Ultrasonography-based Stratification System Of Thyroid Nodules And Its Application In Clinical Practice

BackgrandThyroid nodule is a common disease in clinical practice. As one of fastest growing cancers, thyroid cancer has increased by2.4times in the past30years. At the same time, the incidence rates of all pathologicaltypes of thyroid cancer have steadily increased year by year. In Zhejiang province, the incidence rate has increase from5.98/100,000in2006to11.42/100,000in2009(the national average incidence is6.56/100,000) and was expected to continuously increase in the future. Because ultrasonography is superior to clinical examination in detecting manythyroid nodules, both American Thyroid Association (ATA) andBritish Thyroid Association (BTA) recommend applying ultrasonography to evaluate thyroid nodules and cervical lymph node. It provides important medical imaging evidence for clinical diagnosis before and after surgery.Although the accuracy of ultrasonography in diagnosing thyroid nodules could be as high as74%to82%, there is no established standard to evaluate malignancy of thyroid nodules. In addition, due to variety of ultrasonographic parameters and lack of standard in ultrasonographic reports, the description and diagnosis are not consistent and comparable among different hospitals and doctors. In recent years, several quantitative evaluation systems of ultrasonographic diagnosis are proposed. Harvath et al.(2009) firstly propose thyroid imaging reporting and data system (TI-RADS), which is defined by10ultrasonographic patterns (shape, orientation, echogenicity, echostructure, acoustic transmission, borders, surface, presence or absence of a capsule, calcifications, and vascularization) and6TI-RADS group classifications. Park et al.(2009) propose aTI-RADSfeatured by12aspects of thyroid nodules, such as shape, orientation, echogenicity, tissues, borders, calcifications, and surrounding lymph nodes. Zhou et al (2012) find that elastosonography performs better than TI-RADS in terms of diagnostic accuracy and that the joint diagnosis of these two methods is superior to either of them.In sum, the ultrasonography-basedstratification system of evaluating malignancy in thyroid noduleshas become a hot research problem. Based on previous research and clinical practice, this project is to establish a relatively complete stratified diagnostic model characterized by20ultrasonographic parameters and extend this model to computer software so as to quickly evaluate everythyroid nodule in clinical practice.Methods We retrospectively analyzed20ultrasound features of926thyroid nodules in527patients and calculated the OR value of each feature. Using logistic regression analysis, we obtained the probability function for predicting the malignancy in thyroid nodules and establish a preliminary classification system.Results The ages of patients with thyroid nodules were older than the patients with thyroid Carcinoma (t=6.496, P<0.001). The correctness ratio of ultrasonic diagnosis was80.13%. By applying both single-and multi-factor analysis, our study showed that, among all ultrasonography features, aspect ratio≥1, obscure boundary, irregular boundary, significant internal echo, internal echo, internal micro-calcifications, echo attenuation, thyroid capsule invasion, swelling lymph nodes, and ultrasonic elastography5-point evaluation>3, were contributing factors for thyroid Carcinoma. The equation was Pus=1/[l+e-z] where z is the logit of malignant thyroid nodule. Pus was stratified into four levels:Level1:0～16%malignancy; Level2:16～50%malignancy; Level3:50～71%malignancy; and Level4:71～100%malignancy. Conclusions Quantitative Thyroid Imaging Reporting and Data System makes ultrasound reports more objective and standardized. It can be used in clinical evaluation on malignant risk of thyroid nodules and help make right decision.