Accurate Quantitative SPECT/CT For Differential Diagnosis Of Benign And Malignant Thyroid Nodules

ObjectiveAnalysis and explore the diagnostic ability of quantitative SPECT/CT for benign and malignant thyroid nodules and its advantages over traditional planar imaging.MethodsPatients with thyroid nodules diagnosed by ultrasound from March 2019 to August 2020were selected（TI-RADS grade 4a and above）.T3,T4,FT3,FT4,TSH level and iodine uptake rate were measured in enrolled patients.99m TcO4ˉstatic imaging was performed the next day to obtain thyroid uptake rate and SPECT/CT tomography fusion imaging was conducted to acquire nodule’s standard uptake value.The imaging results were interpreted by the senior deputy chief physician.Cool nodules and cold nodules were performed 99m Tc-MIBI imaging and SPECT/CT tomography fusion imaging on the next day.Drawing ROI to get nodule’s SUVmax and SUVavg.Using Pearson test to analyze the correlation between SUV values and the above hormone levels,iodine uptake and uptake rate.The differences of parameter values were compared between benign and malignant nodules based on the results of pathological diagnosis.The diagnostic thresholds of SUVmax and SUVavg were obtained by drawing ROC curve,and the diagnostic efficacy was evaluated by comparing with the results of 99m TcO4ˉstatic imaging and 99m Tc-MIBI dual-phase imaging.Results1.The difference between benign nodules and malignant nodules had no statistical significance in hormone levels,nodule size,sex and age,iodine uptake rate,and significant difference in thyroid uptake rate,99m TcO4ˉSUVmax,99m TcO4ˉSUVavg,99m Tc-MIBI SUVmax and 99m Tc-MIBI SUVavg（p<0.05）.2.99m TcO4ˉSUVmax（r=0.488,p<0.001）and 99m TcO4ˉSUVavg（r=0.460,p<0.001）showed positive correlation with thyroid uptake rate.99m Tc-MIBI SUVmax and99m Tc-MIBI SUVavg have no correlation with the above hormone levels,iodine uptake rate and uptake rate（p>0.05）.3.99m TcO4ˉstatic imaging showed 19 hot nodules,31 cool nodules,31 cold nodules.Hot nodules were all benign,18 cool nodules and 9 cold nodules were benign.The remaining 35 patients were malignant.99m Tc-MIBI dual phase delay results showed that 8 cases out of 31 cool nodules had radioactive concentration and the rest cases had no radioactive concentration.In 31 cold nodules,21 cases had radioactive concentration,10 cases had no radioactive concentration.Among 29 cases of radioactive concentration,15 were malignant.Among 33 cases without radioactive concentration,20 were malignant.The remaining 27 cases were benign.Combined 99m TcO4ˉand99m Tc-MIBI imaging,the sensitivity,specificity and accuracy were 41.6%,68.8%and56.8%respectively.4.The ROC curve showed the diagnostic thresholds,AUC,sensitivity,specificity and accuracy of 99m TcO4ˉSUVmax and SUVavg were 43.83g/ml,0.808,100%,51.1%,72.8%and 30.08g/ml,0.808,94.1%,57.4%,74.1%respectively.The diagnostic thresholds,AUC,sensitivity,specificity and accuracy of 99m Tc-MIBI SUVmax and SUVavg were 2.24g/ml,0.899,79.4%,92.9%,85.4%and 1.37g/ml,0.816,88.2%,71.4%,82.2%respectively.The diagnostic efficacy of standard uptake values was better than traditional planar imaging.ConclusionAccurate quantitative SPECT/CT has high accuracy in diagnosis of benign and malignant thyroid nodules,^99mTc-MIBI SUVmax has the highest diagnostic efficiency when the diagnostic threshold is 2.24g/ml.