Thyroid Imaging Reporting and Data System (TIRADS) Versus Thyroid Scan for Solitary Thyroid Nodules

Abstract
Background: Solitary Thyroid nodules are a common finding which is defined as localized thyroid enlargement within an otherwise apparently normal gland. It is more common in females. Most of them are asymptomatic usually accidently discovered in neck US or carotid Doppler. Solitary thyroid nodule has a higher risk for malignancy than multiple nodules as reported in literature. Previously Radioactive Isotope scanning was first line for characterization before FNAC which is the gold standard to exclude malignancy. The availability and safety of US in addition to marvelous technological advances that yields high diagnostic power made it a prefect tool for the initial characterization of thyroid nodules. Recently TI-RADS (Thyroid Imaging Reporting and Data System) were proposed on the basis of ultrasound features for initial Solitary thyroid nodule characterization.
Aim of Study: To compare between Thyroid Imaging Reporting and Data System and thyroid scan to evaluate the malignant potentiality of the solitary thyroid nodule with taking reference the results of fine needle aspiration cytology (FNAC) and histopathology as gold standard.
Material and Methods: Thirty patients were enrolled in our cross section study with solitary thyroid nodule referred from the Otolaryngology Department to Radiology Department at Ain Shams University Hospitals. All patients underwent full thyroid ultasound examination with full comment on the nodules as regarde shape, echogenicity, margins, internal components and echogenic foci and classified according to the Americal college of radiology (ACR) Thyroid Imaging Reporting and Data System (TIRADS) Classification guideline, then thyroid scan was done to all cases. Results of both ultrasound and thyroid scan are compared with histopatholog-ical results of Fine needle aspiration cytology (FNAC).
Results: The sensitivity and specificity of TIRADS on considering TR4 and TR5 lesions positive ( suspiciuos) when compared with histopathological findings were 100% and 79.2% respectively with PPV of 54.5%, NPV of 100% and accuracy of 83.3%. While isotope sensitivity when considering a cold nodule to be positive (suspiciuos) was 66.7% with specificity of 16.7%, PPV of 20%, NPV of 66.7% and accuracy of 26.7%.
Conclusion: Our results suggest that ACR TIRADS clas-sification is superior to thyroid scan as regarde charchterization of solitary thyroid noude and considered reliable in predicting thyroid malignancy.