Yoji Sanomura

RISK FACTORS FOR BLEEDING AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION OF GASTRIC EPITHELIAL NEOPLASM

Background:  Although endoscopic submucosal dissection (ESD) is standard therapy in Japan for gastric epithelial neoplasm, the complication rate is unsatisfactory, with postoperative bleeding as the major complication. The aim of the present study was to determine risk factors for post‐ESD bleeding in patients with gastric epithelial neoplasm.

Endoscopic submucosal dissection for residual early gastric cancer after endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) has become a standard treatment for early gastric cancer (EGC). 1-12 ESD involves circumferential mucosal incision and direct submucosal dissection, making it possible to resect en bloc even large tumors with endoscopically clear margins in any part of the stomach. The reported incomplete ESD resection rate is 7.4% to 26.3%, 1,2,13-19 and the reported local recurrence rate after ESD is 0% to 3%. 1,18-20 Incomplete resection leading to recurrent cancer in the stomach therefore continues to be problematic. Additional treatment is necessary in patients with incompletely resected lesions. We have reported ESD for residual/local recurrent EGC after EMR to be a safe, minimally invasive, effective procedure. 21 There are few published reports on the treatment of local recurrences of EGC after ESD, and it is difficult to carry out a second ESD because of scar formation resulting from the initial ESD. Between June 2005 and August 2012, we performed a second ESD in 12 patients with residual EGC lesions after having been treated with ESD, and we conducted a retrospective evaluation of the safety and efficacy of this method of treatment.

A computer system to be used with laser-based endoscopy for quantitative diagnosis of early gastric cancer.

Goals: To evaluate the usefulness of a newly devised computer system for use with laser-based endoscopy in differentiating between early gastric cancer, reddened lesions, and surrounding tissue. Background: Narrow-band imaging based on laser light illumination has come into recent use. We devised a support vector machine (SVM)-based analysis system to be used with the newly devised endoscopy system to quantitatively identify gastric cancer on images obtained by magnifying endoscopy with blue-laser imaging (BLI). We evaluated the usefulness of the computer system in combination with the new endoscopy system. Study: We evaluated the system as applied to 100 consecutive early gastric cancers in 95 patients examined by BLI magnification at Hiroshima University Hospital. We produced a set of images from the 100 early gastric cancers; 40 flat or slightly depressed, small, reddened lesions; and surrounding tissues, and we attempted to identify gastric cancer, reddened lesions, and surrounding tissue quantitatively. Results: The average SVM output value was 0.846±0.220 for cancerous lesions, 0.381±0.349 for reddened lesions, and 0.219±0.277 for surrounding tissue, with the SVM output value for cancerous lesions being significantly greater than that for reddened lesions or surrounding tissue. The average SVM output value for differentiated-type cancer was 0.840±0.207 and for undifferentiated-type cancer was 0.865±0.259. Conclusions: Although further development is needed, we conclude that our computer-based analysis system used with BLI will identify gastric cancers quantitatively.

Predicting the absence of lymph node metastasis of submucosal invasive gastric cancer: Expansion of the criteria for curative endoscopic resection

Abstract Objective. The conditions upon which endoscopic resection (ER) can be considered curative for submucosal invasive gastric cancer remain controversial; thus, unnecessary surgery is sometimes performed after ER. Our purpose is to evaluate the significance of several clinicopathological factors for predicting the absence of lymph node (LN) metastasis of submucosal invasive gastric cancer and thus determining cases in which ER can be considered curative. Patients and methods. The study group comprised 220 patients with submucosal invasive gastric cancer that was resected surgically or endoscopically. Patients treated by ER underwent additional surgical resection. The presence of LN metastasis was evaluated in all patients, retrospectively. Results. LN metastasis was detected in 37 (16.8%) of the 220 patients. Independent risk factors for LN metastasis were width of submucosal invasion >6000 μm, lymphatic involvement, undifferentiated type at the deepest invasive portion, depth of submucosal invasion >1000 μm, and tumor diameter >30 mm. The group of 36 patients with submucosal invasion to a depth of ≤1000 μm, tumor diameter ≤30 mm, differentiated type as the dominant histologic type, and absence of vessel involvement was entirely free of LN metastasis (95% confidence interval, 0–8.0%). Conclusions. Taken together, the five independent risk factors may allow expansion of the criteria for determining whether ER for submucosal invasive gastric cancer has been curative.

