Table 3.
Estimated sample sizes (95% CI) per arm using whole brain annualized PBVC (80% power at the 5% significance level to detect 25% reduction in disease progression) with and without controlling for normal aging calculated from manual-KN-BSI, STEPS-KN-BSI, pBSI1, pBSIγ, and gBSI for ADNI
| Manual-KN-BSI | STEPS-KN-BSI | pBSI1 | pBSIγ | gBSI | |
|---|---|---|---|---|---|
| 1.5 T | |||||
| Based on AD atrophy rates alone (N = 133) | 76 (58–100) | 71 (53–96) | 68 (51–93) | 75 (56–99) | 66 (50–90) |
| Controlling for normal aging (N = 328) | 211 (142–340) | 203 (137–327) | 185 (125–285) | 197 (135–301) | 183 (123–284) |
| 3 T | |||||
| Based on AD atrophy rates alone (N = 24) | 81 (37–162) | 82 (40–158) | 84 (40–162) | 86 (41–171) | 82 (40–159) |
| Controlling for normal aging (N = 63) | 194 (70–854) | 179 (72–675) | 180 (70–644) | 161 (61–573) | 179 (69–629) |
| Comparison | Percentage difference of sample size (95% CI), p-value |
|
|---|---|---|
| 1.5 T | 3T | |
| Manual-KN-BSI versus STEPS-KN-BSI | ||
| AD rates alone | −6.6 (−13.4 to 0.6), >0.05 | 1.4 (−10.9 to 20.1), >0.05 |
| Controlling for aging | −3.8 (−13.2 to 6.4), >0.05 | −0.8 (−29.1 to 15.9), >0.05 |
| Manual-KN-BSI versus gBSI | ||
| AD rates alone | −12.1 (−18.8 to −5.0), <0.05 | −1.7 (−10.8 to 20.6), >0.05 |
| Controlling for aging | −13.3 (−21.6 to −4.2), <0.05 | −7.5 (−28.9 to 16.6), >0.05 |
| STEPS-KN-BSI versus gBSI | ||
| AD rates alone | −6.5 (−10.6 to −2.3), <0.05 | −0.3 (−3.3 to 3.3), >0.05 |
| Controlling for aging | −9.8 (−16.0 to −3.5), <0.05 | 0.0 (−4.8 to 4.3), >0.05 |
| pBSI1 versus gBSI | ||
| AD rates alone | −2.4 (−5.0 to 0.6), >0.05 | −3.2 (−6.6 to 1.2), >0.05 |
| Controlling for aging | −1.0 (−4.4 to 3.0), >0.05 | −0.6 (−6.5 to 5.2), >0.05 |
| pBSIγ versus gBSI | ||
| AD rates alone | −10.7 (−15.2 to −5.8), <0.05 | −4.8 (−13.6 to 9.0), >0.05 |
| Controlling for aging | −7.0 (−12.5 to −1.1), <0.05 | 1.1 (−6.0 to 35.2), >0.05 |
Key: AD, Alzheimer's disease; ADNI, Alzheimer's Disease Neuroimaging Initiative; BSI, boundary shift integral; CI, confidence interval; gBSI, generalized boundary shift integral; PBVC, percentage brain volume change.