Anterior to posterior hippocampal MRS metabolite difference is mainly a partial volume effect

作者:Starck Goran*; Vikhoff Baaz Barbro; Ljungberg Maria; Malmgren Kristina; Forssell Aronsson Eva; Jonsson Lars; Ekholm Sven
来源:Acta Radiologica, 2010, 51(3): 351-359.
DOI:10.3109/02841850903540401

摘要

Purpose: To re-evaluate MRS imaging data from prior control subjects with regard to variation of metabolite concentrations in hippocampus from anterior to posterior and the partial volume (R) contribution to the measurements from adjacent tissue.
Material and Methods: Twelve healthy subjects, mean age 33 years, were studied with MRS imaging. The measurement volume was angled along the temporal horns and metabolite concentration images were reconstructed at the MR system. Regions of interest (ROIs) in the anterior, medial, and posterior parts of both hippocampi were evaluated. Signal normalization to the total MRS signal from all ROIs permitted pooling of individual data with different and unknown signal scaling. One subject was re-examined with a high resolution three-dimensional (3D) volume of the brain for evaluation of partial volumes in the MRS examination.
Results: Overall, there were significantly lower concentrations of NAA in the anterior parts, and of (Cho+Cr) in the posterior parts, while the NAA/(Cho+Cr) ratio in the posterior parts of the mesial temporal lobes was significantly higher. Hippocampus accounted for one-half, one-third, and one-quarter of the anterior, middle, and posterior ROIs, respectively. The NAA/(Cho+Cr) ratio thus showed a reverse relationship to the relative volume of hippocampal tissue within the ROI.
Conclusion: Metabolite concentrations in the mesial temporal lobe obtained with MRS imaging represent the mean value of hippocampus and a considerable amount of adjacent tissue. To assess the hippocampus alone, an actual voxel well below 1 cm(3) and a sub-centimeter slice thickness are required.

  • 出版日期2010-4