Application of society of radiologists in ultrasound recommendations for fine needle aspiration of thyroid nodules

Background: The Society of Radiologists in Ultrasound (SRU) recommendations on thyroid nodules are intended to “diagnose thyroid cancers that have reached clinical significance,while avoiding unnecessary tests and surgery in patients with benign nodules.” Methods: This prospective observational study was conducted on 193 consecutive patients undergoing ultrasonography (USG) guided thyroid FNA. Nodules were categorized as “SRU-positive”and “SRU-negative” based on USG features. The sensitivity and specificity of the SRU recommendations and of various US features for thyroid malignancy were calculated. Results: Of 193 patients subjected to FNA, 83 patients of Bethesda class I,III,IV,V were excluded. Among 110 nodules subjected to FNA, 79 were SRU positive and 31were SRU negative. There were 24 malignancies in 110 FNA (22% malignancy prevelance). There was significant difference between the malignancy rates of SRU positive and negative groups (p=0.0192). The sensitivity, specificity, PPV, NPV of thyroid malignancy in our cohort was 91.6%, 33.7%, 27.8% and 93.5% respectively. Conclusion: The application of SRU recommendations reduces the number of benign nodules that undergo workup. Potentially missed malignancies in SRU negative nodules are less aggressive by histologic type and stage compared to SRU-positive malignancies.