Table 1.
Image acquisition protocol
| TR/TE (ms) | Voxel size (mm3) | Acquisition matrix | Reconstruction matrix | Receiver bandwidth Hz/px | Flip angle | b-values (s/mm2) | Tumour coverage | |
|---|---|---|---|---|---|---|---|---|
| Pre-contrast | ||||||||
| High resolution 2-point 3D GRE DIXON | 7/3.69 | 1.25 × 1.25×2 | 192 × 154 | 192 × 192 | 605 | four o/16o | N/A | Full |
| DW-EPI | 11200/77 | 1 × 1×4 | 128 × 104 | 208 × 256 | 2055 | 90o | 50, 300, 600, 900 | Full |
| 2D multi echo GRE | 100/10 echo times (range 4.9–68.9) | 1.5 × 1.5×3 | 160 × 160 | 160 × 160 | 490 | 45 | N/A | Central volume |
| Post-contrast | ||||||||
| DCE-MRI 2-point 3D GRE DIXON | 5.74/2.46 | 1.5 × 1.5×3 | 160 × 141 | 160 × 160 | 600 | four o/16o | N/A | Central volume |
| High resolution 2-point 3D GRE DIXON | 7/3.69 | 1.25 × 1.25×2 | 192 × 154 | 192 × 192 | 605 | four o/16o | N/A | Full |
DCE-MRI, Dynamic contrast enhanced-MRI; DW-EPI, diffusion weighted echoplanar imaging; GRE, Gradient echo.
DWI, 2D multiecho GRE and DCE-MRI sequences were centered on a slice chosen by a specialist sarcoma radiologist to ensure targetingthe section of the tumour with increased cellularity and to avoid areas of high fat content.
DCE-MRI comprised 85 dynamic acquisitions with time resolution 3 s with the highest flip angle (16o) [a gadolinium based contrast administration (2 ml s−1 followed by 20 ml saline flush)]