Prospective Study on the Performance of 18F-DOPA Positron Emission Tomography/Computed Tomography in Patients with Medullary Thyroid Carcinoma

Abstract

Purpose 18F-DOPA Positron Emission Tomography/Computed Tomography (18F-DOPA PET/CT) is a sensitive functional imaging method (65-75%) for detecting disease localization in medullary thyroid cancer (MTC). We aimed: i) to assess the clinical usefulness of 18F-DOPA PET/CT in patients with MTC and elevated calcitonin (Ctn) and CEA levels and, ii) to evaluate changes in disease management secondary to the findings encountered with this methodology. Methods thirty-six patients with MTC and Ctn levels ≥150 pg/ml were prospectively included. Neck ultrasound, chest contrast-enhanced CT, liver magnetic resonance imaging/ abdominal 3-phase contrast-enhanced CT and bone scintigraphy were carried out up to 6 months before the 18F DOPA PET/CT. Results 77.7% were female and 27% had hereditary MTC. Median Ctn level was 1450 pg/ml [150-56620], median CEA level 413 ng/ml [2.9-7436]. Median Ctn DT was 37.5 months [5.7-240]; median CEA DT was 31.8 [4.9-180]. 18F-DOPA PET/CT was positive in 33 patients (91.6%); in 18 (56%) uptake was observed in lymph nodes in the neck or mediastinum, in 7 cases (22%) distant metastases were diagnosed, and in 8 additional patients (24%) both locoregional and distant sites of disease were found. Ctn and CEA levels were higher in patients with ≥ 3 foci of distant metastases. In 14 patients (38.8%), findings on 18F-DOPA PET/CT led to changes in management; surgery for locoregional lymph nodes was the most frequent procedure in 8 patients (22%). Conclusion 18F-DOPA PET/CT was useful for the detection of recurrent disease in MTC and provided helpful information for patient management.