[Detection of thyroid cancer : utopia or reality? Or the value of thallium 201 in thyroid pathology]

Faced with a diagnosis of cold thyroid nodule as evidenced by routine scintigraphy, the clinician has to determine whether this nodule is malignant or not. This is a serious problem since, according to literature, 7-20% of cold thyroid nodules are malignant. In 1982 some Japanese authors demonstrated the possibility of using 201 T1 in diagnosing thyroid tumors. This study refers to 120 patients who underwent an operation for thyroid disorders characterized by the presence of one or several cold nodules (as evaluated with conventional scintigraphy) and enables a comparison between a thorough evaluation of the thyroidal status and the 201 T1 scintigrams. These were obtained with a gamma-camera using a pinhole collimator. If a cold nodule is positive with 201 T1, surgery is incontestably indicated, as such a finding correlates with the existence of a thyroid tumor (benign follicular adenoma or carcinoma) in 89.5% of the observed cases. In the cancer group the sensibility of the Thallium test is of 85% and its specificity 80%. We may assert that there is a very low risk of Thallium negative (old) nodules being malignant. The pre-operative 201 T1 scintigraphy is easy to perform in any Nuclear Medicine department. Nowadays, the combination of aspiration cytology and 201 T1 scintigraphy should make it possible to make and accurate diagnosis in the vast majority of differentiated and undifferentiated thyroid cancers.