Table 3. Variable flip angle (VFA) measurement protocols.
| T1—VFA Series | GE Medical Systems | Philips | Siemens |
|---|---|---|---|
| Sequence | 3D/FSPGR | 3D/SPGR | 3D/RF spoiled GRE |
| Scan Plane | COR | COR | COR |
| Scan Options | EDR/Z2 | 3D FFE; Fast = none | |
| Section Thickness/Gap (mm) | 3/0 | 6/0 | 6/0 (or 3/0 if error) |
| TR (ms) | Min (6.0) | 6.6 | 6.6 |
| TE (ms) | Min (1.4) | 1.8 | 2.44 |
| TI Values (ms) | |||
| Flip Angle (deg) | 2, 5, 10, 20, 25, 30 | 2, 5, 10, 20, 25, 30 | 2, 5, 10, 20, 25, 30 |
| ETL (Echo Train Length) | 1 | 1 | 1 |
| Number of Averages | 4 | 4 | 4 |
| Matrix (Frequency Encode) | 256 | 256 | 256 |
| Matrix (Phase Encode) | 192 | 192 | 192 |
| Matrix (Slice Encode)/# of Slices | 34 | 28 | 32 |
| Pixel Bandwidth (Hz) | 488 | 904 | 280 |
| Bandwidth (kHz)–GE only | 62.5 | ||
| FOV (FE, mm) | 250 | 250 | 250 |
| FOV (PE, mm) | 250 | 250 | 250 |
| Pixel Size (mm x mm) | 0.98 x 0.98 | 0.98 x 0.98 | 0.98 x 0.98 |
| Phase Encode Direction | RL | RL | RL |
| User CVs | Turbo = 0 | ||
| Notes | 1) Yields 30 3-mm sections. 2) Autoprescan with FA = 15. 3) Ensure gain settings do not vary between series, i.e., use Manual Prescan. 4) Include fiducial spheres above & below T1 spheres in scan volume. 5) Using Turbo = 0 should maintain the same TE/TR for each FA. |
1) Reconstructed at 3 mm. 2) Ensure gain settings do not vary between series, i.e., use MPS. Autoprescan using 15 deg FA. 3) Include fiducial spheres above & below T1 spheres in scan volume. |
1) Reconstructed at 3 mm. 2) Ensure gain settings do not vary between series, i.e., use MPS. Autoprescan using 15 deg FA. 3) Include fiducial spheres above & below T1 spheres in scan volume. |
| Series | T1 VFA | T1 VFA | T1 VFA |
| Approximate Acquisition Time per Flip Angle Setting (min) | 2.6 | 3.0 | 1.23 |
| # of Flip Angle Settings | 7 | 7 | 7 |
| Total Time for this Series (min) | 18.2 | 21.0 | 8.61 |