Integrated nuclear medicine imaging of medullary thyroid cancer

Abstract

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Learning Objectives: 1. Provide an overview of medullary thyroid cancer (MTC) biology and of procedures for staging MTC. 2. Show the benefits of integrated nuclear medicine imaging in the evaluation of neuroendocrine tumors.

Abstract Body: MTC has favorable prognosis if locally confined at diagnosis, but survival decreases dramatically in case of distant metastases. Early recognition of foci of recurrent/metastatic disease allows potentially curative surgery. Nuclear medicine may play an important role when after the initial surgery, tumor recurrence/metastasis is suspected on the basis of elevated tumor markers and the initial radiological evaluation is inconclusive. We present three cases that illustrate the complementary role of somatostatin receptor imaging (SRI), bone scans and PET-FDG in the evaluation of suspected recurrent/metastatic MTC. Because they target different biological characteristics, the combination of these three modalities may yield the best accuracy for detection of residual/metastatic disease. Case 1: 71 yo female with incidental finding of right upper lung nodule found to be MTC. Octreotide scan shows faint uptake in right upper lung. FDG PET/CT found metastasis in a right 7th rib metastasis and a thyroid nodule. Case 2: 64 YOM with history of left MTC with metastases in left cervical lymph nodes presents with elevated calcitonin after surgery. FDG PET/CT shows metastatic cervical lymph nodes. Bone scan shows rib and sternal metastases not appreciated on SRI or PET/CT imaging. Case 3: 51 YOM with history of MTC and elevated calcitonin after surgery. On follow-up, CT reveals liver metastases which are positive on SRI. FDG PET/CT shows hypometabolic liver lesions and no additional sites of disease. The literature on the role and accuracy of nuclear medicine imaging in MTC is reviewed in comparison to other radiologic modalities.