Division of Science and Technology for Endoscopy

[Kashiwa Campus] Hiroaki Ikematsu, Tomonori Yano, Keisuke Hori, Takako Mamada

[Tsukiji Campus]Yutaka Saito, Seiichiro Abe, Masayoshi Yamada, Satoru Nonaka, Taku Sakamoto, Yudai Izumo, Megumi Kanno, Noriko Torii

Introduction

Now, endoscopy is widely used for screening, diagnosis, and treatment for early cancer in aero-digestive tracts including the pharynx, esophagus, stomach, and colorectum. With conventional endoscopy, observations are made using white light to illuminate the mucosal surface with special attention paid to the appearance of reddish and irregular portions compared to adjacent areas. Thus, the detection of suspicious early cancerous lesions has been largely based on the macroscopic characteristics of lesions. Still, the detection is difficult for all endoscopists.

One of the characteristics of early cancer is the growth of blood vessels (neovascularity). It is reported that image-enhanced endoscopy (IEE), such as narrow band imaging (NBI) and blue laser imaging (BLI), is efficacious to detect superficial squamous cell carcinoma in the head and neck region and esophagus. However, the efficacy is controversial in the stomach and colorectal region.

Another characteristic of a tumor is hypoxia. As a tumor grows, it rapidly outgrows its blood supply, leaving portions of the tumor with regions where the oxygen concentration is significantly lower than in healthy tissues. Thus, there have been attempts to visualize spatial distribution of tumor hypoxia, such as fluorescent labeling techniques or hemoglobin absorption-based techniques. However, these methods are limited because of low spatiotemporal resolution. We developed an imaging technology that can derive oxygen saturation (StO2) images from small numbers of wavelength measurements.

The next-generation novel endoscopy will be required to make visible specific functions in cancerous tissues.

Research activities

Present research activities mainly focus on the development of new instruments for endoscopic diagnosis and new endoscopic treatment modalities. Developing research on novel endoscopy systems and devices is being performed. Hypoxia imaging is detected for neoplastic lesions of the head and neck and alimentary tracts, with two types of visualized images: a pseudocolor StO2 image and a StO2 overlay image. Another project is a new bioimaging system using near-infrared light with a wavelength of over 1,000 nm with various spectrums. This system is capable of penetrating through the gastrointestinal wall and obtaining images. A novel diagnosis system using photosensitizing agents, such as hypericin, has been constructed. Also, A novel tattooing system under endoscopy has been developed. Now, a patent is being sought for this system. Ongoing projects are to develop needle graspers, needle ultrasonic coagulators in the surgical field.

Clinical trials

1)POC study of SO2 imaging endoscopy (UMIN 000008402)

2)Phase II study of biodegradable stents (BD-stent) for refractory benign esophageal strictures after curative treatment of esophageal cancer (UMIN000008054)

3)Development of diagnostic endoscopy for GIST using near infrared light

Education

Meetings are constantly conducted with faculties including technology and science students of the university.

Future prospects

Existing endoscopic diagnosis for neoplasia of the alimentary tract is performed on the basis of the morphological features of tumors. Molecular imaging endoscopy is a novel system to visualize cancer using a specific laser source under phosphor combined with cancer-specific agents. We can obtain new imaging, since functions or the metabolic state in cancer cells is visualized. In additional modalities, there are photodynamic diagnosis, endomicroscopy, and hypoxia imaging endoscopy. We endeavor to perform first-in-human clinical trials. These modalities will be expected as next-generation endoscopy, and we try innovative approaches to produce all-new endoscopy in collaboration with academia and companies. The foregoing approach will be started also at the Tsukiji campus in the next fiscal year.