Utilities Of Thyroid Imaging Report And Data System In Thyroid Nodules On CT Scan

Objective:Study 1.To develop a new Thyroid Imaging Reporting and Data System(TIRADS)based on CT features,which could be used to categorize Incidental Thyroid Nodules found in CT scan.Study 2.To explore the clinic value of Anteroposterior to transverse diameter ratio(A/T)in differentiating benign and malignant thyroid nodules on CT Scan.Methods:Study 1.We included 183 thyroid nodules in 152 patients with neck CT data and thyroidectomy.Under blinded conditions for the histopathological results,two radiologists used a picture archiving and communication system(PACS)to review the images and recorded CT features of each thyroid nodules.X2 test was used to analyse the difference of7 CT features including composition(cystic or not),number(single or not),density(homogeneous or not),margins(regular or not),calcification(with or without),surrounding invasion and lymphatic metastasis between benign and malignant groups which were divided by pathological results.According to Kawk' s TIRADS,We designed a new TIRADS based on CT malignant features named CT-TIRADS.The rates of malignancy in different categories were counted and compared with Kawk's TIRADS and BI-RADS.ROC curves and Area under the ROC Curve were performed to compare the diagnostic value of CT-TIRADS and 6 malignant CT Features.Study 2.The data of 183 thyroid nodules same to Study 1 was used by two radiologists to measure anteroposterior diameter,transverse diameter,and A/T.Kruskal-Wallis Test was used to analyse the difference of anteroposterior diameter,transverse diameter and A/T between benign and malignant groups.ROC curves and Area under the ROC Curve were performed to compare the diagnostic value of A/T in differentiating benign and malignant thyroid nodules on CT Scan.We used ROC curves and Area under the ROC Curve to compare the diagnostic value of A/T and CT-TIRADS in differentiating benign and malignant thyroid nodules on CT Scan.A/T and CT-TIRADS were combined to differentiate benign and malignant thyroid nodules.Results:Study 1.The features of non-cysitc,single nodule,irregular margins,calcification,surrounding invasion and lymphatic metastasis were related to the malignant thyroid nodules.Risks of Category 1 to 3,4a to 4c,and 5 were separately 0%,0%,1.4%,12.2%,56.0%,75%,100%.The area under the ROC curve at CT-TIRADS was 0.919,lager than other each CT features.Study 2.Median and Standard Deviation of anteroposterior diameter in benign thyroids group were 18.0±9.7mm,in malignant group were 14.0±8.1mm.P value was0.032.Median and Standard Deviation of transverse diameter in benign thyroids group were 17.0±9.9mm,in malignant group were 11.4±6.6mm.P value was 0.001.Median and Standard Deviation of A/T in benign thyroids group were 1.0±0.2,in malignant group were 1.3±0.3.P value was 0.000.Area under the ROC Curve of A/T in differentiating benign and malignant thyroid nodules on CT Scan were 0.742.The best cutoff value of A/T was 1.2,Youden Index was 0.46,sensitivity was 61.8%,specificity was 84.6%.When cutoff value 1.0 was chosen like the Ultrasound feature,sensitivity was 79.4%,specificity was 51.0%.The best cutoff value of CT-TIRADS was 4b,Youden Index was 0.71,sensitivity was 79.4%,specificity was 91.3%.Combined A/T with CT-TIRADS,we differentiated benign and malignant thyroid nodules.Meanwhile,sensitivity was 50%,specificity was 98.7%,accuracy was 89.6%?Conclusion:Study 1.The new TIRADS based on CT features could accurately categorize the thyroid nodules found in CT scan.It would be useful to manage incidental thyroid nodules.Study 2.Like A/T?1.0 as a malignant sign in thyroid nodules used on Ultrasound TIRADS,A/T?1.2 could be used as a indicator of malignancy on CT Scan.CT-TIRADS had a better diagnostic value than A/T.Combined A/T with CT-TIRADS,higher specificity could be got in differentiating benign and malignant thyroid nodules.