Two-site reproducibility of cerebellar and brainstem neurochemical profiles with short-echo, single-voxel MRS at 3T

Abstract

Purpose To determine if neurochemical concentrations obtained at two MRI sites using clinical 3 T scanners can be pooled when a highly optimized, non-vendor short-echo, single voxel proton MRS pulse sequence is utilized in conjunction with identical calibration and quantification procedures. Methods A modified semi-LASER sequence (TE = 28 ms) was used to acquire spectra from two brain regions (cerebellar vermis and pons) on two Siemens 3 T scanners using the same B0 and B1 calibration protocols from two different cohorts of healthy volunteers (N=24–33 per site) matched for age and BMI. Spectra were quantified with LCModel using water scaling. Results The spectral quality was very consistent between the two sites and allowed reliable quantification of at least 13 metabolites in the vermis and pons compared to 3 – 5 metabolites in prior multi-site MRS trials using vendor-provided sequences. The neurochemical profiles were nearly identical at the two sites and showed the feasibility to detect inter-individual differences in the healthy brain. Conclusion Highly reproducible neurochemical profiles can be obtained on different clinical 3 T scanners at different sites, provided that the same, optimized acquisition and analysis techniques are utilized. This will allow pooling of multi-site data in clinical studies, which is particularly critical for rare neurological diseases.

Multi‐center reproducibility of neurochemical profiles in the human brain at 7 T

“…The increased accuracy in detection of neurochemical profiles at UHF is supported by the lower CoV compared to other studies (8,10,25,26,28-33). This suggests that metabolites involved in inhibitory and excitatory neurotransmission, such as NAAG, Glu and Gln, can now be detected with higher accuracy.…”

“…Several other studies have investigated the variation in the level of metabolites in the human brain using MRS on lower field strengths (≤3T) (8,10,26,27) and on UHF at a single site (4-6,11). The increased accuracy in detection of neurochemical profiles at UHF is supported by the lower CoV compared to other studies (8,10,25,26,28-33).…”

Assessing recovery from neurodegeneration in spinocerebellar ataxia 1: Comparison of in vivo magnetic resonance spectroscopy with motor testing, gene expression and histology

“…Finally, an important limitation of MRS that needs to be addressed prior to utilizing the technique in multi-site clinical trials is the operator-dependence of voxel selection. While the voxel selection was very consistent in the abovementioned 2-site 3T study performed in the research setting (Deelchand et al, 2014a), it may be more variable in a multi-site clinical trial setting, where VOI are selected by rotating MR technologists. Therefore automated methods for VOI selection, as well as protocol execution, are critically needed in the field.…”

“…Another consideration for applicability of an imaging method for trials targeting a rare disease like SCA1 is that it can be utilized in a multi-site setting. We have recently demonstrated that identical neurochemical profiles are obtained from age- and gender-matched healthy populations by different operators at different 3T sites and that multi-site 3T MRS data collected from the cerebellum and the brainstem can be pooled (Deelchand et al, 2014a). Finally, an important limitation of MRS that needs to be addressed prior to utilizing the technique in multi-site clinical trials is the operator-dependence of voxel selection.…”

Quantitativein vivoneurochemical profiling in humans: where are we now?

“…It was already successfully demonstrated that simply upgrading the pulse sequence (software), which consisted of FASTMAP shimming 29,30 and semi-LASER localization 33 with VAPOR water suppression, 25,34 significantly improved the 1 H-MRS data quality and increased the range of reliably quantified metabolites from the original 3-5 (using vendor-provided sequences) up to 13. 21 In addition, the same methodology was implemented at two different institutions (the University of Minnesota, in Minneapolis, and the Institut du Cerveau et de la Moelle, in Paris) and the measured neurochemical profiles (vermis, ponds) were nearly identical between these sites. Moreover, this approach showed the feasibility to detect inter-individual differences in the healthy brain.…”