Purpose
A feasibility study of a short TE EPSI that trades off sensitivity, compared with other short-TE methods, to achieve whole brain coverage, using inversion recovery and spatial oversampling to control lipid bleeding.
Methods
Twenty subjects were scanned to examine inter-subject variance. One subject was scanned 5 times to examine intra-subject reproducibility. Data were analyzed to determine coefficients of variance (COV) and intra-class correlation coefficient (ICC) for N–acetylaspartate (NAA), total creatine (tCr), choline (Cho), glutamine/glutamate (Glx) and myo-inositol (ml). Regional metabolite concentrations were derived by using multi-voxel analysis based on lobar level anatomic regions.
Results
For whole brain mean values the intra-subject COVs were 14%, 15%, and 20% for NAA, tCr, and Cho respectively, and 31% for Glx and ml. The inter-subject COVs were up to 6% higher. For regional distributions the intra-subject COVs were ≤ 5% for NAA, tCr, Cho, ≤ 9% for Glx, and ≤15% for ml, with about 6% higher inter-subject COVs. The ICCs of 5 metabolites were ≥ 0.7, indicating the reliability of the measurements.
Conclusion
The present EPSI method enables estimation of the whole brain metabolite distributions including Glx and ml with small voxel size, and a reasonable scan time and reproducibility.
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