The anteroposterior diameter of nodules in the risk assessment of papillary thyroid microcarcinoma

This study investigates the application of ultrasound, especially the anteroposterior diameter of nodules in the malignancy and metastasis risk assessment of papillary thyroid microcarcinoma through a retrospective analysis of 500 cases of thyroid nodule ultrasonography. We selected 500 patients with thyroid nodules (maximum nodule diameter ≤2.0 cm) that had been diagnosed clinically and graded TI-RADS 4c by ultrasonography and surgically treated. Among these, there were 258 cases of pathologically diagnosed papillary thyroid microcarcinoma, 72 cases of nodular goiter or adenoma, 137 cases of papillary thyroid carcinoma, 28 cases of acinar cell carcinoma, and 5 cases of undifferentiated carcinoma. In all cases, color Doppler ultrasonography had been performed preoperatively to determine the size and number of nodules, surrounding lymph node metastasis, and TI-RADS grading. Cases of papillary thyroid microcarcinoma diagnosed by pathology were selected as the study group, and cases of nodular goiter or adenoma as the control group. Each group was further subdivided based on the anteroposterior, vertical, and transverse nodule diameters. Intergroup statistical analysis was also performed. Receiver operating characteristic (ROC) curve analysis was conducted on the study and control groups based on the anteroposterior nodule diameters, and the optimal critical value for malignancy risk was determined. Thyroid nodules in the study group were divided into groups based on the presence or absence of lymph node metastasis. Based on the anteroposterior nodule diameter, ROC curve analysis was performed, and the optimal critical value for metastasis risk was determined. There were 500 cases of malignant nodules diagnosed by ultrasound. Among these, there were 428 cases of malignant nodules diagnosed by pathology. The coincidence rate of the ultrasound diagnosis with pathological diagnosis was 85.60%. While, interestingly, There was a significant statistical difference between the study and control groups based on the anteroposterior nodule diameter. When the anteroposterior nodule diameter was 0.7 cm, sensitivity of malignant diagnosis was 76.70% and specificity of that was 66.70%, and the Youden index was the highest. The lymph node metastasis rate for papillary thyroid microcarcinoma was 13.95%. Within this group, the lymph node metastasis rate for nodules ≥0.9 cm (anteroposterior diameter) was 38.46%. When the anteroposterior nodule diameter was equal to 0.9 cm, sensitivity of diagnosis was 83.30%, and specificity of that was 77.80%, and the Youden index was the highest. The anteroposterior diameter of thyroid nodules is more suitable for assessing their malignancy with 0.7 cm, which can be used as the critical value. Nodules ≥ 0.7 cm require surgical treatment, and those <0.7 cm can be observed. An anteroposterior diameter of 0.9 cm can be used as the critical value for assessing the metastasis risk of malignant thyroid nodules. During surgery, the dissection of central cervical lymph nodes is required for nodules ≥0.9 cm.