21 세기 침탄열처리 기술의 발전 전망 : Challengers for the Next Century

Naitoh, Takeshi,정태영,김한군 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.2

Optimal endoscopic drainage strategy for unresectable malignant hilar biliary obstruction

Itaru Naitoh,Tadahisa Inoue 대한소화기내시경학회 2023 Clinical Endoscopy Vol.56 No.2

Endoscopic biliary drainage strategies for managing unresectable malignant hilar biliary obstruction differ in terms of stent type, drainage area, and deployment method. However, the optimal endoscopic drainage strategy remains unclear. Uncovered self-expandable metal stents (SEMS) are the preferred type because of their higher functional success rate, longer time to recurrent biliary obstruction (RBO), and fewer cases of reintervention than plastic stents (PS). Other PS subtypes and covered SEMS, which feature a longer time to RBO than PS, can be removed during reintervention for RBO. Bilateral SEMS placement is associated with a longer time to RBO and a longer survival time than unilateral SEMS placement. Unilateral drainage is acceptable if a drainage volume of greater than 50% of the total liver volume can be achieved. In terms of deployment method, no differences were observed in clinical outcomes between side-by-side (SBS) and stent-in-stent deployment. Simultaneous SBS boasts a shorter procedure time and higher technical success rate than sequential SBS. This review of previous studies aimed to clarify the optimal endoscopic biliary drainage strategy for unresectable malignant hilar biliary obstruction.

Classification and Diagnostic Criteria for IgG4-Related Sclerosing Cholangitis

( Itaru Naitoh ),( Takahiro Nakazawa ) 대한소화기학회 2022 Gut and Liver Vol.16 No.1

IgG4-related sclerosing cholangitis (IgG4-SC) can be classified into four types based on cholangiographic findings and regions of biliary stricture. This cholangiographic classification is useful to differentiate IgG4-SC from mimickers including cholangiocarcinoma, primary sclerosing cholangitis, and pancreatic cancer. Autoimmune pancreatitis (AIP) is a valuable clue for the diagnosis of IgG4-SC because the two are frequently found in association with each other. Two sets of diagnostic criteria for IgG4-SC have been proposed. In Japan, the clinical diagnostic criteria 2020 were recently developed. These clinical diagnostic criteria include narrowing of the intrahepatic and/or extrahepatic bile duct, thickening of the bile duct wall, serological findings, pathological findings, other organ involvement, and effectiveness of steroid therapy. When these criteria are applied, IgG4-SC is initially classified as associated or not associated with AIP, and cholangiographic classification is used for differential diagnosis. In most instances, IgG4-SC can be diagnosed on the basis of clinical diagnostic criteria. However, it is challenging to diagnose isolated IgG4-SC or IgG4-SC not associated with AIP. Here, we review the classification and diagnostic criteria for IgG4-SC, specifically focusing on the clinical diagnostic criteria 2020 and a large IgG4-SC case series from a nationwide survey in Japan. (Gut Liver 2022;16:28-36)

Which is better for unresectable malignant hilar biliary obstruction: Side-by-side versus stent-in-stent?

Itaru Naitoh,Tadahisa Inoue,Kazuki Hayashi 소화기인터벤션의학회 2018 International journal of gastrointestinal interven Vol.7 No.2

Biliary drainage is required for the management of unresectable malignant hilar biliary obstruction (UMHBO), and endoscopic transpapillary drainage is the first-line therapy because it is less invasive. Self-expandable metallic stents (SEMSs) are superior to plastic stents because they have longer stent patency and are more cost-effective. Endoscopic bilateral SEMS placement is technically challenging compared to unilateral placement. However, recent developments in devices and techniques have facilitated bilateral SEMS placement. There are two methods for bilateral hilar SEMS placement for UMHBO: side-by-side (SBS) and stent-in-stent (SIS). Sequential SBS was commonly conducted for bilateral hilar SEMS placement. In a new and thinner delivery system that was developed for SEM placement, two SEMSs could be simultaneously inserted and deployed through the working channel. This new bilateral stenting method enabled us to accomplish simultaneous SBS placement, which increased the success rate of SBS. Insertion of the guidewire and delivery of the second SEMS through the mesh of the first SEMS is challenging in SIS. Newly designed or modified SEMSs that are suitable for SIS have been developed to overcome this challenge, and these SEMSs have facilitated SIS. Uncovered SEMS has been commonly used for hilar SEMS placement, but covered SEMS (CSEMS) is another option for hilar SEMS placement, because CSEMS prevents tumor ingrowth and allows for removal of the stent for re-intervention. Therefore, CSEMS can be used for bilateral SEMS placement in SBS. There are many methods and kinds of SEMS available for bilateral SEMS placement. However, due to lack of evidence, there is no consensus on whether SBS or SIS is optimal for bilateral hilar SEMS placement. In this review, we compared various outcomes between SBS and SIS from previous studies, to clarify which method is better for bilateral SEMS placement for UMHBO.

Which is better for unresectable malignant hilar biliary obstruction: Side-by-side versus stent-in-stent?

