Department of Anesthesiology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
Magn Reson Imaging. 2013 Sep;31(7):1197-205. doi: 10.1016/j.mri.2013.04.001. Epub 2013 May 6.
Partial volume effects in proton magnetic resonance spectroscopy in the brain have been studied previously in terms of proper water concentration calculations, but there is a lack of disclosure in terms of voxel placement techniques that would affect the calculations. The purpose of this study is to facilitate a fully automated MRS voxel registration method which is time efficient, accurate, and can be extended to all imaging modalities. A total of thirteen healthy adults underwent single voxel 1H-MRS scans in 3.0T MRI scanners. Transposition of a MRS voxel onto an anatomical scan is derived along with a full calculation of water concentration with a correction term to account for the partial volume effects. Five metabolites (tNAA, Glx, tCr, mI, and tCho) known to yield high reliability are studied. Pearson's correlation analyses between tissue volume fractions and metabolite concentrations were statistically significant in parietal (tCr, Glx, and tNAA) lobe and occipital lobe (tNAA). MRS voxel overlaps quantified by dice metric over repeated visits yielded 60%70% and coefficients of variance in metabolites concentration were 4%10%. These findings reiterate an importance of considering the partial volume effects when tissue water is used as an internal concentration reference so as to avoid misinterpreting a morphometric difference as a metabolic difference.
此前，已有研究从适当的水浓度计算方面研究了质子磁共振波谱（MRS）在大脑中的部分容积效应，但在可能影响计算的体素放置技术方面缺乏披露。本研究旨在促进一种全自动 MRS 体素配准方法，该方法具有高效、准确的特点，并且可以扩展到所有成像方式。共有 13 名健康成年人在 3.0T MRI 扫描仪上进行了单体素 1H-MRS 扫描。沿着解剖扫描置换 MRS 体素，并通过部分容积效应的校正项来计算水浓度的完整计算。研究了已知具有高可靠性的五种代谢物（tNAA、Glx、tCr、mI 和 tCho）。组织体积分数与代谢物浓度之间的 Pearson 相关分析在顶叶（tCr、Glx 和 tNAA）和枕叶（tNAA）中具有统计学意义。通过重复访问计算的 Dice 度量的 MRS 体素重叠率为 60%70%，代谢物浓度的变异系数为 4%10%。这些发现强调了在将组织水用作内部浓度参考时考虑部分容积效应的重要性，以避免将形态差异误解为代谢差异。
