SOMATOSTATIN RECEPTOR IMAGING IN PERSISTENT MEDULLARY-THYROID CARCINOMA

OBJECTIVE Somatostatin is secreted from thyroid C-cells and seems to p lay an important part in the regulation of calcitonin secretion. We th erefore evaluated the usefulness of somatostatin receptor scintigraphy in the localization of tumour tissue in patients with persistent medu llary thyroid carcinoma. DESIGN A prospective clinical study. PATIENTS The series consisted of 26 patients with elevated calcitonin levels a fter total thyroidectomy for histologically proven medullary thyroid c arcinoma. METHODS Somatostatin receptor scintigraphy using In-111-pent etreotide (Octreoscan) was performed in all patients and the results c orrelated with histology, ultrasonography, computerized tomography, ma gnetic resonance imaging, plain radiography, bone scintigraphy and sel ective venous catheterization. Calcitonin and carcinoembryonic antigen levels were measured. RESULTS The sensitivity of somatostatin recepto r scintigraphy far localization of persistent medullary thyroid carcin oma was 57% in patients with histologically proven disease. The result s depended on tumour mass (low sensitivity (33%) in minimal residual d isease) and on the location of metastases (insensitive in detecting li ver metastases). CONCLUSIONS Somatostatin receptor scintigraphy is of value as an additional diagnostic tool in localizing medullary thyroid carcinoma, especially pulmonary metastases. It is of minor importance in detecting minimal residual disease.