An assessment of the potential role of routine radionuclide thyroid scanning in the differentiation between solid and cystic lesions in the solitary thyroid nodule.

The value of the conventional 99mTc-pertechnetate scan, to differentiate cystic from solid solitary or dominant non-functioning nodules in the thyroid was investigated in 104 patients. Although these nodules are thought to be non-functioning, a low level of radioactivity can be detected in some of the nodules. The assessment was based on the level of radioactivity in the nodules. The nodules with higher activity were considered to have a higher probability of being solid. This diagnosis was confirmed either by ultrasound, or by histological examination, or both, and sensitivity and specificity evaluated with ROC curve analysis which reached 81% sensitivity with a specificity of 44%. The method was more reliable for larger than for smaller nodules reaching a sensitivity of 81% with a specificity of 84%. The results indicate that 99mTc-pertechnetate scanning can provide a useful procedure to distinguish between cystic and solid lesions in the thyroid.