Table 1.
The DESS-MS sequence served as the morphometry reference sequences while the DESS-T2S served as the relaxometry reference sequence. A multi-echo fast-spin-echo sequence with eight echoes was also used for T2 comparisons (*meniscus T2 measurements utilized TEs of 6ms, 13ms, 19ms, and 26ms while cartilage T2 mapping utilized additional TEs of 32ms, 38ms, 45ms, and 51ms). All DESS sequences had a spoiler gradient area of 31.3 mT1m−1ms1 (1.33 cycles of dephasing/mm) and the minimum achievable TE and TR for the specified resolution and bandwidth. Note that for the clinical implementation of DESS-EXP, a readout of 416 samples and a slice thickness of 1.6mm was used to automatically reconstructed 512x512 images and to interpolate 0.8mm thick slices to 2.4mm thicknesses. Abbreviations: RO = readout, PE = phase encodes.
| # | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Sequence | DESS | DESS | ME-FSE | DESS |
| Purpose | Morphometry Standard | T2 Standard | T2 Comparison | Test Experimental |
| Shorthand Name | DESS - MS | DESS - T2S | ME-FSE | DESS - EXP |
| Matrix (RO × PE) | 512×512 | 256×256 | 128×128 | 384×512 |
| Resolution (mm2) | 0.31×0.31 | 0.62×0.62 | 1.25×1.25 | 0.42×0.31 |
| Slice Thickness (mm) | 1.5 | 3 | 3 | 1.5 |
| Number of Slices | 80 | 40 | 20 | 80 |
| TE S+ (ms) | 6.5 | 5.1 | N/A* | 5.7 |
| TE S− (ms) | 35.5 | 25.5 | N/A* | 30.1 |
| Number of Echoes | 2 | 2 | 8 | 2 |
| TR (ms) | 21 | 15.3 | 1650 | 17.9 |
| Flip Angle (°) | 20 | 20 | 90 | 20 |
| Bandwidth (± kHz) | 42 | 31 | 31 | 42 |
| Parallel Imaging | None | None | None | 2x1 |
| % Corners Cut | 0 | 0 | 0 | 25 |
| Scan Time (mm:ss) | 14:20 | 2:37 | 2:30 | 4:48 |