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The role of gray and white matter segmentation in quantitative proton MR spectroscopic imaging
| Content Provider | Scilit |
|---|---|
| Author | Tal, Assaf Kirov, Ivan I. Grossman, Robert I. Gonen, Oded |
| Copyright Year | 2012 |
| Description | Journal: NMR in Biomedicine Since the brain's gray matter (GM) and white matter (WM) metabolite concentrations differ, their partial volumes can vary the voxel's$ ^{1}$H MR spectroscopy $(^{1}$H‐MRS) signal, reducing sensitivity to changes. While single‐voxel$ ^{1}$H‐MRS cannot differentiate between WM and GM signals, partial volume correction is feasible by MR spectroscopic imaging (MRSI) using segmentation of the MRI acquired for VOI placement. To determine the magnitude of this effect on metabolic quantification, we segmented a $1‐mm^{3}$ resolution MRI into GM, WM and CSF masks that were co‐registered with the MRSI grid to yield their partial volumes in approximately every 1 $cm^{3}$ spectroscopic voxel. Each voxel then provided one equation with two unknowns: its i‐ metabolite's GM and WM concentrations C_{i}$^{GM}$, C_{i}$^{WM}$. With the voxels' GM and WM volumes as independent coefficients, the over‐determined system of equations was solved for the global averaged C_{i}$^{GM}$ and C_{i}$^{WM}$. Trading off local concentration differences offers three advantages: (i) higher sensitivity due to combined data from many voxels; (ii) improved specificity to WM versus GM changes; and (iii) reduced susceptibility to partial volume effects. These improvements made no additional demands on the protocol, measurement time or hardware. Applying this approach to 18 volunteered 3D MRSI sets of 480 voxels each yielded N‐acetylaspartate, creatine, choline and myo‐inositol C_{i}$^{GM}$ concentrations of 8.5 ± 0.7, 6.9 ± 0.6, 1.2 ± 0.2, 5.3 ± 0.6mM, respectively, and C_{i}$^{WM}$ concentrations of 7.7 ± 0.6, 4.9 ± 0.5, 1.4 ± 0.1 and 4.4 ± 0.6mM, respectively. We showed that unaccounted voxel WM or GM partial volume can vary absolute quantification by 5–10% (more for ratios), which can often double the sample size required to establish statistical significance. Copyright © 2012 John Wiley & Sons, Ltd. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3449040/pdf |
| Ending Page | 1400 |
| Page Count | 9 |
| Starting Page | 1392 |
| e-ISSN | 10991492 |
| DOI | 10.1002/nbm.2812 |
| Journal | NMR in Biomedicine |
| Issue Number | 12 |
| Volume Number | 25 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 2012-06-20 |
| Access Restriction | Open |
| Subject Keyword | Journal: NMR in Biomedicine Radiology, Nuclear Medicine and Imaging Spectroscopic Quantification Mrs |
| Content Type | Text |
| Resource Type | Article |
