Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized 13 C imaging

Abstract

Purpose: To develop symmetric echo planar imaging (EPI) and a reference scan framework for hyperpolarized ¹³ C metabolic imaging.

Methods: Symmetric, ramp-sampled EPI with partial Fourier reconstruction was implemented on a 3T scanner. The framework for acquiring a reference scan on the ¹ H channel and applied to ¹³ C data was described and validated in both phantoms and in vivo metabolism of [1-¹³ C]pyruvate.

Results: Ramp-sampled, symmetric EPI provided a substantial increase in the signal-to-noise ratio of the phantom experiments. The reference scan acquired on the ¹ H channel yielded ¹³ C phantom images that varied in mean signal intensity <2%, compared with ¹³ C images reconstructed with a reference scan directly measured on the ¹³ C channel. The structural similarity index and dynamic time course from in vivo ¹³ C data further support the application of a ¹ H reference scan to ¹³ C data to mitigate Nyquist ghost artifacts.

Conclusion: Ramp-sampled, symmetric EPI with spectral-spatial excitation of a single metabolite provides a fast, robust, and clinically efficacious approach to acquire hyperpolarized ¹³ C dynamic molecular imaging data. The gains of this efficient sampling, combined with partial Fourier methods, enables large matrix sizes required for human studies. Magn Reson Med 77:826-832, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: echoplanar imaging; hyperpolarized 13C; reference scan; spectroscopic imaging.