Table II.
Volume data (Mean, SD) for contrast‐to‐noise ratios (CNR), intracranial volume (ICV), and whole brain GM, WM, and CSF measured at each site for the sample of five subjects and using two tissue segmentation methods (see Methods)
| GE_1 | GE_2 | PHILIPS | SIEMENS_1 | SIEMENS_2 | Intersite CV | % Diff max–min | Effect size max–min | ICC | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | |||||
| ICV (cc) | 1,422 | 113 | 1,448 | 118 | 1,443 | 97.7 | 1,469 | 90.6 | 1,479 | 102 | 1.9 | 3.9 | 0.3 (0.2)a | 0.991 |
| T1 and T2 Segm. | ||||||||||||||
| CNRi | 2.01 | 0.09 | 1.91 | 0.08 | 1.80 | 0.08 | 1.66 | 0.07 | 0.68 | 0.09 | ||||
| GM (cc) | 719.2 | 80.4 | 728.5 | 63.7 | 727.5 | 56.7 | 737.4 | 46.3 | 762.4 | 70.6 | 3.0 | 5.8 | 0.4 (0.1) | 0.979 |
| WM (cc) | 413.0 | 36.7 | 413.9 | 48.5 | 434.6 | 41.0 | 453.5 | 52.8 | 425.8 | 35.1 | 4.7 | 9.3 | 0.7 (0.1) | 0.980 |
| CSF (cc) | 290.1 | 24.6 | 305.8 | 41.8 | 281.6 | 20.7 | 278.1 | 20.5 | 291.3 | 23.0 | 5.6 | 9.5 | 0.7 (0.4) | 0.900 |
| GM (%) | 50.5 | 2.2 | 50.3 | 1.8 | 50.4 | 1.0 | 50.2 | 0.6 | 51.5 | 1.5 | 1.8 | 2.6 | 1.0 (0.1) | 0.899 |
| WM (%) | 29.1 | 1.9 | 28.5 | 1.6 | 30.1 | 1.1 | 30.8 | 1.8 | 28.8 | 0.6 | 4.6 | 7.8 | 1.2 (0.3) | 0.777 |
| CSF (%) | 20.5 | 1.8 | 21.2 | 2.6 | 19.6 | 1.7 | 19.0 | 2.1 | 19.8 | 2.1 | 5.2 | 10.9 | 0.8 (0.3) | 0.956 |
| T1 Segm. | ||||||||||||||
| CNRi | 2.17 | 0.12 | 2.08 | 0.08 | 2.03 | 0.04 | 2.04 | 0.09 | 1.08 | 0.16 | ||||
| GM (cc) | 784.9 | 79.5 | 807.4 | 67.4 | 777.7 | 64.0 | 779.5 | 59.0 | 747.3 | 55.2 | 3.3 | 7.7 | 0.8 (0.3) | 0.984 |
| WM (cc) | 400.0 | 36.7 | 399.5 | 44.0 | 431.0 | 41.1 | 439.1 | 53.4 | 481.8 | 50.2 | 8.2 | 18.7 | 1.5 (0.1) | 0.981 |
| CSF (cc) | 233.6 | 16.6 | 240.3 | 29.8 | 232.4 | 24.1 | 250.0 | 22.9 | 250.3 | 23.1 | 6.4 | 7.4 | 0.6 (0.3) | 0.836 |
| GM (%) | 55.3 | 1.7 | 55.8 | 1.1 | 54.3 | 1.1 | 52.9 | 1.0 | 50.5 | 0.7 | 4.1 | 10.0 | 5.1 (0.3) | 0.821 |
| WM (%) | 28.2 | 1.7 | 27.6 | 1.2 | 29.5 | 1.1 | 30.0 | 1.8 | 32.5 | 1.6 | 7.2 | 16.3 | 3.1 (0.4) | 0.803 |
| CSF (%) | 16.5 | 1.4 | 16.6 | 2.0 | 16.2 | 2.1 | 17.1 | 2.5 | 17.0 | 1.9 | 5.2 | 5.4 | 0.3 (0.1) | 0.940 |
Intersite CV: average of within subject coefficients of variation between scanners: % Diff max–min: percentage difference between maximum and minimum values among scanners; Effect size max–min: Cohen's effect size coefficient measuring the magnitude of the differences between the maximum and minimum values among scanners; ICC: intraclass correlation coefficient.
a
Values in parentheses are Cohen's effect size coefficient of the differences between GE_1 and GE_2 only.