LIFE provided a sensitivity of 96.4 % and specificity of 49.1 %, suggesting that this technique has limited clinical utility, regardless of the merits of acceptable interobserver bias and lack of necessity for experience with this technique.

Background: Previously, we reported that most gastrointestinal tumors could be distinguished with the Light-Induced Fluorescence Endoscopy for GastroIntestine system (LIFE-GI system) using a fiberscope. However, the quality of the fiberscopic images was inferior compared with videoscopic images. Therefore, we developed a new Auto-Fluorescence Imaging (AFI) videoscope system (manufactured by Olympus Corp.). Methods: We evaluated the clinical usefulness of the AFI videoscope system for the detection of colonic neoplasms. Using this system, we observed 168 colonic polyps. Results: Images obtained by AFI provided better brightness than autofluorescence fiberscopic images and lesion margins were clearly evident. It demonstrated excellent recognition capability to a small lesion that was difficult to be detected by conventional observation. Sensitivity was 89% and specificity 81%, with specificity higher than that of the autofluorescence fiberscopic images. Conclusions: This newly developed AFI videoscope system will be useful for the detection of colonic neoplasms.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. In large GISTs, cystic degeneration, necrosis and focal hemorrhage that occur inside the tumor can result in gastrointestinal bleeding. We describe a case of a 74-year old male with GIST of the stomach accompanied with a giant abscess that penetrated the gastric lumen. The patient experienced undiagnosed fever for two months prior to hospitalization. Gastrointestinal endoscopy, X-ray series and computed tomography of the patient's abdomen revealed a gastric submucosal tumor in the fornix, with a fistula to the gastric lumen that was inundated with a great deal of pus. The mass was diagnosed as a GIST from biopsy specimens. The patient was treated by endoscopic drainage of the abscess and intravenous administration of antibiotics. Eventually, a partial gastrectomy was performed. He was also administered Imanitib mesylate as adjuvant therapy. He was followed up for 2 years and no metastasis or recurrence was recognized at the follow-up examinations. This is the first report of a patient with clearly diagnosed GIST with endoscopic evidence of an abscess penetrating into the gastric lumen.

Autofluorescence spectra of neoplastic tissues have been reported to be significantly different from those of normal tissues when excited by blue or violet light. From this concept, a lightinduced autofluorescence endoscopic imaging system for gastrointestinal mucosa (LIFE-GI; Xillix, Canada and Olympus, Japan) has been newly developed and the clinical evaluation of the prototype system has been conducted in hospitals in Canada, Netherlands and Japan.We examined the clinical usefulness of the prototype LIFE-GI system for the detection of gastrointestinal cancer and high and low grade dysplasia. The LIFE-GI system was also applied to the early detection of remnant lesions after endoscopic treatment of early gastric cancer and to the detection of laterally spreading superficial colonic tumors.This system has potential application for the diagnosis of dysplastic lesions and early cancers in the gastrointestinal tract as an adjunct to ordinary white light endoscopy. This system, which needs no administration of a photosensitive agent, may be suitable as a screening method for the early detection of neoplastic tissues.

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