Ultrasound and radionuclide imaging in management of thyroid nodules

Radionuclide thyroid scanning using either 99Tcsup(m) or 131I and ultrasound imaging with a 5.0 MHz transducer and B-mode scanner were performed on 174 patients. Of these patients, 71% were found to have solitary 'cold' nodules on a radionuclide scan, of which 44% were subjected to surgery. Echo patterns of the nodules were classified into echo free and echogenic groups. Comparison of histopathology with echo characterization showed that 92% of the cystic nodules and nodules having cystic changes showed echo free patterns, while 90% of the histopathologically solid nodules were echogenic, thereby confirming the structural correlation. Amongst the patients subjected to surgery, the incidence of malignancy in cold nodules seen by radionuclide scanning alone was 26%, while it was 22% in echogenic nodules seen by ultrasound imaging alone. In patients having echogenic, cold nodules the incidence of malignancy increased to 37%. Ultrasound imaging of the thyroid was found useful in patients where radionuclide scanning either was not decisive or could not be performed. (author)