TABLE 2.
Comparison of spectral quality parameters for pons and thalamus at 3T vs. 7T.
| Pons |
Thalamus |
|||||
| 3T | 7T | p | 3T | 7T | p | |
| SNR (mean ± SE) | 17.70 ± 0.55 | 16.07 ± 1.26 | 0.006 | 15.71 ± 0.51 | 20.20 ± 0.99 | < 0.001 |
| FWHM (mean ± SE) | 0.05 ± 0.00 | 0.05 ± 0.00 | 0.079 | 0.04 ± 0.00 | 0.03 ± 0.00 | < 0.001 |
| Glx | ||||||
| CRLB (mean ± SE) | 11.59 ± 0.55 | 9.65 ± 0.61a | 0.002 | 9.07 ± 0.16 | 5.80 ± 0.30 | < 0.001 |
| Spectra—CRLB < 20 | 43/43 | 42/44a | – | 45/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 44/44a | – | 45/45 | 45/45 | – |
| Glutamate | ||||||
| CRLB (mean ± SE) | 16.3 ± 0.61 | 7.89 ± 0.87 | < 0.001 | 10.87 ± 0.22 | 4.78 ± 0.33 | < 0.001 |
| Spectra—CRLB < 20 | 34/43 | 45/45 | – | 45/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| Glutamine | ||||||
| CRLB (mean ± SE) | 30.92 ± 13.81 | 76.01 ± 10.27b | 0.003 | 26.87 ± 1.18 | 20.80 ± 1.61 | < 0.001 |
| Spectra—CRLB < 20 | 3/43 | 0/32b | – | 0/45 | 20/45 | – |
| Spectra—CRLB < 50 | 42/43 | 14/32b | – | 45/45 | 45/45 | – |
| GABA | ||||||
| CRLB (mean ± SE) | 88.50 ± 20.26 | 52.79 ± 17.60 | 0.090 | 44.89 ± 1.85 | 20.96 ± 1.94 | < 0.001 |
| Spectra—CRLB < 20 | 0/43 | 4/45 | – | 0/45 | 21/45 | – |
| Spectra—CRLB < 50 | 5/43 | 35/45 | – | 32/45 | 45/45 | – |
| tNAA | ||||||
| CRLB (mean ± SE) | 2.97 ± 0.09 | 1.84 ± 0.14 | 0.002 | 3.62 ± 0.10 | 1.89 ± 0.12 | < 0.001 |
| Spectra—CRLB < 20 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| tCreatine | ||||||
| CRLB (mean ± SE) | 3.82 ± 0.12 | 3.38 ± 0.20 | 0.002 | 3.05 ± 0.11 | 2.58 ± 0.11 | < 0.001 |
| Spectra—CRLB < 20 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| tCholine | ||||||
| CRLB (mean ± SE) | 3.14 ± 0.29 | 3.67 ± 0.22 | 0.076 | 5.07 ± 0.21 | 4.87 ± 0.20 | 0.339 |
| Spectra—CRLB < 20 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
| Myo-inositol | ||||||
| CRLB (mean ± SE) | 13.05 ± 0.71 | 5.24 ± 0.52 | < 0.001 | 16.87 ± 0.77 | 5.64 ± 0.62 | < 0.001 |
| Spectra—CRLB < 20 | 40/43 | 45/45 | – | 34/45 | 45/45 | – |
| Spectra—CRLB < 50 | 43/43 | 45/45 | – | 45/45 | 45/45 | – |
Mean CRLBs of metabolite estimates include all spectra for comparison between 3 and 7T. The numbers of spectra within the 20 as well as the 50 CRLB limits are reported for each metabolite as well. Absolute mean and standard error of the mean are reported from mixed model. aOne spectrum excluded due to an outlying value; two of the included spectra had a CRLB of 21. bTwelve spectra excluded due to undetectable values and one due to outlying value. SE, standard error of the mean; CRLB, Cramér–Rao lower bounds; SNR, signal noise ratio; FWHM, full-width of half-maximum, ppm; Glx, glutamate + glutamine; GABA, γ-aminobutyric acid; tNAA, N-acetylaspartate + N-acetylaspartyl glutamate; tCreatine, creatine + phophocreatine; tCholine, glycerophosphocholine + phosphocholine.