Assessment of medullary thyroid carcinoma with F-18 DOPA PET/CT in comparison to F-18 FDG PET/CT

摘要

Objectives: Many imaging modalities were suggested for diagnosis and follow up of patients with medullary thyroid carcinoma (MTC) and elevated calcitonin levels. F-18 DOPA PET and F-18 FDG PET were introduced as the most accurate functional methods for evaluation of patients with MTC. The aim of this study was to evaluate the potential role of F-18 DOPA PET/CT for assessment of MTC in comparison to F-18 FDG PET/CT. Methods: 16 patients (10 women & 6 men) with MTC underwent both imaging modalities within 8 weeks without any therapy management between these two investigations. All patients had an elevated calcitonin level (mean 2327 + 3408 pg/ml, median 884) and CEA (mean 82 + 167 ng/ml) with a pathologic pentagastrine test. 5 patients were assessed preoperatively and 11 patients in follow-up. The imaging’s data were assessed by two independent experts. All detected lesions - classified as local recurrence, lymph node, bone and organ metastases - were verified by histological results or follow-up studies. Results: Overall 28 lesions were detected by F-18 DOPA PET/CT but only 14 lesions were detected by F-18 FDG PET/CT. 10 local recurrences, 5 lymph nodes, 10 bone lesions and 3 liver metastases were determined by F-18 DOPA PET/CT, whereas 5 local lesions, 1 lymph node, 6 bone lesions and 2 liver metastases were detected using F-18 FDG PET/CT. One inflammatory lesion (false positive) was detected in the lung by F-18 FDG PET/CT. F-18 DOPA PET/CT was clearly superior in the detection of local recurrence and lymph node metastases; furthermore all pathologic lesions were determined earlier. Higher tracer intensity was visualized in foci detected by F-18 DOPA PET/CT in comparison to F-18 FDG PET/CT by means of SUVmax. Five patients had a negative scan in both imaging modalities in spite of elevated calcitonin and CEA level and pathologic pentagastrine test. Conclusion: F-18 DOPA PET/CT provides more sensitive and superior results than F-18 FDG PET/CT in preoperative determination and staging as well as in the early detection of recurrence and distant metastases of MTC patients.