[Establishment of a predictive model for central cervical lymph node metastasis of papillary thyroid carcinoma based on ACR TI-RADS score and evaluation of its diagnostic efficacy].

To establish a predictive model for central lymph node metastasis（CLNM） of papillary thyroid carcinoma（PTC） based on ACR TI-RADS grades（ATR model） and evaluate its diagnostic efficacy. A total of 319 patients with PTC diagnosed from January 2019 to May 2020 were included, including 366 nodules were used as the modeling cohort to construct the risk prediction model. A total of 105 PTC patients with 121 nodules from June to August 2020 were included as the external validation cohort. The C-index of the model was calculated and the Hosmer-Lemeshow goodness-of-fit test was performed to compare the diagnostic efficiency of ACR model and those conventional imaging models. The ATR model, Y=-3.719+0.765×gender+1.094×multifocality+0.08×maximum diameter+0.266×ACR TI-RADS score. In the training set, validation set and external validation cohort, the model C-index was 0.758（95%: 0.699-0.817）, 0.717（95%: 0.619-0.815） and 0.756（95% 0.671-0.840）, respectively. The Hosmer-Lemeshow goodness of fit test showed that the prediction rate of the model was consistent with the actual incidence rate（=0.918; =0.581; =0.366）. With ≥0.434 as the diagnostic threshold, the model had the highest diagnostic efficacy （sensitivity: 86.0%, specificity: 56.3%, Youden index: 0.423）. In the external validation cohort, there was no significant difference between C-US and CT（>0.05）. Compared with C-US and CT, the sensitivity（66.1% vs 16.1%, <0.001; 66.1% vs 9.7%, <0.001） and accuracy（68.6% vs 55.4%, =0.041; 68.6% vs 52.9%, =0.012） of ATR model were higher, and the negative predictive value was higher than that of CT（66.7% vs 50.9%, =0.042）, but there was no difference between ATR model and C-US（66.7% vs 52.3%, =0.066）; There was no significant difference among the three positive predictive values（70.7% vs 83.3%, =0.211; 70.7% vs 85.7%, =0.319）, but the specificity of the model was low （71.2% vs 96.6%, =0.001; 71.2% vs 98.3%, <0.001）. The predictive model based on ACR TI-RADS grades can predict CLNM of PTC more accurately and sensitively than traditional imaging examination.