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Laser application in gastrointestinal endoscopy started with the development of flexible optical fibers in about 1970. Originally, non-contact irradiation with high power Nd: YAG lasers of 100 watts (W) was used for gastrointestinal hemostasis. It was difficult to achieve safe and reliable irradiation with this method, the quarts fiber tips were susceptible to coagulation damage, and the cost was high. As a result local injections were recognized as an inexpensive and excellent method of producing hemostasis, and became the treatment of first choice. Therefore, the endoscopic use of lasers shifted from hemostasis to the topical treatment of tumors. In 1984 low-power Nd: YAG laser irradiation at 1 to 30W became possible using a ceramic contact probe co-developed by the authors and the Surgical Laser Technology Japan Co. This made photocoagulation, vaporization, cutting and local hyperthermia (Laserthermia) feasible. Improvements in laser irradiation efficiency led to the development of inexpensive equipment, costing less than one-third of the price of conventional equipment. The application of low-power contact lasers significantly improved the clinical efficacy of the treatment of minute cancers, but the technique has the same limitations as other endoscopic methods. Furthermore, because laserthermia is still being developed, the best technique has not yet been fully defined. In the future, treatments that can be used effectively in association with low-power contact laser therapy need to be identified. Low-power contact laserthermia, local hyperthermia with microwaves, and photodynamic therapy with excimer dye lasers all need to be studied further. This will contribute to the development of a minimum invasive therapy for gastrointestinal lesions.

With the increasing demand on picture archiving and communication systems (PACS) to handle larger numbers of images, much research has been conducted on the utilization of lossy compression for efficient communication and storage in PACS systems. The receiver operating characteristics (ROC) method is commonly used to determine the appropriate compression ratio of lossy images. However, conducting an ROC experiment is impractical at actual medical facilities because it is difficult to prepare and interpret images with different compression ratios for each modality, body part, and acquisition method. On the other hand, experienced radiologists have the ability to subjectively assess the level of image quality required for interpretatior and quantitative analysis. Therefore, by simply viewing images, they are able to determine the appropriate criteria for image quality and derive a practical compression ratio for each application. The present study focused on lossy compression as employed in teleradiology systems for medical checkups. Experiments comparing radiologists' subjective assessment of compressed images against the diagnostic results obtained using these images were conducted in order to investigate appropriate compression ratios and efficient methods for determining them.

A 52 year-old female was admitted to our hospital for lung cancer. We performed upper gastrointestinal endoscopy for her complaint of epigastralgia, and diagnosed Borrmann 2 type gastric cancer on the posterior wall of the angle. Chemotherapy with CDDP and VDS was commenced for lung cancer, and endoscopic Nd- YAG laser local hyperthermia (Laserthermia) was carried out for gastric cancer. Nd- YAG laser provided computer-controlled thermo-monitering system was irradiated in 3W, intermittently. Laserthermia could be applied safely to the clinical endoscopy. Conclusions were as follows; 1) Borrmann 2 type gastric cancer complicated with lung cancer was treated with laserthermia without severe complication. 2) This is the first report that the Laserthermia controlled by computer thermo-system was put in to clinical use. 3) Laserthermia with chemotherapy was more effective than laserthermia alone.

Six solitary gastric polyps in the acid-secreting fundic mucosa were histochemically investigated using the mucin histochemistry, immunoperoxidase method, and silver methods for endocrine cells. Histologically, the polyps were grouped into three types: they largely consisted of either hyperplastic foveolar cells (group 1), normal-appearing fundic gland cells with mild cystic changes (group 2) or hyperplastic fundic gland cells with cystic dilatation (group 3). The presence of parietal cells and mucous neck cells was confirmed in all polyps by the immunoperoxidase method using parietal cell autoantibody and the paradoxical Concanavalin A staining, respectively. Regarding the endocrine component, somatostatin-containing cells, Grimelius-positive argyrophil cells, and Fontana-Masson-positive enterochromaffin cells were scattered in the fundic gland area of the polyps as well as in the surrounding normal-appearing fundic mucosa. Gastrin-containing cells were absent. In one of the group 2 polyps and both group 3 polyps, a varying number of glicentin-containing cells were found among the fundic gland components: In one polyp in group 3, glucagon immunoreactivity was detected in the glicentin-containing cells. These findings suggest that some of the polyps express characteristics of the fetal fundic mucosa, since glicentin and glucagon immunoreactivities in normal human stomach have been detected exclusively in the fetal fundus.

We have been studying experimentally and clinically to evaluate the histological effects and safety of the therapeutic Nd-YAG laser endoscopy by the contact method with new ceramic endoprobes comparing wit Li those by the non-contact method with single quartz fiber. In this paper, we would like to discuss possibilities of clinical application of endoscopic local hyperthermia using Nd-YAG laser (Laserthermia) with computer control system. Newly developed computer controlled Laserthermia may possible to apply for the treatment of the malignant tumor in the gastrointestinal (GI) tract.

