GFAP and glioma: The two-marker (GFAP/FABP4) combination model performance was as follows: at 100% specificity (where all 70 meningiomas were correctly predicted to be meningiomas), the sensitivity for glioma detection was 53%, the positive predictive value (PPV) for meningioma detection was 1.00, the negative predictive value (NPV) was 0.54, and the accuracy was 70%.