AIM:
The aim of this study was to evaluate the value of ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PETCT) in restaging of medullary thyroid carcinoma (MTC) patients with rising calcitonin levels.
METHODS:
30 patients (M: F = 11: 19, age 42 + 14 yrs) of treated MTC with high calcitonin levels scheduled for whole body FDG PETCT for restaging. Clinical examination was negative in all pts. 5 pts had suspected lymph nodes on neck ultrasound. Records were analysed with imaging findings. Patients undergoing nodal excision had histological proof as the gold standard in the confirmation of ¹⁸F-FDG PETCT results. Patients were followed up for 12 months to look for persisting disease.
RESULTS:
20/30 (66%) pts had positive FDG PETCT findings. FDG avid sites noted. 2/20 pts had disease in thyroid bed, 8/20 pts had cervical & or mediastinal lymph nodes, 5 pts had distant (lung, liver, skeletal) lesions while remaining 5 patients had both nodal, distant lesions. Histological confirmation was available in 10 pts with locoregional disease on PETCT by surgical excision or FNAC. FDG PETCT imaging yield was higher in patients with higher calcitonin levels ( > 150 pg/ml), sensitivity was calculated as 90%. Mean SUV Max of metastatic nodal disease was 5.12 ± 1.17 and 3.8 ± 1.02, respectively, the difference between the two groups was not statistically significant (P>0.05).
CONCLUSION:
PETCT plays an important role in the evaluation of recurrent MTC , especially in patients with high calcitonin levels. Although the series is small, our study shows that PETCT is instrumental in further decision making.