Since 19843 we have been studying endoscopic laser induced hyperthermia (laserthermia) with SLT frosted contact probe and low power Nd-YAG laser irradiation under 5 watts" The endoscopic laserthermia have been reported endoscopically such as tumor reduction3. In this paper, we would like to discuss the comparative histological studies between the first prototype laserthermia system. with Medilas(M..B.B.) Nd-YAG laser and the new laser-thermia system with SLT Contact Laser on canine stomach, and report clinical application of endoscopic laserthermia to the gastric cancers. The computer controlled laserthermia will be possible to apply for the treatment of the malignant tumor in the gastrointestinal (GI) tract.

Endoscopy of the upper gastrointestinal tract was performed on 84 patients with end-stage chronic renal failure undergoing hemodialysis. Gastric acid secretion and fasting plasma gastrin levels were also examined in these patients. Hemorrhagic gastritis was most frequently observed (23 cases) followed by erosive gastritis (18 cases). No patients had gastric ulcers. Duodenal ulcers were observed in only two patients. Gastrointestinal bleeding was observed in 15 cases (17.9%). Thirteen of these 15 cases had hemorrhagic gastritis, one of which had a duodenal ulcer as a complication. Fasting plasma gastrin levels (359.6 +/- 336.5 pg/ml) were significantly higher than those of normal subjects (35.2 +/- 37.1 pg/ml), but no acceleration in gastric acid secretion was observed either in the basal condition (BAO 0.8 +/- 0.7 mEq/h) or following tetragastrin stimulation (MAO 9.0 +/- 6.9 mEq/h). Our results were inconsistent with the previous reports that high frequencies of peptic ulcers and increased gastric acid secretion were observed in patients with chronic renal failure. Our data suggest that the defensive factors rather than the aggressive factors of the gastroduodenal mucosa may be involved in chronic renal failure.

In 1983, we initiated experimental and clinical studies of endoscopic Nd:YAG laser treatment with SLT contact probes for endoscopy comparing with the non-contact quartz fiber, in order to evaluate the histological effects and safety to each method. The first computer-controlled endoscopic loval hyperthermia (Laserthermia) system was developed and reported at the 6th Meeting of the Japanease SOciety for Laser Medicine in Sep. 1985. We named interstitial local hyperthermia with Nd:YAG laser, "Laserthermia". Recent 3 years, technical and histological studies for treatment of the gastric cancer were carried out and reported in the SPIE's symposium. In this paper, newly developed the single channel method, and histological studies by Laserthermia to the human gastric cancer transplanted to the nude mice were discussed.

In this paper, we discuss the possibilities of the clinical application of the contact method with various endoprobes, either alone or combination with other conventional treat ment such as endoscopic polypectomy, local injection therapy, intubation of prosthesis, radiation therapy and general chemotherapy. According to the type of lesions and the severity of the complicated diseases, endoscopic techniques were chosen and combined. It was generally recognized that all of the endoscopic treatments were not curative therapies but applied as local therapeutics. Therefore, during the management of high risk patients with GI cancer within the mucosa, contact endoscopic Nd:YAG laser therapy should be preferred to general surgery.

We have been studying endoscopic Nd-YAG laser therapies since 1979. In consequence, advantages of the contact method by using ceramic endoprobes were revealed 123 . Various endoprobes were developed by our studies, and the experimental studies and clinical applications of ceramic frosted probe and chisel probe with Nd-YAG laser were studied. Frosted probe was able to thrombose in the artery of the canine gastric submucosal layer by Nd-YAG laser irra-diation, and was applied to endoscopic hemostasis. Chisel probe was able to cut canine gastric mucosa at the power of 20watts and duration of 2.Osec. with Nd-YAG laser, and was applied to endoscopic pyloroplasty and cutting complete biopsy of submucosal tumor.

It is generally recognized that fiberoptic endoscopy has both diagnostic and therapeutic uses and is one of the most common procedures in clinical gastroenterology. In the last decade, several endoscopic modalities for the treatment of gastrointestinal hemorrhage and neoplasms have been applied clinically. They include laser irradiation,1–5 electrocoagulation,6 topical injection, sclerotherapy, thermoprobes,7 and intubation of prosthesis.8 All of these procedures naturally have both advantages and disadvantages. Laser endoscopy is an unique procedure. Since the middle 1970s, Nd:YAG lasers have been applied using the noncontact method with the optical quartz fiber.1–5,8,9 There are distinct disadvantages of noncontact irradiation, such as the difficulty in keeping a constant distance from the tip of the quartz fiber to the lesion, allowing reliable tissue changes to occur related to the applied power. Furthermore, the quartz tip will be damaged when it comes into contact with tissue or blood. To overcome these disadvantages, the SLT contact method® with SLT endoprobes® directly connected to the quartz fiber was developed following reports of experimental research with the surgical probe, which was made of new ceramic materials.10–12 We initiated experimental and clinical studies of endoscopic Nd:YAG laser therapy, comparing the new SLT contact ceramic endoprobes with the single noncontact quartz fiber endoprobes, in order to evaluate the histologic effects and safety of each method. In this chapter, we discuss the possibilities of the clinical application of SLT contact endoprobes as a new endoscopic modality in the gastrointestinal tract.13–16