Table 2.
Estimated parameters (mean ± SD) of observed T1 and the two-pool quantitative MT model for the five clusters. T1,obs is the observed longitudinal relaxation time. T2,A and T2,B are the transverse relaxation times of the liquid and macromolecular pools, respectively. R is the magnetization exchange rate from the semisolid macromolecular to liquid pools. M0,B is the macromolecular pool size relative to that of water (defined to be unity). The product of R and M0,B, termed MT effect, is presented because these two parameters are coupled. Blood/edema is expected to have a relatively small MT pool size41, which is reflected in the large uncertainties in MT effect and T2,B. All parameters were estimated for individual mice before averaging. Any given cluster per mouse was included only if it contained at least seven voxels.
| Cluster | T1,obs (ms) | T2,A (ms) | MT Effect | T2,B (µs) |
|---|---|---|---|---|
| Active tumour (n = 34) | 2200 ± 100 | 53 ± 6 | 1.2 ± 0.1 | 8.2 ± 0.3 |
| Necrosis/apoptosis (n = 10) | 2600 ± 100 | 80 ± 9 | 1.1 ± 0.3 | 7.8 ± 0.2 |
| Blood/edema (n = 8) | 2800 ± 300 | 130 ± 60 | 0.9 ± 0.8 | 100 ± 100 |
| Muscle/connective (n = 11) | 1810 ± 80 | 31 ± 6 | 1.5 ± 0.5 | 7.4 ± 0.4 |
| Muscle (n = 31) | 1840 ± 80 | 27 ± 2 | 3.8 ± 0.5 | 7.2 ± 0.2 |