Kouichi Hamabe

Usefulness of magnifying endoscopy with narrow-band imaging for determining gastric tumor margin.

Background and Aim:  Magnifying endoscopy with narrow‐band imaging (ME‐NBI) enhances images of the irregular mucosal structures and microvessels of gastric carcinoma, and could be useful for determining the margin between cancerous and non‐cancerous mucosa. We evaluated the usefulness of ME‐NBI for determining the tumor margin compared with indigocarmine chromoendoscopy (ICC).

New method for detection of gastric cancer by hyperspectral imaging: a pilot study

Abstract. We developed a new, easy, and objective method to detect gastric cancer using hyperspectral imaging (HSI) technology combining spectroscopy and imaging A total of 16 gastroduodenal tumors removed by endoscopic resection or surgery from 14 patients at Yamaguchi University Hospital, Japan, were recorded using a hyperspectral camera (HSC) equipped with HSI technology Corrected spectral reflectance was obtained from 10 samples of normal mucosa and 10 samples of tumors for each case The 16 cases were divided into eight training cases (160 training samples) and eight test cases (160 test samples) We established a diagnostic algorithm with training samples and evaluated it with test samples Diagnostic capability of the algorithm for each tumor was validated, and enhancement of tumors by image processing using the HSC was evaluated The diagnostic algorithm used the 726-nm wavelength, with a cutoff point established from training samples The sensitivity, specificity, and accuracy rates of the algorithm’s diagnostic capability in the test samples were 78.8% (63/80), 92.5% (74/80), and 85.6% (137/160), respectively Tumors in HSC images of 13 (81.3%) cases were well enhanced by image processing Differences in spectral reflectance between tumors and normal mucosa suggested that tumors can be clearly distinguished from background mucosa with HSI technology.

Role of DNA methylation in the development of Epstein–Barr virus-associated gastric carcinoma†

The frequencies of DNA methylation of certain tumor‐related genes are higher in Epstein–Barr virus (EBV)‐associated gastric carcinomas than in EBV‐negative gastric carcinomas. EBV‐associated gastric carcinomas have distinct clinicopathological features; however, there are no case‐control studies comparing methylation frequency between EBV‐associated gastric carcinomas and controls that have been adjusted according to the clinicopathological features of EBV‐associated gastric carcinomas. This study evaluated 25 EBV‐associated gastric carcinomas that were positive for EBV‐encoded small RNA 1 (EBER‐1) by in situ hybridization and 50 EBV‐negative gastric carcinomas that were matched with the EBV‐associated gastric carcinomas by age, sex, histology, depth of tumor invasion, and stage. Methylation status of 16 loci associated with tumor‐related genes was analyzed by methylation‐specific polymerase chain reaction (PCR) to identify genes in which DNA methylation specifically occurred in EBV‐associated gastric carcinomas. Methylation frequencies of 12 of the 16 genes were higher in EBV‐associated gastric carcinomas than in EBV‐negative controls, and the frequency of methylation of 6 specific loci (MINT2, MINT31, p14, p16, p73, and RUNX3) was significantly higher in EBV‐associated gastric carcinomas than in EBV‐negative controls. There were no significant differences in the methylation frequencies of the other genes. The mean methylation index in EBV‐associated gastric carcinomas was significantly higher than that in EBV‐negative controls. DNA methylation of tumor suppressor genes that regulate the cell cycle and apoptosis specifically occurred in EBV‐associated gastric carcinomas. Aberrant DNA methylation might lead to the development and progression of EBV‐associated gastric carcinoma. J. Med. Virol. 85:121–127, 2012.

Risk factors for delayed bleeding from endoscopic submucosal dissection of gastric neoplasms

Abstract Objective. Delayed bleeding is a major complication of endoscopic submucosal dissection (ESD) of gastric neoplasms. We aimed to clarify risk factors for delayed bleeding from ESD. Material and methods. This study included 447 patients in whom 544 gastric neoplasms were resected by ESD between April 2006 and March 2011 in Yamaguchi University Hospital. We analyzed risk factors for delayed bleeding from ESD in relation to various clinical and pathological factors. Results. En bloc resection rate was 95.4% (519/544), and curative resection rate was 87.8% (477/544). Delayed bleeding occurred in 7.0% (38/544) and perforation occurred in 1.8% (10/544) of patients. Univariate analysis revealed platelet count (Plt) <15 × 104/μl (p = 0.013), prothrombin time (PT) <70% (p = 0.044), resected size ≥50 mm (p = 0.038), and positive/indeterminate lateral margin (p = 0.012) to be risk factors for delayed bleeding. Multivariate analysis showed that Plt <15 × 104/μl (odds ratio [OR], 2.62; 95% confidence interval [CI]: 1.17–5.53, p = 0.020) and positive/indeterminate lateral margin (OR, 5.45; 95% CI: 1.39–17.95, p = 0.018) were independent risk factors for delayed bleeding. Conclusions. Low Plt, low PT, large resected size, and positive/indeterminate lateral margin were significant risk factors for delayed bleeding from ESD. Patients with these risk factors must be carefully observed for signs of delayed bleeding.

