FIG 5. ROC analysis showing effect of using each individual variable or the discriminant function (C1) in differentiating between high- and low-grade tumors. The area under the ROC curve for high- versus low-grade is greatest for the discriminant function (0.993). Within the independent parametric variables the area was highest for K^trans (95%) (0.986), though similarly high values were seen for K^trans and CBV (0.979 and 0.966, respectively). (Areas under the ROC curves are shown in Table 7.)