title: Complementary roles of 18F-DOPA PET/CT and 18F-FDG PET/CT in medullary thyroid cancer.
abstract: Serum calcitonin and carcinoembryonic antigen (CEA) are markers of recurrent or persistent disease in medullary thyroid cancer (MTC). However, conventional imaging often fails to localize metastatic disease. Our aim was to compare fluorine-labeled dihydroxyphenylalanine ((18)F-DOPA) and (18)F-FDG PET/CT with multidetector CT (MDCT) and MRI in recurrent or persistent MTC.
  
  
  METHODS
  Nineteen MTC patients with increased calcitonin or CEA on follow-up (mean ± SD, 93 ± 91 mo; range, 4-300 mo) after primary therapy were prospectively imaged with 4 techniques: (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI. Images were analyzed for pathologic lesions, which were surgically removed when possible. The correlation between the detection rate for each method and the calcitonin and CEA concentrations and histopathologic findings was investigated.
  
  
  RESULTS
  On the basis of histology and follow-up, one or more imaging methods accurately localized metastatic disease in 12 (63%) of 19 patients. The corresponding figures for (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI were 11 (58%) of 19, 10 (53%) of 19, 9 (47%) of 19, and 10 (59%) of 17, respectively. Calcitonin and CEA correlated with (18)F-DOPA PET/CT (P = 0.0007 and P = 0.0263, respectively) and (18)F-FDG PET/CT findings (both P < 0.0001). In patients with an unstable calcitonin doubling time (n = 8), (18)F-DOPA and (18)F-FDG PET/CT were equally sensitive. In contrast, for patients with an unstable CEA doubling time (n = 4), (18)F-FDG PET/CT was more accurate.
  
  
  CONCLUSIONS
  For most MTC patients with occult disease, (18)F-DOPA PET/CT accurately detects metastases. In patients with an unstable calcitonin level, (18)F-DOPA PET/CT and (18)F-FDG PET/CT are complementary. For patients with an unstable CEA doubling time, (18)F-FDG PET/CT may be more feasible. MRI is sensitive but has the highest rate of false-positive results.
authors: Turku PET Centre, Turku University Hospital, Turku, Finland. saila.kauhanen@utu.fi
authors: Saila
authors: S
authors: Kauhanen
authors: Camilla
authors: C
authors: Schalin-Jäntti
authors: Marko
authors: M
authors: Seppänen
authors: Sami
authors: S
authors: Kajander
authors: Sami
authors: S
authors: Virtanen
authors: Jukka
authors: J
authors: Schildt
authors: Irina
authors: I
authors: Lisinen
authors: Aapo
authors: A
authors: Ahonen
authors: Ilkka
authors: I
authors: Heiskanen
authors: Mika
authors: M
authors: Väisänen
authors: Johanna
authors: J
authors: Arola
authors: Pirkko
authors: P
authors: Korsoff
authors: Tapani
authors: T
authors: Ebeling
authors: Timo
authors: T
authors: Sane
authors: Heikki
authors: H
authors: Minn
authors: Matti J
authors: MJ
authors: Välimäki
authors: Pirjo
authors: P
authors: Nuutila
mesh_terms: D000328:Adult; D000368:Aged; D002116:Calcitonin / Q000378:metabolism; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D018278:Carcinoma, Neuroendocrine; D049109:Cell Proliferation; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012008:Recurrence; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D014057:Tomography, X-Ray Computed
chemical_list: D002272:Carcinoembryonic Antigen; D019394:Ki-67 Antigen; D019788:Fluorodeoxyglucose F18; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; D002116:Calcitonin