Table 1.
Summary of MRI acquisition parameters. The in-plane field of view is 256 × 256. TR: repetition time; TE: echo time; MTR: magnetization transfer ratio; off res frequency: frequency offset for the off resonance pulse.
| Sequence | TR/TE (ms) | 2D or 3D | MTR |
TI (ms) | Voxel dimensions (mm × mm × mm) | Number of gradient directions | Number of averages | Acquisition time (min) | |
|---|---|---|---|---|---|---|---|---|---|
| Off res frequency | Ampl | ||||||||
| MPRAGE | 8.1/3.7 | 3D | N/A | N/A | 1071 | 1 × 1 × 1 | N/A | 1 | 5:56.1 |
| FLAIR | 8000/337 | 3D | 2400 | 1 × 1 × 1 | N/A | 1 | 8:24.0 | ||
| Gradient echo (for MTR) | 65/5.9 | 3D | 2100 Hz | 2.34 uT or 6200 | 1.25 × 1.25 × 3 | N/A | 1 | 5:01.9 | |
| Dual gradient echo (T2-weighted) | 510/16/32 | 2D | N/A | N/A | N/A | 1 × 1 × 3 | N/A | 1 | 4:33.4 |
| PRESS (for MRSI) | 2000/53a | 2D | N/A | N/A | N/A | 10 × 10 × 15 | N/A | 1 | 8:26.0 |
| EPI (DWI) | 8000/55 | 2D | N/A | N/A | N/A | 2 × 2 × 3 | 32 | 1 | 5:46.9 |
a
Minimum echo time allowed on the scanner for the MRSI protocol used in this study.