Exchange-linked dissolution agents in dissolution-DNP 13C metabolic imaging

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Abstract

Purpose

The use of unlabeled exchange-linked dissolution agents in hyperpolarized metabolic imaging was studied to examine pool size limits and saturation relative to the availability of NADH.

Methods

Three-dimensional dynamic metabolic images were obtained, and compared following injection of a bolus of hyperpolarized [1-13C]pyruvate, prepared with and without unlabeled sodium lactate in the dissolution buffer. Comparisons were made on the basis of apparent rate constants and [1-13C]lactate signal-to-noise ratio. Range finding data were obtained for different bolus compositions. Isotope exchange was also probed in the reverse direction, following injection of a bolus of hyperpolarized [1-13C]lactate, with and without unlabeled sodium pyruvate in the dissolution buffer.

Results

Liver, kidney, and vascular regions of interest all showed an increase in [1-13C]lactate signal with addition of unlabeled sodium lactate in the dissolution buffer. Injection of hyperpolarized [1-13C]lactate with unlabeled sodium pyruvate in the dissolution buffer, provided exchange rate constants Klp for kidney and vascular regions of interest.

Conclusions

These results are consistent with a high level of 13C-exchange, and with labeling rates that are limited by steady-state pool sizes in vivo. Magn Reson Med, 70:936–942, 2013. © 2012 Wiley Periodicals, Inc.

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