Comparison of 18F-FDG and 67Ga-citrate in sarcoidosis imaging.
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.
Prager
E
E
Division of Nuclear Medicine, Medical University of Graz, Auenbruggerplatz 9, 8036 Graz, Austria. eva.prager@gmx.net
Wehrschuetz
M
M
Bisail
B
B
Woltsche
M
M
Schwarz
T
T
Lanz
H
H
Sorantin
E
E
Aigner
R M
RM
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
D001786:Blood Glucose; D002951:Citrates; D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005708:Gallium; C103850:gallium citrate