title: Comparison of 18F-FDG and 67Ga-citrate in sarcoidosis imaging.
abstract: OBJECTIVE
  (67)Ga citrate has been used long and successfully to diagnose and stage sarcoidosis. (18)F-fluorodeoxyglucose ((18)F-FDG) has been suggested as a positron emission tomography (PET) tracer for sarcoidosis imaging. This study aimed to analyze possible advantages of (18)F-FDG-PET over (67)Ga citrate scintigraphy during the primary assessment of patients with sarcoidosis.
  
  
  METHODS
  Twenty-four patients (11 men, 13 women, aged 52 years +/-12.4) with histologically proven sarcoidosis were investigated with (18)F-FDG and (67)Ga citrate. Equipment included a full-ring PET scanner (ECAT EXACT HR+, Siemens/CTI, Knoxville TN, USA) and a double-headed gamma camera (ECAM, Siemens, Illinois, USA) for scintigraphy. The mean time difference between the two studies was 6.5 days (range: 5-8 days).
  
  
  RESULTS
  There was a significant difference in the detection of pulmonary and nonpulmonary sarcoidosis lesions between planar (67)Ga citrate scans and (18)F-FDG-PET images (<0.0021). A total of 64 lesions were detected with (67)Ga citrate scans in the thorax and elsewhere with a mean of 2.6 lesions (4%) per patient, while 85 lesions were found with (18)F-FDG-PET, with a mean of 3.5 lesions (4.1%) per patient. There was complete agreement between (18)F-FDG and (67)Ga citrate in thoracic manifestations in four (16.6%) patients, and in non-thoracic manifestations in five (20.8%) patients. The interobserver variability showed a kappa value of 0.79.
  
  
  CONCLUSIONS
  (67)Ga citrate and (18)F-FDG are useful tracers for diagnostic evaluation of thoracic sarcoidosis. (18)F-FDG seems to be more suitable for imaging the mediastinum, the bi-hilar lymph nodes, the posterior regions of the lungs and non-thoracic lesions. Further prospective studies are needed to clarify the role of both tracers in early diagnosis and staging of sarcoidosis, and to resolve questions concerning medical treatment and follow-up.
authors.affiliation: Division of Nuclear Medicine, Medical University of Graz, Auenbruggerplatz 9, 8036 Graz, Austria. eva.prager@gmx.net
authors.forename: E
authors.initials: E
authors.lastname: Prager
authors.forename: M
authors.initials: M
authors.lastname: Wehrschuetz
authors.forename: B
authors.initials: B
authors.lastname: Bisail
authors.forename: M
authors.initials: M
authors.lastname: Woltsche
authors.forename: T
authors.initials: T
authors.lastname: Schwarz
authors.forename: H
authors.initials: H
authors.lastname: Lanz
authors.forename: E
authors.initials: E
authors.lastname: Sorantin
authors.forename: R M
authors.initials: RM
authors.lastname: Aigner
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D002951:Citrates; D005260:Female; D019788:Fluorodeoxyglucose F18; D005708:Gallium; D005710:Gallium Radioisotopes; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012507:Sarcoidosis / Q000097:blood / Q000000981:diagnostic imaging*; D014916:Whole-Body Irradiation
chemical_list: D001786:Blood Glucose; D002951:Citrates; D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005708:Gallium; C103850:gallium citrate