Shin-Ichi Miyatake

Fiber-optic spectroscopic detection of neoplasm by intraoperative fluorescence labeling

Abstract Objective: Because the appearances of the neoplasm are frequently similar to the surrounding tissue, it is not necessarily easy to recognize the extent of tumor intra-operatively and to develop the tumor sensor. The purpose of this study is to develop the tumor identification system by application of fluorescence labeling method and spectroscopic analysis. Methods: Light for fluorescence excitation was radiated to the operative field. Fluorescent and reflected excitation lights were conducted to a spectrometer via optical fiber. The spectrum was analyzed in real time every 10 ms. To evaluate the probability of tumor existence, the intensity ratio of fluorescence peak to reflected excitation light was simultaneously calculated. For a preliminary examination, Fluorescein Na and 5 aminorevulinic acid (5-ALA) was administered to two patients with malignant brain tumor. The fluorescent intensity ratio was measured at tumor and brain tissue. Though the brain tissue showed little fluorescence, the spectrum of the tumor part contained fluorescence component. The high contrast ratios of tumor to normal brain fluorescence up to 5.6 in fluorescein Na and 160 in 5-ALA were observed. Conclusions: These results indicated that the neoplasm could be identified using fluorescence labeling method and spectroscopic analysis. The optical fiber type probe is so thin and time resolution is so high that it may be easily integrated with tumor resection apparatus. In conclusion, this system has great potential for tumor identification and resection.

Boron Neutron Capture Therapy of Malignant Gliomas

Boron neutron capture therapy (BNCT) is a promising modality for biochemically targeted, highly selective radiation treatment of various cancers, including malignant gliomas. Currently available results demonstrate the beneficial effect of such therapy on survival of patients with both recurrent and newly diagnosed glioblastomas. The main drawback of BNCT in cases of previously irradiated neoplasms is high rates of symptomatic pseudoprogression and radiation necrosis. For prevention of these complications, concurrent administration of bevacizumab may be helpful. Further studies are needed to establish the optimal therapeutic protocols and to define the exact role of this management option in multimodality treatment strategies. Recent technological developments of accelerator-based neutron sources may simplify placement of the device for BNCT within clinical facilities and lead to wider application of this technique in cases of various cancers.