title: Prospective evaluation of 68Ga-DOTA-NOC PET-CT in patients with recurrent medullary thyroid carcinoma:  comparison with 18F-FDG PET-CT.
abstract: OBJECTIVE
  To prospectively evaluate the role of Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI-octreotide (Ga-DOTA-NOC) PET-CT in patients with recurrent medullary thyroid carcinoma (MTC) and compare the same with F-fluorodeoxyglucose (F-FDG) PET-CT.
  
  
  METHODS
  Fifty-two consecutive patients with recurrent MTC based on raised serum calcitonin levels underwent Ga-DOTA-NOC PET-CT. In addition, 41 patients also underwent F-FDG PET-CT. PET-CT images were evaluated by two experienced nuclear medicine physicians both qualitatively and quantitatively (standardized uptake value). Histopathology (when available), correlation with conventional imaging modalities (ultrasonography/CT/MRI) and subsequent clinical/imaging follow-up were used as reference standard. Serum calcitonin levels were correlated with findings of PET-CT.
  
  
  RESULTS
  Overall, Ga-DOTA-NOC PET-CT showed a sensitivity of 80.7% [95% confidence interval (CI) 67.4-90.3] and a positive predictive value of 100% (95% CI 91.5-100) for detecting recurrent MTC. When both were available (n=41), Ga-DOTA-NOC PET-CT proved superior to F-FDG PET-CT with a higher sensitivity (75.61 vs. 63.4%). However, the difference was statistically not significant (P=0.179). Ga-DOTA-NOC PET-CT was superior to F-FDG PET-CT for detecting recurrence in cervical lymph nodes (P<0.001). Both modalities were concordant in 75% of cases. No significant cut-off level of calcitonin could be derived for either Ga-DOTA-NOC or F-FDG PET-CT.
  
  
  CONCLUSIONS
  Both Ga-DOTA-NOC PET-CT and F-FDG PET-CT are able to localize disease recurrence in patients with MTC, and their role appears to be complementary for this purpose.
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Niraj
authors.initials: N
authors.lastname: Naswa
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.forename: Sudhir
authors.initials: S
authors.lastname: Suman Kc
authors.forename: Sneh
authors.initials: S
authors.lastname: Lata
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Arun
authors.initials: A
authors.lastname: Malhotra
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Bal
mesh_terms: D000328:Adult; D000368:Aged; D018276:Carcinoma, Medullary / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009333:Neck; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
chemical_list: C504894:68Ga-DOTANOC; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18