Purpose: To measure the apparent diffusion coefficients (ADC) of five main metabolites in the human brain at 3T with PRESS and STEAM, avoiding measurement biases because of cross-terms. Cross-terms arise from interactions between slice-selection and spoiler gradients in the localized spectroscopy sequence and the diffusion gradients. Methods: Diffusion-weighted spectra were acquired from the prefrontal cortex in five healthy subjects using STEAM (echo time [TE]/mixing time [TM]/pulse repetition time [TR] = 21.22/105/3000 ms, b-values = 0 and 3172 s/mm2) and PRESS (TE/TR = 54.2/3000 ms, b-values = 0 and 2204 s/mm2). Diffusion weighting was applied using bipolar gradients in three orthogonal directions. Post-processed spectra were analyzed with LCModel, and the trace/3 ADC values were calculated. Results: Comparable trace/3 ADC values (0.14–0.18 µm2/ms) were obtained for five main metabolites with both methods. These metabolites were quantified with Cramér-Rao lower bounds below 15%. Conclusion: The ADC values of the five main metabolites were successfully measured in the human brain at 3T with eliminated directional dependence. Both STEAM and PRESS can be used to probe the diffusivity of metabolites in normal brain and various pathologies on the clinical scanner with slightly higher precision achieved with STEAM for glutamate and myo-inositol. Magn Reson Med 79:2896–2901, 2018.
Bibliographical noteFunding Information:
Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA. Grant sponsor: National Institutes of Health (NIH); Grant numbers: R21AG045606, P41 EB015894, P30 NS076408. *Correspondence to: Dinesh K. Deelchand, PhD, Center for Magnetic Resonance Research, University of Minnesota, 2021 6th Street SE, Minneapolis, MN 55455, USA. E-mail: firstname.lastname@example.org Received 20 June 2017; revised 29 August 2017; accepted 21 September 2017 DOI 10.1002/mrm.26969 Published online 17 October 2017 in Wiley Online Library (wileyonlinelibrary. com).