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Yousuke Nakai

Publications and source records attributed to Yousuke Nakai.

10 recordsLinked to original sources
PubMed2026

Development and Crossover Evaluation of an Artificial Intelligence-Assisted System for Solid Pancreatic Lesion Detection and Pancreatic Parenchyma Recognition in Endoscopic Ultrasonography (With Video).

BACKGROUND AND STUDY AIMS: Pancreatobiliary endoscopic ultrasonography (EUS) is technically demanding, and supervised training opportunities are limited. We developed an artificial intelligence (AI) overlay system for detecting solid pancreatic lesions (SPL) and recognizing pancreatic parenchyma (PP) and evaluated its effect on reader performance. PATIENTS AND METHODS: Across six centers, two deep learning-based models were trained using expert-annotated EUS frames. We then conducted a randomized, two-sequence, two-period crossover reader study in which eight endosonographers (five novices and three experts) interpreted image sets with and without AI assistance. The primary endpoint was superiority of sensitivity for SPL detection among novices; key secondary endpoints included specificity and PP recognition. RESULTS: From 118 patients, 120 SPL-positive/negative image sets and 160 PP-positive/negative image sets were constructed. Among novices, AI assistance improved SPL detection sensitivity (88.7% vs. 76.8%, p&#x2009;<&#x2009;0.001) and accuracy (86.4% vs. 78.7%), while specificity met the predefined noninferiority criterion (84.2% vs. 80.5%, p&#x2009;<&#x2009;0.001). For PP recognition, sensitivity increased numerically (86.3% vs. 83.3%) but did not meet the predefined superiority criterion (p&#x2009;=&#x2009;0.095); specificity met the noninferiority criterion (87.8% vs. 81.0%), and accuracy increased from 82.1% to 87.0%. Among experts, sensitivity was maintained for both tasks, whereas specificity increased with AI assistance. CONCLUSIONS: AI assistance improved SPL detection among novice endosonographers. For PP recognition, sensitivity increased without reaching statistical superiority, whereas specificity met the predefined noninferiority criterion. These findings support a potential adjunctive role for AI in EUS interpretation.

Humans↗
PubMed2006

Endoscopic management of biliary complications after adult living donor liver transplantation.

OBJECTIVES: Biliary complications are one of the important issues to be addressed after liver transplantation. Endoscopic management of biliary complications after deceased donor liver transplantation (DDLT) is widely accepted, but it remains to be established in patients after living donor liver transplantation (LDLT). Endoscopic management in LDLT patients is difficult mainly because of the complexity of duct-to-duct reconstruction. METHODS: A total of 174 adult LDLTs with duct-to-duct reconstruction were performed in our institution. Biliary complications developed in 53 patients (30%). Among these, 18 patients were referred for endoscopic management and were the subjects of the present study. Success rate, early morbidity, and outcome were evaluated in these 18 patients. RESULTS: The type of graft was the right liver in six, left liver in eight, and right lateral sector in four patients. Ten out of 18 patients had one biliary anastomosis and the remaining eight had multiple anastomoses. Six patients had a previous history of surgical or percutaneous intervention for biliary complications after LDLT. Seventeen patients had one or more biliary strictures. Biliary casts were found in nine patients, three of whom had concomitant bile leaks. Strictures were successfully treated with endoscopic balloon dilation in 12 (71%) of the 17 patients (nasobiliary catheter placement in eight and stent placement in four patients). Bile leak was successfully managed in two of three patients. Biliary casts were removed by endoscopic papillary balloon dilation in eight of nine patients. Five patients with failed endoscopic therapy were converted to percutaneous or surgical intervention. Endoscopic-procedure-related cholangitis developed in one patient. During follow-up with median periods of 10 months (range 2-20 months), four of nine patients without stent placement developed biliary strictures, and these were relieved by additional endoscopic management. CONCLUSIONS: Endoscopic approach has the potential to be a first-line therapy for the management of biliary complications after LDLT.

Adult↗
PubMed2006

Cholecystitis after metallic stent placement in patients with malignant distal biliary obstruction.

