title: Detection of occult medullary thyroid cancer recurrence with 2-deoxy-2-[F-18]fluoro-D-glucose-PET and PET/CT.
abstract: OBJECTIVE
  2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) has an established role in restaging of various cancers, including papillary and undifferentiated thyroid carcinoma. However, controversies exist regarding its ability to reliably assess recurrent medullary thyroid cancer (MTC). We were therefore prompted to review our experience with FDG-PET for detection of occult MTC.
  
  
  METHODS
  This is a retrospective study (Apr 1, 1997-Mar 31, 2004) of 13 patients with histologic diagnosis of MTC, who had PET examinations. The group included six men and seven women, 15-62 years old (average: 48+/-13). The PET scan request was triggered by rising levels of calcitonin and negative anatomical imaging studies.
  
  
  RESULTS
  Recurrent/metastatic disease was identified by PET in seven (54%) of the 13 patients. The lesions were located in superior mediastinum (4), cervical lymph nodes (3), thyroid bed (2), lung (1) and liver (1). The calcitonin levels ranged from 52 to 5,090 pg/ml (average: 1,996 pg/ml) in patients with negative PET scans and from 132 to 9,500 pg/ml (average: 3,757 pg/ml) in patients with positive studies. The sensitivity and specificity of FDG-PET for disease detection in this cohort were 85.7% (95% CI: 48.7-97.4) and 83.3% (95% CI: 43.6-96.9), respectively.
  
  
  CONCLUSIONS
  Our findings suggest a significant role for FDG-PET in patients with suspected MTC recurrence, with sensitivity of 85.7% and specificity of 83.3% for disease detection. FDG-PET provides additional information in a significant fraction of cases (54%) and could be used for restaging of patients with MTC and elevated levels of biomarkers (calcitonin). Additional studies are necessary to further evaluate the role of FDG-PET in MTC.
authors.affiliation: PET Imaging Science Center, Department of Radiology, University of Southern California, Keck School of Medicine of USC, 1510 San Pablo St, Suite 350, Los Angeles, CA 90033, USA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Iagaru
authors.forename: Rinat
authors.initials: R
authors.lastname: Masamed
authors.forename: Peter A
authors.initials: PA
authors.lastname: Singer
authors.forename: Peter S
authors.initials: PS
authors.lastname: Conti
mesh_terms: D000293:Adolescent; D000328:Adult; D020295:Brain Stem Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18