Table 3:

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.