TABLE II.
Measurement results in two MRI scanners. Values are average of five repetitions.
| 1.5 T scanner | 3.0 T scanner | |
|---|---|---|
| SNR | ||
| Phantom center | 20.7 | 60.2 |
| Uncertainty | 2.1 | 2.5 |
| Phantom periphery | ||
| Median (minimum, maximum) | 37.9 (34.0, 42.0) | 106.7 (87.2, 125.7) |
| Uncertainty | 3.0 | 13.3 |
| EPI readout distortion along phase-encoding direction (mm) | ||
| Median (minimum, maximum) | −4.6 (−6.9, −0.4) | −7.1 (−10.0, −0.5) |
| Uncertainty | 0.4 | 0.6 |
| Image distortion from diffusion-encoding gradient in phase-encoding direction (mm) | ||
| Median (minimum, maximum) | ||
| yb, before registration | 0.06 (0.01, 0.16) | 0.09 (−0.20, 0.41) |
| σ, before registration | 0.49 (0.27, 0.77) | 0.40 (0.08, 0.69) |
| yb, after registration | 0.04 (−0.04, 0.11) | 0.00 (−0.20, 0.11) |
| σ, after registration | 0.58 (0.41, 0.81) | 0.33 (0.08, 0.53) |
| uncertainty of yb | 0.08 | 0.06 |
| uncertainty of σ | 0.13 | 0.13 |
| FA | ||
| Pixel-based, mean ± SD | 0.098 ± 0.037 | 0.044 ± 0.017 |
| Uncertainties in mean ± SD | 0.001 ± 0.001 | 0.001 ± 0.001 |
| ROI-based | 0.0083 | 0.0098 |
| Uncertainty | 0.0008 | 0.0007 |
| MD (10−3 mm2/s) | ||
| Pixel-based, mean ± SD | 2.025 ± 0.065a | 2.038 ± 0.039b |
| Uncertainties in mean ± SD | 0.001 ± 0.002 | 0.001 ± 0.002 |
| ROI-based | 1.998 | 2.033 |
| Uncertainty | 0.001 | 0.002 |
a
Temperature = 19.3 °C, reference MD value 1.988 × 10−3 mm2/s.
b
Temperature = 19.4 °C, reference MD value 1.993 × 10−3 mm2/s.