Imaging Gastric Cancer with PET and the Radiotracers 18F-FLT and 18F-FDG: A Comparative Analysis
Ken Herrmann 1*,
*
Katja Ott 2,
*
Andreas K. Buck 1,
Florian Lordick 3,
Dirk Wilhelm 2,
Michael Souvatzoglou 1,
Karen Becker 4,
Tibor Schuster 5,
Hans-Jürgen Wester 1,
Jörg R. Siewert 2,
Markus Schwaiger 1,
and
Bernd J. Krause 1
1 Department of Nuclear Medicine, Technische Universität München, Munich, Germany
2 Department of Surgery, Technische Universität München, Munich, Germany
3 Department of Internal Medicine III, Technische Universität München, Munich, Germany
4 Department of Pathology, Technische Universität München, Munich, Germany
5 Department of Medical Statistics, Technische Universität München, Munich, Germany
* To whom correspondence should be addressed. E-mail: ken.herrmann{at}web.de.
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Abstract |
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In this pilot study, we evaluated 3'-deoxy-3'-18F-fluorothymidine (FLT) PET for the detection of gastric cancer and compared the diagnostic accuracy with that of 18F-FDG PET. Methods: Forty-five patients (31 male and 14 female) with histologically proven locally advanced gastric cancer underwent attenuation-corrected whole-body 18F-FLT PET and 18F-FDG PET/CT (low-dose CT). 18F-FLT emission images were acquired on a full-ring PET scanner 45 min after the injection of 270–340 MBq of 18F-FLT. 18F-FDG PET/CT was performed 60 min after the injection of 300–370 MBq of 18F-FDG. Mean standardized uptake values for 18F-FLT and 18F-FDG were calculated using circular ROIs (diameter, 1.5 cm) in the primary tumor manifestation site, in a reference segment of the liver, and in the bone marrow and were compared on a lesion-by-lesion basis. Results: According to the Lauren classification, 15 tumors (33%) were of the intestinal subtype and 30 (67%) of the nonintestinal subtype. 18F-FLT PET images showed high contrast for the primary tumor and proliferating bone marrow. In all patients (45/45), focal 18F-FLT uptake could be detected in the primary tumor. In contrast, 14 primary tumors were negative for 18F-FDG uptake, with lesional 18F-FDG uptake lower than or similar to background activity. The mean standardized uptake value for 18F-FLT in malignant primaries was 6.0 ± 2.5 (range, 2.4–12.7). In the subgroup of 18F-FDG–positive patients, the mean value for 18F-FDG was 8.4 ± 4.1 (range, 3.8/19.0), versus 6.8 ± 2.6 for 18F-FLT (Wilcoxon test: P = 0.03). Comparison of mean 18F-FLT and 18F-FDG uptake in tumors with signet ring cells revealed no statistically significant difference between the tracers (6.2 ± 2.1 for 18F-FLT vs. 6.4 ± 2.8 for 18F-FDG; Wilcoxon test: P = 0.94). Conclusion: The results of this study indicate that imaging gastric cancer with the proliferation marker 18F-FLT is feasible. 18F-FLT PET was more sensitive than 18F-FDG PET, especially in tumors frequently presenting without or with low 18F-FDG uptake, and may improve early evaluation of response to neoadjuvant treatment.
Key Words:
FLT, gastric cancer, proliferation, PET
