Clinical Value of 18-Fluorine-Fluorodihydroxyphenylalanine Positron Emission Tomography/Computed Tomography in the Follow-Up of Medullary Thyroid Carcinoma

Background: 18-fluorine-fluorodihydroxyphenylalanine positron emission tomography (18F-DOPA PET) is a sensitive method for detecting medullary thyroid carcinoma (MTC). The advent of PET/computed tomography (CT) has enabled more sensitive and specific lesion identification using various tracers in many other tumors. The aim of this study was therefore to test the hypothesis that combined 18F-DOPA PET/CT more accurately detects MTC lesions than each modality does alone. Methods: Twenty-eight consecutive 18F-DOPA PET, CT, and 18F-DOPA PET/CT scans of patients followed up for sporadic MTC or multiple endocrine neoplasia 2 syndrome–associated MTC were reviewed retrospectively in randomized sequence by two blinded readers, one a nuclear medicine physician and the other a radiologist, with extensive experience interpreting such images. Results: Of 18 lesions detected concurrently by the three modalities, PET identified all as positive for MTC, but was unable to definitively localize 4 (22%) lesions. CT could def...