Factors Affecting The Accuracy Of Ultrasound-guided Fine Needle Aspiration Cytology Diagnosis Of Thyroid Nodules

Objective:To explore the factors affecting the diagnostic accuracy of fine needle aspiration cytology of thyroid nodules guided by ultrasound,so as to provide theoretical basis for improving the diagnostic accuracy.Methods:This study retrospectively analyzed 483 patients with 542nodules who underwent US-FNAC and surgery in the Ultrasound Department of Hebei General Hospital from March 2017 to September 2020.Taking the postoperative pathological results as the gold standard,the sensitivity,specificity,accuracy,false positive rate and false negative rate of US-FNAC diagnosis of thyroid nodules were calculated.The ultrasonic characteristics of thyroid nodules that may affect the diagnostic accuracy of US-FNAC were analyzed by univariate analysis,and then the significant influencing factors were analyzed by multi-factor Logistic regression analysis.Chi-square test or Fisher accurate test was used to test the difference of US-FNAC puncture times in sample deficiency rate and sample bleeding rate.The correlation between needle sensation and postoperative pathological results of Bethesda III thyroid nodules（Atypia of undetermined significance or follicular lesion of undetermined significance,AUS/FLUS）was accurately tested by Fisher.Results:1.Univariate analysis of ultrasonic features that may affect the accuracy of US-FNAC showed that the accuracy of US-FNAC was related to the diameter of thyroid nodules（P<0.05）,the composition of thyroid nodules（P=0.028）and the blood supply of thyroid nodules（P=0.001）,but not by calcification（P=0.728）and nodule position（P=0.520）.The results of multivariate Logistic regression analysis showed that the diameter of thyroid nodules≥4cm（P<0.05）,cystic-solid thyroid nodules（P=0.044）and hypervascular thyroid nodules（P=0.006）were independent factors affecting the accuracy of US-FNAC.2.The difference of US-FNAC puncture times in sample deficiency rate and sample bleeding rate was compared.The results showed that the difference was statistically significant（sample deficiency rate P=0.029&sample bleeding rate P=0.001）.The sample deficiency rate of 2 times of puncture was higher than that of 3 times and 4 times of puncture(P_2,3=0.03,P_2,4=0.043).The bleeding rate of samples with puncture times≥5 times was higher than that of samples with puncture times of 2 times,3 times and 4 times respectively(P_2,≥5=0.014,P_3,≥5=0.004,P_4,≥5=0.006).3.The accurate results of Fisher test showed that there was a significant correlation between needle sensation and postoperative pathology of AUS/FLUS（P<0.05）.90.0%of the nodules with grade 0 needle sensation were benign after operation,and 75.0%and 88.9%of the nodules with grade 1and grade 2 needle sensation were malignant,respectively.Conclusions:The results showed that thyroid nodule diameter≥4cm,cystic-solid nodule,hypervascular nodule,US-FNAC puncture times,needle sensation and AUS/FLUS were related to the accuracy of US-FNAC of thyroid nodule.Therefore,in the process of puncture,the operator should combine the ultrasonic characteristics of thyroid nodules and optimize the puncture process to ensure the adequacy of sampling.Thyroid nodules diagnosed as AUS/FLUS by FNAC for the first time should be combined with needle sensation.Repeated puncture or combined gene detection should be performed for those nodules with stiff needle or hard needle with gravel sensation,so as to further clarify the nature of thyroid nodules,so as to reduce the proportion of AUS/FLUS and improve the accuracy of US-FNAC of thyroid nodules.