilitating better insights into metabolism compared to nonaccelerated acquisition.