Interobserver reliability and precision of hippocampal FA and MD values (n = 20)
| 1st Investigator Mean ± SD (Range) | 2nd Investigator Mean ± SD (Range) | Diff ± SD | t value | r | rs | ICC | SEM | CI 95% | CV | R95 (%) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| FA left | 247 ± 26 | 243 ± 28 | 5 ± 13 | 1.58 | .89 | .87 | .93 | 9.5 | ±19 | 3.9% | 26 (10.8%) |
| (235–259) | (179–283) | ||||||||||
| FA right | 228 ± 20 | 230 ± 23 | −2 ± 14 | −0.63 | .78 | .86 | .88 | 10.1 | ±20 | 4.1% | 28 (12.2%) |
| (219–238) | (198–286) | ||||||||||
| FA mean | 238 ± 16 | 236 ± 20 | 1 ± 11 | 0.52 | .85 | .87 | .90 | 7.6 | ±15 | 3.1% | 21 (8.9%) |
| (230–245) | (195–279) | ||||||||||
| MD left | 782 ± 46 | 776 ± 28 | 5 ± 28 | .85 | .81 | .82 | .84 | 19.8 | ±39 | 2.5% | 55 (7.0%) |
| (760–803) | (728–821) | ||||||||||
| MD right | 769 ± 27 | 766 ± 23 | 3 ± 18 (25) | 0.68 | .75 | .79 | .85 | 12.9 | ±25 | 1.7% | 36 (4.6%) |
| (756–782) | (721–816) | ||||||||||
| MD mean | 775 ± 30) | 771 ± 23) | 4 ± 18 (27) | 1.02 | .81 | .90 | .87 | 12.7 | ±25 | 1.6% | 35 (.5%) |
| (761–790 | (733–817 |
Note.— FA indicates fractional anisotropy (×103); MD, mean diffusivity (μm2/s); Diff, difference of 1st assessment of first investigator (cf. Table 1, 1st column) and assessment of 2nd investigator ± SD of difference; t value, corresponding to paired t test, all P values >.10; r, Pearson correlation coefficient; rs, Spearman rank correlation coefficient; ICC, intraclass correlation coefficient; SEM, standard error of measurement based on within-subject variance; CI 95%, 95% confidence interval (±1.96 × SEM); CV = √(mean of within subject variance/mean squared); R95, repeatability according to Bland and Altman20: R95WSV = √2 × 1.96 × SEM; %, percentage of mean = R95/mean × 100.