In vivo characterization of proliferation for discriminating cancer from pancreatic pseudotumors.
We have determined the ability of PET with the thymidine analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) to detect pancreatic cancer and to differentiate malignant from benign pancreatic lesions.


METHODS
In this prospective study, (18)F-FLT PET was performed on 31 patients with undefined pancreatic lesions. Routine diagnostic procedures included endoscopic ultrasound, MRI, or multislice helical CT of the upper gastrointestinal tract in all patients. Uptake of (18)F-FLT was evaluated semiquantitatively by calculation of mean and maximal standardized uptake values (SUVs). Results were correlated to the reference methods, which were histopathology (23/31) or cytology/clinical follow-up (8/31).


RESULTS
All 10 benign pancreatic lesions were negative on (18)F-FLT PET and showed only background activity (specificity, 100%; 90% confidence interval, 74%-100%). On visual interpretation, 15 of 21 malignant tumors presented as focal (18)F-FLT uptake higher than the surrounding background (sensitivity, 71.4%; 90% confidence interval, 52%-89%). (18)F-FLT PET missed 4 well-differentiated and 2 T1 cancers. Mean (18)F-FLT uptake was 3.1 in all malignant tumors (median, 2.8; range, 1.3-8.5), 3.7 in tumors with visual tracer uptake (median, 3.2; range, 2.1-8.5), and significantly higher in malignant than in benign tumors (mean/median, 1.4; range, 1.2-1.7; P<0.001). For discriminating cancer from benign pancreatic lesions, receiver-operating-characteristic analysis indicated a sensitivity of 81% and specificity of 100% (area under the curve, 0.93) using a mean (18)F-FLT SUV cutoff of 1.8 (maximal (18)F-FLT SUV: area under the curve, 0.92; SUV cutoff, 2.1).


CONCLUSIONS
In this pilot study, focal uptake of the in vivo proliferation marker (18)F-FLT was detected exclusively in malignant tumors. (18)F-FLT PET may therefore be useful as a diagnostic adjunct for differentiating cancer from benign pancreatic lesions.
Herrmann
Ken
K
Department of Nuclear Medicine, Technische Universität München, Munich, Germany.
Eckel
Florian
F
Schmidt
Stefan
S
Scheidhauer
Klemens
K
Krause
Bernd Joachim
BJ
Kleeff
Joerg
J
Schuster
Tibor
T
Wester
Hans-Juergen
HJ
Friess
Helmut
H
Schmid
Roland M
RM
Schwaiger
Markus
M
Buck
Andreas K
AK
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006104:Granuloma, Plasma Cell / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives*
C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D014443:Tyrosine