Clinical outcomes of endoscopic submucosal dissection for early gastric cancer in patients with chronic kidney disease

Endoscopic submucosal dissection (ESD) is a widely accepted treatment for early gastric cancer (EGC), and the number of ESD performed for EGC in patients with chronic kidney disease (CKD) is increasing. Although patients undergoing hemodialysis tend to bleed and are at high risk for cardiovascular disease, the effectiveness and safety of ESD for EGC in patients with CKD in particular have not been established. The aim of this study was to evaluate the effectiveness and potential adverse effects of ESD for EGC in patients with CKD undergoing hemodialysis.

Calibration of a 3D endoscopic system based on active stereo method for shape measurement of biological tissues and specimen.

For endoscopic medical treatment, measuring the size and shape of the lesion, such as a tumor, is important for the improvement of diagnostic accuracy. We are developing a system to measure the shapes and sizes of living tissue by active stereo method using a normal endoscope on which a micro pattern projector is attached. In order to perform 3D reconstruction, estimating the intrinsic and extrinsic parameters of the endoscopic camera and the pattern projector is required. Particularly, calibration of the pattern projector is difficult. In this paper, we propose a simultaneous estimation method of both intrinsic and extrinsic parameters of the pattern projector. This simplifies the calibration procedure required in practical scenes. Furthermore, we have developed an efficient user interface to intuitively operate the calibration and reconstruction procedures. Using the developed system, we measured the shape of an internal tissue of the soft palate of a human and a biological specimen.

Quantitative identification of mucosal gastric cancer under magnifying endoscopy with flexible spectral imaging color enhancement

Magnifying endoscopy with flexible spectral imaging color enhancement (FICE) is clinically useful in diagnosing gastric cancer and determining treatment options; however, there is a learning curve. Accurate FICE‐based diagnosis requires training and experience. In addition, objectivity is necessary. Thus, a software program that can identify gastric cancer quantitatively was developed.

Characteristics of Metachronous Gastric Tumors after Endoscopic Submucosal Dissection for Gastric Intraepithelial Neoplasms

Background. Recently, endoscopic submucosal dissection (ESD) has become a standard treatment method for early gastric cancer and concurrent stomach preservation. However, metachronous recurrences have become a major problem. We evaluated the incidence and clinicopathologic features of and examined the risk factors for metachronous gastric tumors. Methods. A total of 357 patients who underwent ESD for gastric tumors (245 early gastric cancers and 112 adenomas) and were followed up for more than 12 months without recurrence within the first 12 months were enrolled. We investigated the incidence and clinicopathologic features of metachronous tumors after ESD. We also analyzed the potential risk factors for metachronous tumors using the Kaplan-Meier method and Coxs proportional hazards model. Results. The annual incidence of metachronous tumors after ESD was 2.4%. The median period until discovery after initial ESD was 26.0 months, and the median observation period was 52.6 months. Male patients developed metachronous tumors more frequently (P = 0.04), and the hazard ratio of female to male patients was 0.36 (95% confidence interval: 0.11–0.89). Conclusions. Patients with a previous history of gastric tumors have a high risk of subsequent gastric tumor development and male patients should be carefully followed up after ESD for gastric tumor.

3D endoscope system using DOE projector

For effective in situ endoscopic diagnosis and treatment, size measurement and shape characterization of lesions, such as tumors, is important. For this purpose, in the past we have developed a range of 3D endoscopic systems based on active stereo to measure the shape and size of living tissues. In those works, the main shortcoming was that the target area could only be reconstructed at a specific distance from the scope because of off-focus blurring effects and aberrations in the periphery of the field of view. These issues were compounded by the degree of reconstruction instability due to the strong subsurface scattering common in internal tissue. In this paper, we tackle these shortcomings by developing a new micro pattern laser projector to be inserted in the scope tool channel. The new projector uses a Diffractive Optical Element (DOE) instead of a single lens, which solves the off-focus blur. We also propose a new line-based grid pattern with gap coding to counter the subsurface scattering effect. In our experiments on ex vivo human tumor samples, we show that the tissue shapes were successfully reconstructed regardless of depth variance and strong subsurface scattering effects.

Proposal on 3-D endoscope by using grid-based active stereo

In this paper, we propose a novel 3-D endoscope system by using grid-based active stereo. In the proposed system, projection of a waved-grid pattern that consists of vertical and horizontal sinusoidal lines realizes accurate shape acquisition in sub-pixel accuracy. We develop a small pattern projector implementable to a head of a ready-made endoscope, and examine 3-D shape reconstruction by actual equipment. As the result of the measurement for a known-shaped object, which is a hexagonal cylinder, the error of length measurement is below 0.9% and the error of angle measurement is below 2.2%. We make a measurement of animal organ meat, and confirm that the system can reconstruct a 3-D shape of the organ surface.