Somatostatin receptor imaging in persistent medullary thyroid carcinoma

OBJECTIVE Somatostatin is secreted from thyroid C-cells and seems to play an Important part In the regulation of calcitonin secretion. We therefore evaluated the usefulness of somatostatin receptor scintigraphy in the localization of tumour tissue in patients with persistent medullary thyroid carcinoma. DESIGN A prospective clinical study. PATIENTS The series consisted Of 26 patients with elevated calcitonin levels after total thyroldectomy for histologically proven medullary thyroid carcinoma. METHODS Somatostatin receptor scintigraphy using ¹¹¹ In-pentetreotide (Octreoscan) was performed in all patients and the results correlated with histology, ultrasonography, computerized tomography, magnetic resonance Imaging, plain radiography, bone scintigraphy and selective venous Catheterization. calcitonin and carcinoembryonic antigen levels were measured. RESULTS The sensitivity of somatostatin receptor scintigraphy for localization of persistent medullary thyroid carcinoma was 57% in patients with histologically proven disease. The results depended on tumour mass (low sensitivity (33%) in minimal residual disease) and on the location of metastases (Insensitive in detecting liver 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.