Dual PET/CT with (18)F-DOPA and (18)F-FDG in metastatic medullary thyroid carcinoma and rapidly increasing calcitonin levels: Comparison with conventional imaging.
BACKGROUND
To evaluate the role of a multi-imaging PET with (18)F-DOPA and (18)F-FDG in comparison with conventional imaging (CI) in recurrent medullary thyroid carcinoma (MTC).


METHODS
18 MTC patients who had thyroidectomy were included; they presented with elevated and rapidly increasing calcitonin levels during follow up. CI had revealed metastatic deposits in 9 patients. Patients were referred to us for a PET/CT with (18)F-DOPA and (18)F-FDG. Histologic/cytologic confirmation of recurrent MTC was obtained in at least one PET-positive lesion in all patients.


RESULTS
Foci of abnormal uptake were observed in 15 patients at (18)F-DOPA and in 11 at (18)F-FDG; 8 patients showed the same number of positive lesions with both tracers, 2 showed more lesions on (18)F-FDG, 1 was positive at (18)F-FDG alone and 5 at (18)F-DOPA alone. In 3 patients with a DOPA-positive loco-regional relapse a re-operation with curative intent was offered. SUV(max) values were higher for (18)F-FDG compared to (18)F-DOPA (mean 12.7+/-4.1 vs. 5.5+/-2.1, p<0.05). Calcitonin was higher in PET-positive patients compared to PET negative ones, while no significant differences were observed between (18)F-DOPA and (18)F-FDG positive patients.


CONCLUSIONS
In MTC patients with rapidly increasing calcitonin levels during follow up, (18)F-DOPA has a good sensitivity and a complementary role with (18)F-FDG PET/CT in detecting metastatic deposits. In our experience, the sensitivity of a multi-imaging (18)F-DOPA &(18)F-FDG PET/CT approach is greater than that obtained with CI. The higher SUV(max) values found with (18)F-FDG in some patients may reflect more aggressive tumors.
Marzola
M C
MC
Department of Nuclear Medicine, Medical Physics, Radiology, Santa Maria della Misericordia Hospital, Viale Tre Martiri 140, 45100, Rovigo, Italy.
Pelizzo
M R
MR
Ferdeghini
M
M
Toniato
A
A
Massaro
A
A
Ambrosini
V
V
Fanti
S
S
Gross
M D
MD
Al-Nahhas
A
A
Rubello
D
D
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D002116:Calcitonin / Q000097:blood; D018276:Carcinoma, Medullary / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D016009:Chi-Square Distribution; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D011859:Radiography; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D013965:Thyroidectomy
D014408:Biomarkers, Tumor; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; D002116:Calcitonin