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68. Functional diagnosis and evaluation of therapeutic effects of cancer using PET
Kyosan Yoshikawa, Katsumi Tamura, Yasunori Imai, Noriyo Matsuno, Masahisa Koga, Masakuni Kanai, Susumu Kandatsu, Hirohiko Tsujii, Tetsuya Suhara, Katsuya Yoshida,Kazutoshi Suzuki, Osamu Inoue1, Fumio Shishido2, and Hiroshi Fukuda3
(1Ohsaka Univ.; 2Fukushima Medical Univ.; 3Tohoku Univ.)
Keywords: Positron Emission Tomography, C-11 methionine, Cancer
The role of PET in clinical diagnosis of cancer and the evaluation of therapeutic effects were studied. Positron emission tomography can demonstrate increased metabolic demand as visual images, and produces alternative information for diagnosis which can be used to complement morphological observations. The recent advance of PET scanner has enabled us to perform whole body PET scan. We studied if PET could be succesfully used for the detection and the evaluation of lung cancer. The lung tumor was detectable by whole body PET in 22 of 24 patients (91.7%). Six of seven (85.7 %) small lung tumors under 2.0 cm in diameter were detected and the minimal size of detectable tumor was 1.3 cm. The visual scale had a tendency to move according to the changes of SUV and size of the tumor. Tumor size of two (-) cases were 1.2 cm and 2.1 cm and SUVs of those were 0.98 and 1.04 respectively. We conclueded that F-18 FDG PET was useful for the detection of small peripheral type lung cancers.
The change of C-11 methionine uptake in tumor between pretreatment and post-treatment using HIMAC was compared with clinical prognosis. PET findings at pretreatment and post-treatment were compared with results of clinical observation of patients. We think that the level of accumulation in the tumor at pretreatment might correlate to the risk of metastasis and the reduction rate might correlate to local control level. If methionine does not accumulate at high levels in the tumor at pretreatment, methionine PET might not be a good indicator of patient prognosis, and we should use other indexes to evaluate patients prognosis after treatment in such cases.
