Background: The high prevalence of thyroid nodules in iodine-deficient areas is a practical problem because of the large number of patients requiring fine needle aspiration (FNA) to detect malignant nodules.
Aim: To obtain an ultrasound (US) score for predicting malignant nodules and reduce the number of unnecessary and expensive FNA.
Subject and method: All nodules observed from September 2001 to March 2006 were evaluated by US: echostructure, echogenicity, halo, microcalcifications and ratio between antero-posterior and transversal diameters (AP/TR). Two thousand six hundred and forty-two consecutive patients underwent US-guided FNA for a total of 3645 nodules.
Results: Logistic regression analysis showed a potent predictive role for solitary nodules and absence/ incomplete halo (p=0.000). A significant predictive role for microcalcifications and AP/TR ratio was also observed. A 10-point score was constructed using the standardized regression coefficient. Nodules with US score <or=2.4, those between 2.5-5.4 and >or=5.5 had a frequency of malignancy of 0.4, 1.1 and 5.6% (p<0.001), respectively. Nodules with >or=5.5 US score were characterized by a 66% sensitivity and a 76% specificity compared to the diagnostic values of single parameters which were either sensitive or specific.
Conclusions: According to our data, we suggest FNA for nodules reaching a >5.4 US score, whereas a clinical judgement should be used for the intermediate category nodules. When the score is lower than 2.5 we do not recommend FNA. The practical use of this US score can help reduce unnecessary and expensive FNA in iodine-deficient areas.