BACKGROUND & AIMS: Cholecystitis after metallic stent (MS) placement is an issue requiring attention. From our experience, cholecystitis seemed to occur mainly in patients with tumor involvement to the cystic duct orifice. The aim of the present study was to identify risk factors for cholecystitis in patients treated with covered or uncovered MS. METHODS: We analyzed 246 patients who received MS placement (covered MS in 171 and uncovered in 75) between August 1997 and May 2005 for the treatment of unresectable distal malignant biliary obstruction. Causative diseases were as follows: pancreatic cancer in 162, papillary cancer in 10, bile duct cancer in 41, and metastatic nodes in 33 patients. Tumor involvement to orifice of the cystic duct (OCD) was diagnosed based on cholangiography and intraductal ultrasonography. RESULTS: Cholecystitis after MS placement was found in 13 patients (5.3%). There was no significant difference in the incidence of cholecystitis between covered (5.8%) and uncovered (4.0%) MS. By univariate analysis, tumor involvement of the OCD, MS placed above the papilla, and stricture located at midportion were associated significantly with cholecystitis. By multivariate analysis, only tumor involvement of the OCD was a risk factor, with an odds ratio of 47.206 (95% confidence interval, 5.84-381.60). CONCLUSIONS: Cholecystitis after MS placement is associated with tumor involvement to the orifice of the cystic duct, regardless of the type of stent.

Aged↗
PubMed2006

Serum IgG4 concentrations in pancreatic and biliary diseases.

BACKGROUND: Recently, it has been reported that the serum concentration of IgG4, a minor component of IgG subclasses, is increased in autoimmune pancreatitis. However, data regarding IgG4 concentrations in other pancreatic or biliary diseases have been insufficient. METHODS: Serum IgG4 was measured in 116 patients with pancreatic or biliary diseases (35 autoimmune pancreatitis, 24 chronic pancreatitis except autoimmune pancreatitis, 11 primary sclerosing cholangitis, 23 pancreatic cancer, 3 islet cell tumor, 2 papilla cancer, 15 bile duct cancer, and 3 gallbladder cancer patients). The cut-off concentration of IgG4 was 135 mg/dl. RESULTS: Increased serum IgG4 was observed in 33 of 35 patients with autoimmune pancreatitis, 0 of 24 with chronic pancreatitis, 4 of 11 with primary sclerosing cholangitis, 0 of 23 with pancreatic cancer, 0 of 3 with islet cell tumor, 0 of 2 with duodenal papilla cancer, 0 of 15 with bile duct cancer and 0 of 3 with gallbladder cancer patients. CONCLUSIONS: Serum IgG4 was increased in autoimmune pancreatitis and was within normal limits for other pancreatic or biliary diseases except primary sclerosing cholangitis.

Adolescent↗
PubMed2006

Efficacy of peppermint oil as an antispasmodic during endoscopic retrograde cholangiopancreatography.

BACKGROUND: During endoscopic retrograde cholangiopancreatography (ERCP), hyoscine-N-butylbromide (Buscopan) or glucagon is used to inhibit duodenal motility. However, they may cause adverse effects. Peppermint oil has an antispasmodic effect and is used as a less hazardous antispasmodic during colonoscopy and upper gastrointestinal endoscopy. The purpose of the present paper was therefore to investigate peppermint as an antispasmodic for ERCP. METHODS: Forty patients were enrolled prospectively. They were assigned to four groups according to the peppermint oil concentration and site of administration: group 1, 20 mL of 1.6% solution around duodenal papilla; group 2, 20 mL of 1.6% solution both to the antrum of the stomach and around the duodenal papilla; group 3, 20 mL of 3.2% solution around the duodenal papilla; and group 4, 3.2% solution both to the antrum and around the duodenal papilla. Glucagon or hyoscine-N-butylbromide was added when duodenal peristalsis was not adequately diminished. Sixteen patients undergoing ERCP with glucagon were employed as historical controls. RESULTS: The ERCP was attempted in all except one patient in group 2 who had bleeding from invaded tumor to the duodenum. Peppermint administration equally reduced duodenal motility in the groups. Duodenal movement was none or mild in 69.2% of patients. The ERCP was successfully performed with peppermint alone in 91.4% of patients (37/39). Glucagon or hyoscine-N-butylbromide was needed in one patient each in groups 1 and 4. Serious complications related to peppermint oil did not occur. Inhibitory effect of peppermint appears to be identical to that of glucagon. CONCLUSION: Duodenal relaxation was obtained with 20 mL of 1.6% peppermint oil solution in the duodenum, but additional administration may be required. Peppermint oil is useful as an antispasmodic agent for ERCP.

Adult↗
PubMed2005

Efficacy and safety of the covered Wallstent in patients with distal malignant biliary obstruction.

BACKGROUND: The aim of this study was to evaluate the efficacy and the safety of the covered Wallstent, a commercially available silicone-covered, self-expandable metallic stent (covered Wallstent), for the treatment of distal malignant biliary obstruction. METHODS: Sixty-nine consecutive patients with unresectable distal malignant biliary obstruction who underwent covered Wallstent placement between October 2001 and October 2003 were studied at 4 affiliated hospitals. RESULTS: Mean stent patency and mean survival were 139.1 days and 200.9 days, respectively. Stent occlusion occurred in 7 cases (10.1%), but tumor ingrowth was not observed. Seventeen complications, including 5 cholangitis (7.2%), 4 stent migration (5.8%), 4 cholecystitis (5.8%), and 4 pancreatitis (5.8%) were observed in 16 patients (23.2%). Stent misplacement was observed in 7 patients (10.1%). CONCLUSIONS: Covered Wallstent is effective in preventing tumor ingrowth for the treatment of distal malignant biliary obstruction. However, the overall complication rate may be higher than uncovered self-expanding metal stents and covered self-expanding metal stents of different design.

