Results of ROC analysis of DWIs at b = 1000 and b = 3000 s/mm2
| DWI | Az* | Cutoff Score† | Sensitivity (%) | Specificity (%) | PPV‡ (%) | NPV‡ (%) | κ-value§ |
|---|---|---|---|---|---|---|---|
| b = 1000 s/mm2 | 0.790 | 5 | 69.4 | 76.9 | 94.4 | 40.0 | 0.56 |
| b = 3000 s/mm2 | 0.864 | 4 | 83.7 | 84.6 | 95.3 | 57.9 | 0.77 |
Note:—ROC indicates receiver operating characteristic; DWI, diffusion-weighted imaging.
* Az refers to area under the ROC curve; these were not significantly different with the 2 b-values (P = .08).
† Cutoff score refers to the optimal cutoff level for high-grade glioma with highest accuracy for obtaining a positive test for high-grade glioma with a minimum C1 error by ROC analysis, where C1 = 1 − (sensitivity+specificity)/2.
‡ PPV and NPV are positive and negative predictive values, respectively, for high-grade glioma.
§ κ-value is the kappa value for interobserver agreement.