Improved reconstruction stability for chemical shift encoded hyperpolarized 13 C magnetic resonance spectroscopic imaging using k‐t spiral acquisitions
[1];
[1];
[5]
- Department of Medical Physics University of Wisconsin‐Madison Madison Wisconsin
- Department of Medical Physics University of Wisconsin‐Madison Madison Wisconsin, Morgridge Institute for Research University of Wisconsin‐Madison Madison Wisconsin, Laboratory for Optical and Computational Instrumentation University of Wisconsin‐Madison Madison Wisconsin
- Department of Medical Physics University of Wisconsin‐Madison Madison Wisconsin, Department of Radiology University of Wisconsin‐Madison Madison Wisconsin
- Department of Medical Physics University of Wisconsin‐Madison Madison Wisconsin, Department of Radiology University of Wisconsin‐Madison Madison Wisconsin, Carbone Cancer Center University of Wisconsin‐Madison Madison Wisconsin
- Department of Medical Physics University of Wisconsin‐Madison Madison Wisconsin, Department of Radiology University of Wisconsin‐Madison Madison Wisconsin, Department of Biomedical Engineering University of Wisconsin‐Madison Madison Wisconsin
Purpose A multiecho, field of view (FOV)‐oversampled k‐t spiral acquisition and direct iterative decomposition of water and fat with echo asymmetry and least‐squares estimation reconstruction is demonstrated to improve the stability of hyperpolarized 13 C magnetic resonance spectroscopic imaging (MRSI) in the presence of signal ambiguities attributed to low‐SNR (signal‐to‐noise‐ratio) species, local uncertainties in metabolite peaks, and echo‐to‐echo signal inconsistencies. Theory k‐t spiral acquisitions redistribute readout points to be more densely spaced radially in k‐space by acquiring an FOV and matrix that are oversampled by η . These more densely spaced spiral turns constitute effective intraspiral echoes and can supplement conventional interspiral echoes to improve spectral separation and reduce spectral cross‐talk to better resolve 13 C‐labeled species for spectroscopic imaging. Methods Digital simulations and imaging phantom experiments were performed for a range of interspiral echo spacings and η using multiecho, k‐t spiral acquisitions. Image spectral cross‐talk artifacts were evaluated both qualitatively and quantitatively as the percent error in measured metabolite ratios. In vivo murine experiments evaluated the feasibility of multiecho, k‐t spiral [1‐ 13 C]pyruvate MRSI to reduce spectral cross‐talk for 3 scenarios of different expected reconstruction stability. Results Digital simulations and imaging phantom experiments both demonstrated reduced or comparable image spectral cross‐talk and percent errors in measured metabolite ratios with increasing η and better choices of echo spacings. In vivo images displayed markedly reduced spectral cross‐talk in lactate images acquired with η = 7 versus η = 1. Conclusion The precision of hyperpolarized 13 C metabolic imaging and quantification in the presence of low‐SNR species, local uncertainties in metabolite resonances, and echo‐to‐echo signal inconsistencies can be improved with the use of FOV‐oversampled k‐t spiral acquisitions.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1577881
- Journal Information:
- Magnetic Resonance in Medicine, Journal Name: Magnetic Resonance in Medicine Vol. 84 Journal Issue: 1; ISSN 0740-3194
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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