Table 3.31.Diagnostic values of PET and PET / CT in detection of recurrent / metastatic thyroid cancer (n = 109) Modality Value PET PET / CT Sensitivity (%) 88.2 92.9 Specificity (%) 75 75 Positive predictive value (%) 92.6 92.9 Negative predictivevalue (%) 64.3 75 False positive rate (%) 25 25 Falsenegative rate (%) 11.2 7.1 Accuracy (%) 85.3 89 Remarks: - PET / CT had 92.9% sensitivity, 75% negative predictivevalue and 89% accuracy, higher than that of PET (88.2%; 64.1% and 85.3%, respectively).