Itaru Naitoh,Tadahisa Inoue,Kazuki Hayashi 소화기인터벤션의학회 2018 Gastrointestinal Intervention Vol.7 No.2

Biliary drainage is required for the management of unresectable malignant hilar biliary obstruction (UMHBO), and endoscopic transpapillary drainage is the first-line therapy because it is less invasive. Self-expandable metallic stents (SEMSs) are superior to plastic stents because they have longer stent patency and are more cost-effective. Endoscopic bilateral SEMS placement is technically challenging compared to unilateral placement. However, recent developments in devices and techniques have facilitated bilateral SEMS placement. There are two methods for bilateral hilar SEMS placement for UMHBO: side-by-side (SBS) and stent-in-stent (SIS). Sequential SBS was commonly conducted for bilateral hilar SEMS placement. In a new and thinner delivery system that was developed for SEM placement, two SEMSs could be simultaneously inserted and deployed through the working channel. This new bilateral stenting method enabled us to accomplish simultaneous SBS placement, which increased the success rate of SBS. Insertion of the guidewire and delivery of the second SEMS through the mesh of the first SEMS is challenging in SIS. Newly designed or modified SEMSs that are suitable for SIS have been developed to overcome this challenge, and these SEMSs have facilitated SIS. Uncovered SEMS has been commonly used for hilar SEMS placement, but covered SEMS (CSEMS) is another option for hilar SEMS placement, because CSEMS prevents tumor ingrowth and allows for removal of the stent for re-intervention. Therefore, CSEMS can be used for bilateral SEMS placement in SBS. There are many methods and kinds of SEMS available for bilateral SEMS placement. However, due to lack of evidence, there is no consensus on whether SBS or SIS is optimal for bilateral hilar SEMS placement. In this review, we compared various outcomes between SBS and SIS from previous studies, to clarify which method is better for bilateral SEMS placement for UMHBO.

Usefulness of Intraductal Ultrasonography in the Diagnosis of Cholangiocarcinoma and IgG4-Related Sclerosing Cholangitis

Takahiro Nakazawa,Itaru Naitoh,Kazuki Hayashi 대한소화기내시경학회 2012 Clinical Endoscopy Vol.45 No.3

The technique of intraductal ultrasonography (IDUS) of the bile duct with a thin-caliber probe and a ropeway system has provided excellent images of the bile duct and periductal structures and is an easy transpapillary approach. In addition, once the guide wire is inserted into the bile duct, IDUS and transpapillary biopsy after endoscopic retrograde cholangiopancreatography can be performed in a single session. Here, we review the usefulness of IDUS in the diagnosis of cholangiocarcinoma and IgG4-related sclerosing cholangitis.

Flow-Field Produced by a Vortex Ring Travelling across a Thin Circular Cylinder

H. Yamada,T. Naitoh 대한기계학회 1990 KSME/JSME THERMAL and FLUID Engineering Conference Vol.2 No.1

Four-Step Classification of Endoscopic Transpapillary Gallbladder Drainage and the Practical Efficacy of Cholangioscopic Assistance

( Michihiro Yoshida ),( Itaru Naitoh ),( Kazuki Hayashi ),( Naruomi Jinno ),( Yasuki Hori ),( Makoto Natsume ),( Akihisa Kato ),( Kenta Kachi ),( Go Asano ),( Naoki Atsuta ),( Hidenori Sahashi ),( Hir 대한소화기학회 2021 Gut and Liver Vol.15 No.3

Background/Aims: Although endoscopic transpapillary gallbladder drainage (ETGBD) has been reported as an alternative procedure for acute cholecystitis, it requires advanced endoscopic techniques. In terms of the certainty of achieving drainage, it remains a challenging procedure. The aim of the current study was to elucidate the practical efficacy of cholangioscopic assistance and to develop a new classification that could be used to evaluate the technical difficulty of ETGBD and provide a theoretical strategy to apply cholangioscopy appropriately for difficult ETGBD. Methods: A total of 101 patients undergoing ETGBD were retrospectively studied. The characteristics and technical outcomes of ETGBD with conventional ETGBD (C-ETGBD) and Spy- Glass DS-assisted ETGBD (SG-ETGBD) were evaluated. The characteristics and technique-dependent factors of unsuccessful C-ETGBD/SG-ETGBD were evaluated using the classification based on the steps of the procedure. The predictive factors of successful C-ETGBD/SG-ETGBD were examined. Results: C-ETGBD was successful in 73 patients (72.3%). SG-ETGBD was successful in 11 of 13 patients (84.6%) who had C-ETGBD failure. Optional SG-ETGBD significantly increased the final success rate (94.1%) compared to C-ETGBD alone (p=0.003). ETGBD procedures could be classified into four steps. SG-assistance worked as an excellent troubleshooter in step 1 (failure to identify the cystic duct orifice) and step 2 (failure of guidewire advancement across the downturned angle of cystic duct takeoff). Magnetic resonance cholangiopancreatography could provide predictive information based on the classification. Conclusions: Optional SG-ETGBD achieved a significantly higher success rate than C-ETGBD alone. Step classification is helpful for determining the technical difficulty of ETGBD and developing a theoretical strategy to apply cholangioscopy in a coordinated manner. (Gut Liver 2021;15:476-485)

CONTROL STRATEGIES FOR AC/DC MOTOR DRIVES

Susuma TAKAKUMA,Haruo NAITOH,Isao MORI,Shinji TATARA 전력전자학회 1989 ICPE(ISPE)논문집 Vol.- No.-

A survey on the state of art of the application of modern control theory is presented. The historical background and general features of the theory are described as an introduction. It is followed by overview of papers on the subject with respect to various aspects of ac/dc motor drives. Three examples applied to the vector controlled induction motors are briefed for materialized idea.

Dryout of Water Film on a Heated Tube Surface Caused by an Obstruction in a Boiling Two-Phase Vertical Upward Flow in an Annular Channel ( Effect of an Upstream Spacer )

Tohru Fukano,Kouji Naitoh,Shizu Akamatsu 대한기계학회 1998 Heat transter conference Vol.2 No.1