RADIOLABELED SOMATOSTATIN ANALOG SCINTIGRAPHY IN DIFFERENTIATED THYROID-CARCINOMA

After intravenous administration of a radiolabeled somatostatin analog (octreotide), an image of the thyroid gland is frequently observed; f ew data are available, however, on somatostatin receptors in epithelia l thyroid cells assessed in vitro and on images of differentiated thyr oid carcinoma (DTC) with pentetreotide scintigraphy. Methods: In four patients with metastatic thyroid carcinoma, whole-body scintigraphy wa s performed 4 to 48 hr after injection of 110 MBq of In-111-pentetreot ide. The results were compared to data obtained with other imaging mod alities, including scintigraphy performed after administration of a th erapeutic dose of I-131. Results: There were positive foci in distant metastases on In-111-pentetreotide scintigraphy. Pentetreotide scintig raphy was positive in two patients with an ''insular'' form of DTC, on e of whom had a positive (faintly) I-131 scan. Of the other two patien ts with papillary DTC without radioiodine uptake, only one exhibited a certain degree of pentetreotide scintigraphy positivity in distant me tastases. Conclusion: These results show promise for exploration of in sular thyroid carcinoma and suggest that these carcinomas may possess functional differentiation features, including somatostatin receptors.