PET with O-(2-18F-Fluoroethyl)-L-Tyrosine in peripheral tumors: first clinical results.
O-(2-18F-Fluoroethyl)-L-Tyrosine (18F-FET) PET has shown promising results in brain tumor diagnosis. The aim of this prospective study was to evaluate 18F-FET PET in comparison with 18F-FDG PET in patients with peripheral tumors.


METHODS
Forty-four consecutive patients with suspected malignant tumors underwent 18F-FET PET and 18F-FDG PET within 7 d. Whole-body PET studies were performed 1 h after intravenous injection of 370 MBq of 18F-FET or 18F-FDG. Six patients were excluded from the analysis because a malignant tumor could not be verified. In 38 patients (7 with colorectal cancer, 6 with pancreatic cancer, 9 with head-neck cancer, 4 with lymphomas, 3 with lung cancer, 3 with ovarian cancer, 4 with breast cancer, and 2 with prostatic cancer), 18F-FET PET and 18F-FDG PET were compared.


RESULTS
18F-FET was positive in only 13 of 38 patients (8 with head-neck cancer, 3 with breast cancer, and 2 with lung cancer), whereas 18F-FDG exhibited increased uptake in 37 of 38 patients. All squamous cell carcinomas were found to be 18F-FET-positive tumors (8 head-neck cancer and 2 lung cancer), whereas most adenocarcinomas were found to be 18F-FET-negative tumors. In patients with colorectal cancer, pancreatic cancer, ovarian cancer, prostatic cancer, and lymphomas, no increased 18F-FET uptake could be identified. All lesions that exhibited increased 18F-FET uptake also showed increased 18F-FDG uptake. No additional lesion was identified by 18F-FET PET but not by 18F-FDG PET. A subgroup analysis of patients with head-neck carcinomas allowed a better distinction between malignant and inflammatory tissues with 18F-FET than with 18F-FDG.


CONCLUSIONS
18F-FET is inferior to 18F-FDG as a PET tracer for general tumor diagnosis. Our preliminary results suggest rather selective uptake of 18F-FET in squamous cell carcinomas. Compared with 18F-FDG PET, 18F-FET PET may allow a better distinction between tumors and inflammatory tissues in patients with squamous cell carcinomas.
Pauleit
Dirk
D
Clinic of Nuclear Medicine, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany. pauleit@web.de
Stoffels
Gabriele
G
Schaden
Winfried
W
Hamacher
Kurt
K
Bauer
Dagmar
D
Tellmann
Lutz
L
Herzog
Hans
H
Bröer
Stefan
S
Coenen
Heinz H
HH
Langen
Karl-Josef
KJ
D000328:Adult; D000368:Aged; D005240:Feasibility Studies; D005260:Female; D005462:Fluorine Radioisotopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging*; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives*
D005462:Fluorine Radioisotopes; C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D014443:Tyrosine