Table 1.
The acquired sequences were 3D double-echo steady-state (DESS), 3D fast spin echo short-tau inversion recovery (SPACE-STIR), 3D fast spin echo spectral attenuated inversion recovery (SPACE-SPAIR), 3D volumetric interpolated breath-hold examination (T1-VIBE-Dixon), and 3D ultrashort echo time (UTE).
| DESS | T2 SPACE STIR | T2 SPACE SPAIR | T1 Vibe Dixon | UTE | |
|---|---|---|---|---|---|
| Sequence name | de_rr | spcir | spc | fl | WIP_fl |
| Geometry | |||||
| Dimension of acquisition | 3D | 3D | 3D | 3D | 3D radial |
| Orientation | semi-axial | semi-axial | semi-axial | coronal | semi-axial |
| Phase enc. dir. | R >> L | A >> P | A >> P | F >> H | A >> P |
| FoV read and phase [mm] | 242 × 242 | 190 × 190 | 190 × 190 | 380 × 212 | 230 × 230 |
| Slices per slab | 104 | 120 | 120 | 96 | 384 |
| Acq. slice thickness [mm] | 0.75 | 0.75 | 0.75 | 1.00 | 0.6 |
| Phase/slice oversampling | 0%/100% | 35%/20% | 35%/20% | 40%/67% | – |
| Acq. matrix read/phase | 320 × 320 | 256 × 256 | 256 × 256 | 380 × 380 | 384 × 384 |
| Radial views | – | – | – | – | 40’000 |
| Voxel recon size [mm3] | 0.38×0.38×0.75 | 0.37×0.37×0.75 | 0.37×0.37×0.75 | 0.8×0.8×1.0 | 0.6×0.6×0.6 |
| Contrast | |||||
| Flip angle [degree] | 30 | T2 var | T2 var | 11 | 5 |
| Echo spacing [ms] | – | 4.82 | 4.82 | – | – |
| Echo train duration [ms] | – | 284 | 284 | – | – |
| TR [ms] | 11.16 | 3300 | 3300 | 5.81 | 4.62 |
| TE [ms] | 4.21 | 113 | 115 | 2.46/3.69 | 0.04 |
| Magn. preparation | off | Non-sel. IR | None | – | – |
| TI [ms] | – | 220 | – | – | – |
| Fat suppr. | Water excit. normal | None | SPAIR, strong | Dixon,optim inphase | None |
| Duration | |||||
| TA [min:s] | 12:24 | 12:36 | 12:36 | 05:28 | 03:07 |
| Averages | 1 | 1.4 | 1.4 | 1 | 1 |
| PAT total accel. factor | Off | 4 | 4 | Off | 0 |
| PAT mode | – | GRAPPA phase 2, ref.l. 24 slice 2, ref.l. 24 | GRAPPA phase 2, ref.l. 24 slice 2, ref.l. 24 | – | – |
| Asymmetric echo | Off | – | – | weak | strong |
| Bandwidth [Hz/Px] | 355 | 425 | 425 | 660/700 | 1184 |
| Artifact reduction | |||||
| Flow comp. | Read | No | No | – | – |
| Excitation | Slab-sel. | Slab-sel. | Slab-sel. | Slab-sel. | Non-sel. |
| RF spoiling | – | – | – | On | On |
| Incr. gradient spoiling | – | – | – | On | On |
| Distortion corr. | 2D | 3D | 3D | 3D | – |
Two fat saturation methods (STIR and SPAIR) for the SPACE sequence were compared, but all other parameters were kept equal. All sequences were acquired with sub-millimetric isotropic resolution and optimized for quality in a pilot study. Detailed sequence parameters are provided.