Adult↗
PubMed2005

Ulinastatin for pancreatitis after endoscopic retrograde cholangiopancreatography: a randomized, controlled trial.

BACKGROUND & AIMS: Pancreatitis remains the major complication of endoscopic retrograde cholangiopancreatography (ERCP), and hyperenzymemia after ERCP is common. Because ulinastatin, a protease inhibitor, has proved effective in the treatment of acute pancreatitis, the aim of this study was to assess the efficacy of ulinastatin for the prevention of post-ERCP pancreatitis and hyperenzymemia. METHODS: In a multicenter, randomized, double-blind, placebo-controlled trial, patients undergoing a first ERCP were randomized to receive ulinastatin (150,000 U) or placebo by intravenous infusion for 10 minutes starting immediately before ERCP. All patients were hospitalized at least 24 hours after ERCP for evaluation of clinical symptoms. Serum pancreatic enzyme levels were measured before and at 4 and 18 hours after ERCP. The primary end point was the incidence of post-ERCP pancreatitis and the secondary objective was the occurrence of hyperenzymemia. RESULTS: A total of 406 patients were enrolled (204 in the ulinastatin group and 202 in the placebo group). There were no differences between the 2 groups regarding baseline characteristics, details of fluoroscopic findings, or endoscopic procedure. The incidence of hyperenzymemia was significantly lower in the ulinastatin group than in the placebo group (amylase, P = .011; lipase, P = .008). Six patients in the ulinastatin group and 15 patients in the placebo group developed pancreatitis (2.9% vs. 7.4%, P = .041). There was no case of severe pancreatitis in either group. Patients who received ulinastatin did not present any side effects related to the medication. CONCLUSIONS: Prophylactic short-term administration of ulinastatin decreases the incidence of pancreatitis and hyperenzymemia after ERCP.

Acute Disease↗
PubMed2005

Identifying genes with differential expression in gemcitabine-resistant pancreatic cancer cells using comprehensive transcriptome analysis.

Pancreatic cancer is often unresectable at diagnosis, and chemotherapy using gemcitabine is now the standard treatment for advanced pancreatic cancer. However, acquired resistance to gemcitabine resulting in therapeutic failure is often encountered. Therefore, we sought to identify genes that determine gemcitabine resistance by evaluating the relationship between gene expression profiles and gemcitabine sensitivity to provide molecular targets for overcoming gemcitabine resistance. First, the gemcitabine concentration needed for 50% growth inhibition was examined in six pancreatic cancer cell lines. By exposing MIA PaCa-2 cells to long-term gemcitabine, we established gemcitabine-resistant cells. The gene expression profiles of the six pancreatic cancer cell lines and gemcitabine-resistant cells were determined using cDNA microarray analysis. By comparing the results, 30 genes were identified as differentially expressed genes correlated with gemcitabine sensitivity. Differentially expressed genes in the parental cell lines were also examined, and six overlapping genes were identified as genes correlated with gemcitabine sensitivity in both assays. Of these genes, the down-regulated expression of TNFSF6 protein, also known as Fas ligand, was confirmed in the gemcitabine-resistant cell line. These results should provide therapeutic molecular targets for overcoming gemcitabine resistance.

Antimetabolites, Antineoplastic↗
PubMed2004

Pancreatic mass lesions associated with raised concentration of IgG4.

Autoimmune pancreatitis (AIP) is a recognized benign disease characterized by irregular narrowing of the pancreatic duct, swelling of parenchyma, lymphoplasmacytic infiltration and fibrosis, and a favorable response to corticosteroid treatment. In this condition, the whole pancreas is diffusely affected. Recently, however, a few cases with locally affected lesions were reported, with some of them showing features similar to cancer. We reviewed 138 patients with pancreatic mass lesion, of which 17 were not initially diagnosed despite examinations. Serum IgG4 levels were elevated in seven of them. Their biopsy specimens had a similar appearance to those of AIP. We considered that they should be diagnosed as AIP or conditions related to AIP. Among the 10 patients without elevated IgG4, 4 patients were diagnosed as pancreatic cancer after follow-up, 1 presented with an islet cell tumor, 1 presented AIP with sclerosing cholangitis, and the other 4 had chronic pancreatitis.

Adult↗