Parameters used in both conventional and ultrafast MR sequences
| Sequence | Conventional T1 | ASSET T1 | Conventional T2 | ASSET T2 | Conventional FLAIR | ASSET FLAIR | Conventional DWI | ASSET DWI | Conventional MRA | ASSET MRA |
|---|---|---|---|---|---|---|---|---|---|---|
| Spin echo | Fast spoiled GRE | Fast spin echo | Fast spin echo | FLAIR | IR single shot fast spin echo | Spin echo EPI | Spin echo EPI | 3D ToF | 3D ToF | |
| ASSET, array spatial sensitivity encoding technique (GE Medical Systems implementation of sensitivity encoding; note that all ASSET acquisitions were carried out using an in-plane (that is, phase encoding direction) scan reduction factor of 2); ETL, echo train length; FLAIR, fluid attenuated inversion recovery; FOV, field of view; NEX, number of excitations (signal averages); RBW, receiver bandwidth; TE, time of echo time; TI, time of inversion; TR, time of repetition. | ||||||||||
| Plane | Axial | Coronal | Axial | Axial | Axial | Axial | Axial | Axial | Axial | Axial |
| TE (ms) | 9 | 4.2 | 102 | 100 | 160 | 121 | Min (76.4) | Min (66.8) | 6.9 | Min (3.1) |
| TR (ms) | 600 | 250 | 6000 | 5800 | 8000 | Min (2181) | 10000 | 4925 | 42 | 20 |
| TI (ms) | – | – | – | – | 2200 | 2000 | – | – | – | – |
| ETL/No of shots | – | – | 24 | 24 | NA | – | 1 | 1 | – | – |
| Flip angle (°) | – | 75 | – | – | – | – | – | – | 20 | 20 |
| RBW (kHz) | 15.6 | 15.6 | 20.8 | 20.8 | 31.2 | 41.7 | 250 | 250 | 31.2 | 31.25 |
| FOV (cm) | 24 | 26 | 22 | 24 | 22 | 24 | 28 | 28 | 22 | 24 |
| Phase FOV | 1.0 | 1.0 | 0.75 | 0.75 | 1.0 | 0.7 | 0.8 | 1.0 | 0.75 | 1.0 |
| Slice thick (mm) | 5 | 5 | 6 | 6 | 6 | 6 | 5 | 5 | 1.4 | 2 |
| Slice spacing (mm) | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | −0.7 | −1.5 |
| No of slices | 22 | 20 | 20 | 20 | 20 | 20 | 28 | 28 | 48 | 26 |
| Matrix frequency | 256 | 256 | 320 | 320 | 256 | 256 | 128 | 128 | 512 | 320 |
| Matrix phase | 224 | 192 | 256 | 224 | 224 | 128 | 128 | 128 | 256 | 192 |
| NEX | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.68 | 2.0 | 1.0 | 1.0 | 1.0 |
| Scan time (min:s) | 02:23 | 00:26 | 00:54 | 00:29 | 02:41 | 00:44 | 1:20 | 00:39 | 06:31 | 00:54 |