Optimized [1-(13)C]glucose infusion protocol for 13C magnetic resonance spectroscopy at 3T of human brain glucose metabolism under euglycemic and hypoglycemic conditions

Abstract

The effect of insulin-induced hypoglycemia on cerebral glucose metabolism is largely unknown. (13)C MRS is a unique tool to study cerebral glucose metabolism, but the concurrent requirement for [1-(13)C]glucose administration limits its use under hypoglycemic conditions. To facilitate (13)C MRS data analysis we designed separate [1-(13)C]glucose infusion protocols for hyperinsulinemic euglycemic and hypoglycemic clamps in such a way that plasma isotopic enrichment of glucose was stable and comparable under both glycemic conditions. (13)C MR spectra were acquired with optimized (13)C MRS measurement techniques to obtain high quality (13)C MR spectra with these protocols.

Conflict of interest statement

Disclosure/conflict of interest

The authors have no conflicts of interest to disclose relevant to this paper.

(c) 2009 Elsevier B.V. All rights reserved.

Figures

Figure 1

Plasma glucose levels of protocol 1 (panel a) and protocol 2 (panel b), and corresponding fractional 13C isotopic enrichment of plasma glucose (panels c and d). Data from 1 subject receiving 100% enriched [1-13C]glucose during hypoglycemia (gray) is separated from the results of the other 3 subjects who received 30% enriched [1-13C]glucose (black) (panel c). All data are expressed as mean ± sd.

Figure 2

a) Representative MR spectra of one subject under hypoglycemic condition (protocol 2), averaged over 20 minutes. b) Curves of Glutamate-C4 signal integral in protocol 2 as a function of time under hypoglycemia (light gray), under euglycemia (dark gray) and for protocol 1, where a euglycemic period with 30% enriched [1-13C]glucose infusion was followed by a hypoglycemic period with infusion of 100% enriched [1-13C]glucose (black).