Table 1.
Default scanner settings a for the seven sequences which were compared, with ranges for adjustable settings in parentheses b
| Sequence ID | A | B | C | D | E | F | G |
|---|---|---|---|---|---|---|---|
| Scan time (min:sec) | 3:13 | 2:16 | 3:46 | 4:03 | 8:12 | 6:24 | 2:23 |
| Sequence name | T1 FLAIR | DWI | 3D TOF | 3D FIESTA | T1 SE | FSPGR BRAVO | SWAN |
| Sequence type | 2D T1‐weighted fluid attenuation sequence with inversion recovery | 2D Diffusion weighted sequence | 3D Time‐of‐flight angiography sequence | 3D Balanced steady‐state gradient echo sequence | 2D T1‐weighted spin echo sequence | 3D Ultrafast spoiled gradient echo sequence | 3D Susceptibility enhanced angiography sequence |
| TR (ms) | 2707.4 | 9096 | 11 | 5 | 6000 | 8.9 | 54.4 |
| TE (ms) | 24 (1–2000) | 73.6 (73.6–207) | 2.6 (0.1–11) | 2.1 | 18 (18–20) | 3.5 | 24.3 (22.7–25) |
| TI (ms) | 827 (334–1244) | – | – | – | – | 450 (30–450) | – |
| FA (°) | 111 (1–147) | – | 15 (1–45) | 55 (1–90) | – | 12 (1–25) | 15 (1–50) |
| FOV frequency direction c (cm) | 22 (21–31.5) | 24 (13.6–60) | 22 (19.5–50) | 18 | 22 (22–50) | 26 | 20 |
| FOV phase direction (cm) | 19.8 | 21.6 | 16.5 | 16.2 | 19.8 | 26 | 20 |
| Acquisition matrix (Nf x Np) | 320 × 288 | 128 × 128 | 384 × 256 | 200 × 320 | 320 × 224 | 264 × 264 | 320 × 224 |
| BWr d (kHz) | 41.67 (41.67–142.86) | 250 | 62.5 | 62.5 | 31.25 (31.25–83.33) | 31.25 | 62.5 |
| Slice thickness (mm) | 4 (3.8–10.4) | 4.5 (4.5–20) | 0.8 (0.6–5.2) | 0.6 | 4 (1.1–10) | 1 (0.84.6) | 3 (0.8–3.1) |
| Slice spacing (mm) | 0.5 (0.1–7.1) | 0.4 (0.1–20) | – | – | 0.5 (0.1–20) | – | – |
| Number of slices (2D) or locations per slab (3D) | 32 | 32 | 104 | 98 | 30 | 244 | 48 |
| NEX | 2 | – | – | 1 | 2 | 1 | – |
| WB‐SAR e (W/kg) | 1.11 | 0.1 | 0.07 | 1.05 | 0.82 | 0.07 | 0.06 |
Initial sequence settings for repetition time (TR), echo time (TE), inversion time (TI), flip angle (FA), field of view (FOV) in the frequency‐encode direction and in the phase‐encode direction, acquisition matrix size (Nf = number of pixels in the frequency encode direction, and Np = number of pixels in the phase encode direction), receiver bandwidth (BWr), slice thickness, slice spacing, number of slices, and number of excitations (NEX) for sequences A‐G. Instances denoted with − indicate that the parameters were not adjustable or not part of those sequences.
The numbers in parentheses indicate the range allowed when changing one setting at a time without affecting any of the other settings or the total scan time. Default values without parenthesis indicate that a parameter was not variable in a given sequence, or that it was not possible to vary without affecting the total scan time.
FOV in the frequency‐encode direction was varied while keeping the acquisition matrix size (Nf) constant which means that the pixel size varied.
Receiver bandwidth values represent the frequency range around the nominal radiofrequency reception center frequency, so BWr = 250 kHz actually means ±250 kHz, that is, a frequency range of 500 kHz.
Whole‐body SAR (WB‐SAR) estimates were provided by the scanner before the start of the scan, and based on the fictitious data of a 35‐kg child instead of the 3‐liter phantom that was actually scanned.