A new approach of intra-operative real time diagnosis of metastasis by positron probe in gastroenterological carcinomas

点击翻译按钮获取中文摘要

(1)Development of positron probe for intra-operative applicationApollomec corporation developed positron probe with two types of detectors, plastic scintillator for beta rays and BGO crystal for gamma rays. This probe counts as a real event only when both rays are detected simultaneously in order to reduce background level.(2)Committee on clinical application of radioisotopeOur protocol in clinical application is planned to measure radioactivity by positron probe during operation after injection of ^<18>F-FDG in P3 room just before operation. Therefore, the influence to the human body of ^<18>F was evaluated in above-mentioned committee. As a result, the committee approved the usage of ^<18>F, because that half life is very short and the influence to the human body is very little.(3)Examination of injection time of ^<18>F-FDGAs a matter of fact, to delay to start operation is needed to inject ^<18>F-FDG just before operation, because it takes a time to synthesize and purify ^<18>F-FDG. Therefore, we examined whether radioactivity of ^<18>F could be measured or not when ^<18>F-FDG was injected in the evening of the day before operation. The half life of ^<18>F is 109.8 minute. Theoretically, radioactivity is reduced to about 1/256, assuming to measure after 16 hours of injection. We measured radioactivity by gamma probe next morning in patients of esophageal squamous cell carcinoma with huge lymph node metastasis, however, its count was very subtle, so that this protocol of previous day injection was found not to be clinically applicable. Above all, the necessity of injection of ^<18>F-FDG just before operation was suggested to maintain diagnostic quality and accuracy by positron probe.Conclusion : A lot of issues to have to be resolved are still remained, however, FDG-guided surgery may be the promising new approach to have a potential as a breakthrough of quality of surgery.