Preliminary study of photodynamic diagnosis using 5-aminolevulinic acid in gastric and colorectal tumors.

AIM To investigate the utility of photodynamic diagnosis (PDD) using 5-aminolevulinic acid (5-ALA) to detect gastric/colorectal tumors. METHODS This prospective single-center study investigated inter-subject variability in patients with early-stage gastric/colorectal tumor indicated for endoscopic resection. Subjects were patients with gastric or colorectal tumors who had undergone endoscopic resection between November 2012 and November 2013. Selection criteria included age 20-80 years, either sex, and provision of informed consent. Patients were orally administered 20 mg/kg of 5-ALA enteric-coated capsules (SBI ALApromo Co., Tokyo, Japan). Administration of 5-ALA was followed by endoscopic resection of gastric or colorectal tumors, and the resected specimens were examined using a video autofluorescence processor and a fluorescence endoscope (SAFE-3000 and EB-1970AK, respectively; Pentax, Tokyo, Japan). The primary endpoint was the presence of fluorescence in tumors. Endoscopic, macroscopic, and histopathologic findings of tumors were assessed. We also evaluated adverse events of the present procedure as a secondary endpoint and examined each patient for the presence of known adverse effects of 5-ALA, namely, hematocytopenia, liver dysfunction, hypotension, nausea, and photosensitivity. RESULTS We enrolled 10 patients (7 men, 3 women) (n = 13 lesions: 10 gastric/3 colorectal tumors). Fluorescence was detected in 7/13 (53.8%) lesions. No significant differences in sex (male: 55.6% vs female: 50.5%, P = 1.00), age (67.1 ± 1.9 years vs 65.0 ± 2.0 years, P = 0.45), tumor color (reddish: 60.0% vs discolored: 33.3%, P = 0.56), tumor diameter (15.0 ± 2.1 mm vs 14.2 ± 2.3 mm, P = 0.80), macroscopic type (protruded: 70.0% vs depressed 0%, P = 0.07), histologic type (differentiated type: 58.3% vs 0%, P = 0.46), invasion depth (mucosal layer: 55.6% vs submucosal layer: 33.3%, P = 1.00), lymphatic invasion (present: 33.3% vs absent: 50.0%, P = 1.00), venous invasion (present: 0% vs absent: 54.5%, P = 1.00) or procedure time of endoscopic resection (36.3 ± 8.3 min vs 36.7 ± 9.0 min, P = 0.98) were observed between the patients with and without fluorescence. Fluorescence detection rate tended to be high for elevated lesions. Liver dysfunction developed in 4/10 (40.0%) patients. The extent of the liver dysfunction was a slight increase in transaminases and total bilirubin levels, which spontaneously improved in the patients. None of the patients developed photosensitivity. CONCLUSION Results of this preliminary study suggest the utility of PDD using 5-ALA for screening of gastric and colorectal cancers.

Efficacy of i-Scan Imaging for the Detection and Diagnosis of Early Gastric Carcinomas

We determined comparative efficacy of i-Scan for detection and diagnosis of gastric cancer. Ten patients diagnosed with early gastric cancer based on histopathological findings were analyzed. White light and i-Scan moving images recorded from these patients in twin mode were separated into white light and i-Scan. Twelve endoscopists (three different skill levels) blinded to patient information evaluated the images. Correlation between demarcation accuracy and lesion brightness on still images was investigated. No significant differences were found in diagnostic accuracy between white light and i-Scan moving images for tumor detection rate (91.7% versus 90.8%, P = 0.777). Diagnostic accuracy of tumor size was comparable between novice and experienced endoscopists for i-Scan moving images (65.7% versus 71.1%, P = 0.528), whereas it was significantly lower for white light moving images (41.2% versus 79.5%, P = 0.019). Tumor demarcation accuracy was significantly better with white light than i-Scan still images (71.0% versus 65.8%, P = 0.033). Correlations between demarcation accuracy and brightness reached highs of 0.75 for white light and 0.89 for i-Scan imaging. Efficacy of i-Scan over that of white light imaging for detecting and diagnosing gastric cancer was not shown; however, the diagnostic capability of i-Scan can be improved if imaging conditions are optimized.

