Scintigraphic evaluation and dynamic studies with thallium-201 in thyroid lesions with suspected cancer.

Scintigraphic studies of the thyroid with thallium-201 chloride were performed in 46 patients in whom the final diagnosis was established by histology. In dynamic studies of 36 patients, sequential imaging was performed the first 40 min after injection. A single exponential, Cexp(-lambda t), was fitted to each of the curves generated from apparently pathological and from normal regions in each patient, as determined by earlier conventional scintigrams. To minimize the effects of normal individual variations, the relation between pathological (p) and normal (n) regions in the same patient was emphasized and quantified by two parameters, namely the extrapolated zero-time intercept (Cp/Cn) and the time development (lambda p-lambda n) of the ratio of counting rates/unit area in the two regions. The turnover appears to be somewhat slower for pathological tissue than for normal tissue. Although this difference was significant on the 5% level for both cancer and adenoma as a group, only the relative disappearance rate (lambda p-lambda n) resolved cancer frm adenoma and from goiter on the same level. All but one of the differentiated cancers had an increased uptake.