Gallium-68 dotatate PET/CT is superior to other imaging modalities in the detection of XXXX of the thyroid in the presence of high serum calcitonin.

@entity5 @entity11166 @entity1 @entity189
OBJECTIVE: @entity189 of the thyroid ( @entity11166 ) is a rare @entity5 ( @entity5 ) that expresses somatostatin receptors on the cell membrane and secretes calcitonin. Surgery is the primary curative modality but is achieved only when the diagnosis is timely so there is a high rate of persistent and recurrent disease indicated by a rise in the serum calcitonin levels. Successful management of recurrent disease requires accurate localisation with cross sectional and functional imaging. The introduction of gallium-68-Dotatate ((68)Ga-Dotatate) peptides positron emission tomography/computerized tomography (PET/CT) has significantly improved the detection of @entity5 and has been reported as a valuable adjunct in @entity11166 localisation. We retrospectively reviewed our cases of @entity11166 to correlate the detectability of (68)Ga-Dotatate in relation to calcitonin levels and assess suitability of inoperable @entity1 for peptide receptor radionuclide therapy (PRRT). SUBJECTS AND METHODS: Seven @entity1 (age range 31-66 years, M:F 3:4) with raised calcitonin (mean=7,143pg/mL) were referred for (68)Ga-Dotatate PET/CT scan for localisation of persisting recurrent @entity11166 . Six @entity1 were known to have @entity11166 treated with thyroidectomy and one @entity1 was presenting for the first time. All @entity1 had multiple imaging including ultrasound (US), CT, magnetic resonance imaging (MRI), fluorine-18-fluorodeoxyglucose ((18)F-FDG) PET/CT and iodine-123-metaiodobenzylguanidine ((123)I-MIBG). Positive findings were defined as areas of increased uptake other than the organs of normal distribution and were correlated with results of biopsies, other imaging, long term monitoring of calcitonin and clinical follow up. RESULTS: In 6/7 @entity1 with very high serum calcitonin (range= 672-37,180, mean=8,320pg/mL) (68)Ga-Dotatate PET/CT confirmed the presence of active disease seen on other modalities or detected hitherto unsuspected lesions. In at least 3 cases, (68)Ga-Dotatate PET/CT showed many more lesions compared to other imaging combined. In 1/7 @entity1 (68)Ga-Dotatate PET/CT was negative in line with a relatively low calcitonin level (80pg/mL) and negative disease on fine needle aspiration. CONCLUSION: (68)Ga-Dotatate PET/CT is an effective tool for localising metastatic spread of @entity11166 . It appears to be most effective in the presence of higher levels of serum calcitonin, probably in excess of 500pg/mL. The results of our small cohort had an impact on staging and management with the introduction of peptide receptor radionuclide therapy for inoperable disease.