Fine-tuning the criteria for strip biopsy and endoscopic submucosal dissection improves the outcome of early gastric carcinoma treatment

Background and Aim:  Strip biopsy and endoscopic submucosal dissection (ESD) have been developed as a local treatment for early gastric cancer (EGC). However, the lesion criteria for the use of ESD, rather than strip biopsy, remain to be elucidated.

Image quality of a novel light-emitting diode (LED)-illuminated colonoscope

BACKGROUND AND STUDY AIMS Light-emitting diodes (LEDs) are used widely for their high luminous efficiency and durability. We developed a novel prototype high definition endoscope with white LEDs and evaluated the image quality it produced against a commercial endoscope with conventional light source. PATIENTS AND METHODS The specifications of both colonoscopes were identical, except for the LED light source at the tip of the prototype. We examined 20 patients with rectal or sigmoid colon lesions and the image quality was evaluated in 40 images (one image from the LED colonoscope and one from the conventional colonoscope for each lesion) by three endoscopists. We additionally evaluated the 17 videos recorded with the LED colonoscope that were available. Image quality, mucosal and vascular color, and luminous distribution and intensity were scored on a 5-point scale. RESULTS The mean score for vascular color given by one evaluator was significantly higher using the LED colonoscope than using the conventional colonoscope. The mean scores for mucosal color and luminous intensity from another evaluator were significantly lower with the LED colonoscope than with the conventional colonoscope. There were no significant differences in the luminous distribution scores for any of the evaluators. The image quality of the videos was evaluated as being similar with both colonoscopes. CONCLUSIONS Image quality from the LED and conventional colonoscopes were similar, although the luminous intensity of the LEDs is inferior to that of the conventional light source at the present time.

Treatment Using the SpyGlass Digital System in a Patient with Hepatolithiasis after a Whipple Procedure

An 89-year-old man was referred to our hospital for treatment of hepatolithiasis causing recurrent cholangitis. He had undergone a prior Whipple procedure. Computed tomography demonstrated left-sided hepatolithiasis. First, we conducted peroral direct cholangioscopy (PDCS) using an ultraslim endoscope. Although PDCS was successfully conducted, it was unsuccessful in removing all the stones. The stones located in the B2 segment were difficult to remove because the endoscope could not be inserted deeply into this segment due to the small size of the intrahepatic bile duct. Next, we substituted the endoscope with an upper gastrointestinal endoscope. After positioning the endoscope, the SpyGlass digital system (SPY-DS) was successfully inserted deep into the B2 segment. Upon visualizing the residual stones, we conducted SPY-DS-guided electrohydraulic lithotripsy. The stones were disintegrated and completely removed. In cases of PDCS failure, a treatment strategy using the SPY-DS can be considered for patients with hepatolithiasis after a Whipple procedure.

Invasive inflammatory fibroid polyp of the stomach: a case report and literature review

BackgroundInflammatory fibroid polyps (IFPs) are rare mesenchymal lesions that affect the gastrointestinal tract. IFPs are generally considered benign, noninvasive lesions; however, we report a case of an invasive gastric IFP. To the best of our knowledge, this is only the second case report of an invasive gastric IFP.Case presentationA 62-year-old woman presented with complaints of epigastric pain and vomiting. Computed tomography showed a 27-mm, hyper-enhancing tumor in the prepyloric antrum. Upper endoscopy also showed a submucosal tumor causing subtotal obstruction of the gastric outlet. Because a gastrointestinal stromal tumor was suspected, distal gastrectomy was performed. Histopathological examination revealed spindle cell proliferation in the submucosal layer. The spindle cells had invaded the muscularis propria layer and extended to the subserosal layer. The tumor was finally diagnosed as an IFP based on immunohistochemical findings. No mutations were identified in the platelet-derived growth factor receptor alpha (PDGFRA) gene via molecular genetic analysis.Discussion and conclusionsAfter the discovery that IFPs often harbor PDGFRA mutations, these growths have been considered neoplastic lesions rather than reactive lesions. Based on the present case, IFPs might be considered not only neoplastic but also potentially invasive lesions.