Gamma-camera 18F-FDG PET in diagnosis and staging of patients presenting with suspected lung cancer and comparison with dedicated PET.
It is not clear whether high-quality coincidence gamma-PET (gPET) cameras can provide clinical data comparable with data obtained with dedicated PET (dPET) cameras in the primary diagnostic work-up of patients with suspected lung cancer. This study focuses on 2 main issues: direct comparison between foci resolved with the 2 different PET scanners and the diagnostic accuracy compared with final diagnosis determined by the combined information from all other investigations and clinical follow-up.


METHODS
Eighty-six patients were recruited to this study through a routine diagnostic program. They all had changes on their chest radiographs, suggesting malignant lung tumor. In addition to the standard diagnostic program, each patient had 2 PET scans that were performed on the same day. After administration of 419 MBq (range = 305-547 MBq) (18)F-FDG, patients were scanned in a dedicated PET scanner about 1 h after FDG administration and in a dual-head coincidence gamma-camera about 3 h after tracer injection. Images from the 2 scans were evaluated in a blinded set-up and compared with the final outcome.


RESULTS
Malignant intrathoracic disease was found in 52 patients, and 47 patients had primary lung cancers. dPET detected all patients as having malignancies (sensitivity, 100%; specificity, 50%), whereas gPET missed one patient (sensitivity, 98%; specificity, 56%). For evaluating regional lymph node involvement, sensitivity and specificity rates were 78% and 84% for dPET and 61% and 90% for gPET, respectively. When comparing the 2 PET techniques with clinical tumor stage (TNM), full agreement was obtained in 64% of the patients (Cohen's kappa = 0.56). Comparing categorization of the patients into clinical relevant stages (no malignancy/malignancy suitable for treatment with curative intent/nontreatable malignancy), resulted in full agreement in 81% (Cohen's kappa = 0.71) of patients.


CONCLUSIONS
Comparing results from a recent generation of gPET cameras obtained about 2 h later than those of dPET, there was a fairly good agreement with regard to detecting primary lung tumors but slightly reduced sensitivity in detecting smaller malignant lesions such as lymph nodes. Depending on the population to be investigated, and if dPET is not available, gPET might provide significant diagnostic information in patients in whom lung cancer is suspected.
Department of Clinical Physiology and Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark. peter@oturai.dk
Peter S
PS
Oturai
Jann
J
Mortensen
Henriette
H
Enevoldsen
Annika
A
Eigtved
Vibeke
V
Backer
Knud P
KP
Olesen
Henrik W
HW
Nielsen
Hanne
H
Hansen
Poul
P
Stentoft
Lars
L
Friberg
D019544:Equipment Failure Analysis; D005260:Female; D019788:Fluorodeoxyglucose F18; D015902:Gamma Cameras; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D014055:Tomography, Emission-Computed / Q000295:instrumentation* / Q000379:methods
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18