18F-DOPA PET/CT in the diagnosis and localization of persistent medullary thyroid carcinoma
To evaluate the performance of 18F-l-dihydroxyphenylalanine (18F-DOPA) PET/CT in the detection of locoregional and distant medullary thyroid carcinoma (MTC) metastases and to compare imaging findings with histological data.
We retrospectively evaluated 86 MTC patients with persistently high serum calcitonin levels after initial surgery who had undergone 18F-DOPA PET/CT between January 2007 and December 2014 in two referral centres. They were followed up for at least 6 months after the PET/CT assessment. The results were compared with histological data or with the findings obtained during follow-up using a complementary imaging modality.
18F-DOPA PET/CT was positive in 65 of the 86 patients, corresponding to a patient-based sensitivity of 75.6 %. Distant metastatic disease (M1) was seen in 29 patients including 11 with previously unknown metastases revealed only by PET/CT. Among the 36 patients without distant metastatic spread, 25 had nodal involvement limited to the neck, and 10 of these 25 patients underwent reoperation. The lymph node compartment-based sensitivity of 18F-DOPA PET/CT was 100 % in the two institutions but lesion-based sensitivity was only 24 %. Preoperative and postoperative median calcitonin levels were 405 pg/mL (range 128 – 1,960 pg/mL) and 259 pg/mL (range 33 – 1,516 pg/mL), respectively. None of the patients achieved normalization of serum calcitonin after reoperation.
18F-DOPA PET/CT enables early diagnosis of a significant number of patients with distant metastasis. It has a limited sensitivity in the detection of residual disease but provides high performance for regional analysis. A surgical compartment-oriented approach could be the approach of choice whatever the number of nodes revealed by 18F-DOPA PET/CT.
KeywordsMedullary thyroid carcinoma Positron emission tomography 18F-DOPA Neuroendocrine tumours
Compliance with ethical standards
Conflicts of interest
18F-DOPA was used in the setting of marketing authorization. In keeping with local institutional guidelines, all patients gave informed consent for the use of anonymous personal data extracted from their medical records for scientific or epidemiological purposes.
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