TOMOGRAPHY, June 2016, Volume 2, Issue 2: 117-124
Fast Padé Transform Accelerated CSI for Hyperpolarized MRS
1MR Research Centre, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark; 2Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford; 3Danish Diabetes Academy, Odense, Denmark; 4Department of Neurology & Neurological Sciences, Stanford Hospital & Clinics, Palo Alto, California; 5Department of Physics, University of Oxford, Oxford; 6School of Mathematical Sciences, University College Dublin, Belfield, Dublin, Ireland; 7University of Utah School of Medicine, Salt Lake City, Utah; and 8Utah Center for Advanced Imaging Research, Salt Lake City, Utah
The fast Padé transform (FPT) is a method of spectral analysis that can be used to reconstruct nuclear magnetic resonance spectra from truncated free induction decay signals with superior robustness and spectral resolution compared with conventional Fourier analysis. The aim of this study is to show the utility of FPT in reducing of the scan time required for hyperpolarized 13C chemical shift imaging (CSI) without sacrificing the ability to resolve a full spectrum. Simulations, phantom, and in vivo hyperpolarized [1-13C] pyruvate CSI data were processed with FPT and compared with conventional analysis methods. FPT shows improved stability and spectral resolution on truncated data compared with the fast Fourier transform and shows results that are comparable to those of the model-based fitting methods, enabling a reduction in the needed acquisition time in 13C CSI experiments. Using FPT can reduce the readout length in the spectral dimension by 2-6 times in 13C CSI compared with conventional Fourier analysis without sacrificing the spectral resolution. This increased speed is crucial for 13C CSI because T1 relaxation considerably limits the available scan time. In addition, FPT can also yield direct quantification of metabolite concentration without the additional peak analysis required in conventional Fourier analysis.