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Magn Reson Med. 2011 Mar;65(3):610-9. doi: 10.1002/mrm.22650. Epub 2010 Oct 11.

Fast dynamic 3D MR spectroscopic imaging with compressed sensing and multiband excitation pulses for hyperpolarized 13C studies.

Author information

1
Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, California 94158, USA. peder.larson@ucsf.edu

Abstract

Hyperpolarized 13C MR spectroscopic imaging can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient hyperpolarization usage and rapid acquisitions. In this work, we have developed a time-resolved 3D MR spectroscopic imaging method for acquiring hyperpolarized 13C data by combining compressed sensing methods for acceleration and multiband excitation pulses to efficiently use the magnetization. This method achieved a 2 sec temporal resolution with full volumetric coverage of a mouse, and metabolites were observed for up to 60 sec following injection of hyperpolarized [1-(13)C]-pyruvate. The compressed sensing acquisition used random phase encode gradient blips to create a novel random undersampling pattern tailored to dynamic MR spectroscopic imaging with sampling incoherency in four (time, frequency, and two spatial) dimensions. The reconstruction was also tailored to dynamic MR spectroscopic imaging by applying a temporal wavelet sparsifying transform to exploit the inherent temporal sparsity. Customized multiband excitation pulses were designed with a lower flip angle for the [1-(13)C]-pyruvate substrate given its higher concentration than its metabolic products ([1-(13)C]-lactate and [1-(13)C]-alanine), thus using less hyperpolarization per excitation. This approach has enabled the monitoring of perfusion and uptake of the pyruvate, and the conversion dynamics to lactate and alanine throughout a volume with high spatial and temporal resolution.

PMID:
20939089
PMCID:
PMC3021589
DOI:
10.1002/mrm.22650
[Indexed for MEDLINE]
Free PMC Article

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