Table 2.
Inter-observer reliability of MRI measurements from identical source images for both summary measures and individual muscle ROI values
| Measure | 1st observer group (mean ± SD) | 2nd observer group (mean ± SD) | ICC | Limits of agreement | n |
|---|---|---|---|---|---|
| Thigh level—overall mean for each subject | |||||
| Fat fraction (%) | 1.33 ± 0.50 | 1.24 ± 0.41a | 0.93 | -0.39 to +0.21 | 15 |
| T1 (ms) | 1,293 ± 33 | 1,287 ± 34 | 0.95 | -26 to +14 | 15 |
| T2 (ms) | 41.97 ± 2.20 | 42.01 ± 2.22 | 0.98 | -0.93 to +1.00 | 15 |
| MTR (p.u.) | 32.29 ± 1.37 | 32.34 ± 1.27 | 0.99 | -0.49 to +0.59 | 15 |
| Calf level—overall mean for each subject | |||||
| Fat fraction (%) | 1.54 ± 0.65 | 1.51 ± 0.57 | 0.95 | -0.41 to +0.33 | 15 |
| T1 (ms) | 1,275 ± 63 | 1,276 ± 66 | 0.99 | -23 to +24 | 14 |
| T2 (ms) | 39.89 ± 1.75 | 39.75 ± 1.79 | 0.96 | -1.08 to +0.80 | 15 |
| MTR (p.u.) | 32.75 ± 0.57 | 32.84 ± 0.56 | 0.95 | -0.25 to +0.43 | 15 |
| Thigh level—individual ROI values | |||||
| Fat fraction (%) | 1.32 ± 0.91 | 1.23 ± 0.91a | 0.79 | -1.04 to +1.22 | 281 |
| T1 (ms) | 1,289 ± 88 | 1,284 ± 94 | 0.93 | -62 to +72 | 221 |
| T2 (ms) | 41.96 ± 3.19 | 42.00 ± 3.61 | 0.84 | -3.82 to +3.75 | 280 |
| MTR (p.u.) | 32.36 ± 1.80 | 32.34 ± 1.91 | 0.90 | -1.59 to +1.63 | 248 |
| Calf level individual ROI values | |||||
| Fat fraction (%) | 1.55 ± 0.97 | 1.50 ± 0.98 | 0.83 | -1.08 to +1.17 | 172 |
| T1 (ms) | 1,269 ± 81 | 1,269 ± 81 | 0.95 | -48 to +50 | 138 |
| T2 (ms) | 39.89 ± 2.60 | 39.75 ± 2.69 | 0.86 | -2.59 to +2.88 | 180 |
| MTR (p.u.) | 32.76 ± 1.36 | 32.83 ± 1.31 | 0.92 | -1.15 to +1.00 | 175 |
Limits of agreement are calculated ± 1.96 SD by Bland-Altman method
ICC intra-class correlation coefficient
a Evidence of systematic difference between scans/observers (p < 0.001, Bland-Altman method)