Table 2.
Tissue parameters used to generate the synthetic spinal cord scans. Values are inspired by previous literature (Battiston et al., 2018a; Grussu et al., 2015; Smith et al., 2008). For white/grey matter, within-tissue variability was simulated by drawing parameter values from a Gaussian distribution and assigning the obtained values to different voxels. The mean and standard deviation of the Gaussian distributions are reported in the table (standard deviation within brackets, equal to 10% of the mean). For the cerebrospinal fluid (CSF), tissue parameters were fixed to the same values across all CSF-containing voxels.
|
Tissue |
Relative proton density ρ |
Longitudinal relaxation time T1 [ms] |
Transverse relaxation time T2 [ms] |
Axial diffusivity AD [μm2/ms] | Radial diffusivity RD [μm2/ms] | Free-to-bound proton exchange rate k [1/s] | Free proton transverse relaxation time T2F [ms] | Bound proton transverse relaxation time T2B [μs] | Bound pool fraction BPF |
|---|---|---|---|---|---|---|---|---|---|
| White matter | 0.70 (0.07) | 1000 (100) | 70 (7) | 2.10 (0.21) | 0.40 (0.040) | 2.3 (0.23) | We fix T2F = T2 |
12 (0.12) | 0.14 (0.014) |
| Grey matter | 0.80 (0.08) | 1200 (120) | 80 (8) | 1.60 (0.16) | 0.55 (0.055) | 1.7 (0.17) | We fix T2F = T2 |
12 (0.12) | 0.08 (0.008) |
| CSF | 1.00 | 4000 | 800 | 3.00 | 3.00 | Not defined (BPF = 0) | We fix T2F = T2 |
Not defined (BPF = 0) | 0.00 |