The role of [18F]F-DOPA PET/CT in diagnostic and prognostic assessment of medullary thyroid cancer: a 15-year experience with 109 patients

Objective Correct diagnosis and prognostic evaluation of medullary thyroid cancer (MTC) are crucial to treat patients. The purpose of this study was to evaluate the diagnostic and prognostic value of [ 18 F]F-DOPA PET/CT in patients with MTC. Methods We reviewed MTC patients who underwent [ 18 F]F-DOPA PET/CT from June 2008 to November 2023. Clinical characteristics, follow-up data, and the following [ 18 F]F-DOPA PET/CT parameters were recorded: maximum standardized uptake value (SUV max ), mean standardized uptake value (SUV mean ), metabolic tumor volume (MTV), and SUV mean of multiple organs. The diagnostic value of PET/CT for the detection of tumor lesions was calculated. Serum basal calcitonin (bCt) and stimulated calcitonin (sCt) were determined. Receiver operating characteristics, Kaplan–Meier, and Cox regression analyses were performed. Results In total, 109 patients (50 women, 59 men; average age, 55 ± 14 years) were included in the analysis. The patient-related sensitivity, specificity, and accuracy of [ 18 F]F-DOPA PET/CT were 95%, 93%, and 94%, respectively. The lesion-related sensitivity, specificity, and accuracy were 65%, 99%, and 72%, respectively. The optimal cutoff values of bCt, sCt, and CEA to obtain positive [ 18 F]F-DOPA PET/CT results were 64 pg/mL, 1808 pg/mL, and 4 µg/L, respectively. Patients with negative [ 18 F]F-DOPA PET/CT had longer overall survival than patients with positive [ 18 F]F-DOPA PET/CT results ( P = 0.017). Significant positive correlations were found between bCt, sCt, and CEA with SUV max , SUV mean , and MTV of [ 18 F]F-DOPA PET/CT ( P < 0.001). [ 18 F]F-DOPA PET/CT results and MTV may be useful for the evaluation of the prognosis of patients with recurrent MTC, while age and MTV were independent prognostic factors in patients with primary MTC. For all patients, SUV mean of the left kidney, liver, aorta, and pancreas might be used to independently predict OS. Conclusion [ 18 F]F-DOPA PET/CT had great value for diagnosis and prognostic assessment in patients with MTC. The DOPA PET/CT parameter SUV mean and MTV showed significant association with OS.