〔Abstract〕 Objective To analyze the value of accruate quantitative SPECT/CT in differential diagnosis of benign and malignant thyroid nodules. Methods 81 patients with thyroid nodules diagnosed by ultrasound were selected.All patients were examined by99mTcO4-imaging and quantitative SPECT/CT,cool and cold nodules were performed99mTc-MIBI imaging and quantitative SPECT/CT on the next day. Region of interest( ROI) was used to obtain thyroid uptake rate and nodule's standard uptake value. The difference between the parameters of benign and malignant nodules was compared based on patient's postoperative pathology. The diagnostic thresholds of standardized uptake value( SUV) were obtained by drawing the ROC curves,and the diagnostic efficacy was evaluated by comparing with the results of99mTcO4-and99mTc-MIBI imaging. Results In 81 patients,postoperative pathology showed that 35 thyroid nodules were malignantand 46 thyroid nodules were benign. The difference of thyroid uptake rate and nodule's standard uptake value between benign and malignant groups was statistically significant( P<0. 05).The diagnostic sensitivity,specificity and accuracy of99mTcO4-combined with99mTc-MIBI imaging were 41. 6%,68. 8%,56. 8% respectively. ROC curve results showed the diagnostic thresholds,area under curve( AUC),sensitivity,specificity,accuracy of99mTcO4-SUVmax and SUVavg were 43. 83 g/ml,0. 808,100%,51. 1%,72. 8% and30. 08 g/ml,0. 808,94. 1%,57. 4%,74. 1% respectively. The diagnostic thresholds,AUC,sensitivity,specificity,accuracy of99mTc-MIBI SUVmax and SUVavg were 2. 24 g/ml,0. 899,79. 4%,92. 9%,85. 4% and 1. 37 g/ml,0. 816,88. 2%,71. 4%,82. 2% respectively. Conclusion Accurate quantitative SPECT/CT has high accuracy in diagnosis of benign and malignant thyroid nodules,and99mTc-MIBI SUVmax has the highest diagnostic efficiency when the diagnostic threshold is 2. 24 g/ml.