Role of radiofrequency ablation in advanced malignant hilar biliary obstruction

Malignant hilar biliary obstruction (MHO), an aggressive perihilar biliary obstruction caused by cholangiocarcinoma, gallbladder cancer, or other metastatic malignancies, has a poor prognosis. Surgical resection is the only curative treatment for biliary malignancies. However, the majority of patients with MHO cannot undergo surgery on presentation because of an advanced inoperable state or a poor performance state due to old age or comorbid diseases. Therefore, palliative biliary drainage is mandatory to improve symptomatic jaundice and the quality of life. Among the drainage methods, endoscopic biliary drainage is the current standard for palliation of unresectable advanced MHO. In addition, combined with endoscopic drainage, additional local ablation therapies, such as photodynamic therapy or radiofrequency ablation (RFA), have been introduced to prolong stent patency and survival. Currently, RFA is commonly used as palliative therapy, even for advanced MHO. This literature review summarizes recent studies on RFA for advanced MHO

Study protocol for endoscopic ultrasonography-guided ethanol injection therapy for patients with pancreatic neuroendocrine neoplasm: a multicentre prospective study

Introduction The management of small pancreatic neuroendocrine neoplasms (PNENs) remains controversial. The standard treatment for PNENs is surgical resection; however, invasiveness of surgical procedure remains higher and the incidence of postoperative adverse events is still high. Recently, the efficacy and safety of endoscopic ultrasonography (EUS)-guided ethanol injection for small PNENs has been preliminarily demonstrated. Thus, a multicentre prospective study is being conducted to evaluate the efficacy and safety of EUS-guided ethanol injection therapy for small PNENs. Methods and analysis The major eligibility criteria are the presence of pathologically diagnosed grade (G) 1 tumour, a tumour size of <= 15 mm and non-functional PNEN or insulinoma. For treatment, we will use a 25-gauge needle and pure ethanol. Contrast-enhanced CT (CE-CT) will be performed on postoperative day 3-5, and if enhanced areas of the tumour are still apparent, an additional session is scheduled during the same hospitalisation period. We set the total amount of ethanol per session to 2 mL. To evaluate the efficacy and safety, CE-CT will be performed at 1 and 6 months after treatment. The primary endpoint is the percentage of subjects who achieved all of the following evaluated points. Efficacy will be evaluated based on the achievement of complete ablation (defined as no enhanced area within the tumour on CE-CT) at 1 and 6 months. Safety will be evaluated based on the avoidance of severe adverse events within 1 month after treatment, continuing severe pancreatic fistula at 1 month after treatment and the incidence and/or exacerbation of diabetes mellitus at 6 months after treatment. Ethics and dissemination This protocol has been approved by Okayama University Certified Review Board (approval number. CRB19-007). The results will be submitted to peer-reviewed journals and will be presented at international conferences

Diagnostic Role of 18F-Fluorodeoxyglucose Positron Emission Tomography in Gastric Mesenchymal Tumors

There have been no comparative studies investigating the results of 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in patients with gastric mesenchymal tumors, including leiomyomas, leiomyosarcomas, schwannomas, and gastrointestinal stromal tumors (GISTs). We retrospectively reviewed the data of 142 patients with pathologically diagnosed gastric mesenchymal tumors treated at 11 institutions. We analyzed the correlation between the maximum standardized uptake value (SUVmax) evaluated using fluorodeoxyglucose-positron emission tomography (FDG-PET) and the tumor size. The correlation between the SUVmax and mitotic index was also investigated in GISTs. The SUVmax (mean +/- standard deviation) was 0.5 +/- 0.6 in very low-risk GISTs (n = 42), 2.1 +/- 0.7 in low-risk GISTs (n = 26), 4.9 +/- 0.8 in intermediate-risk GISTs (n = 22), 12.3 +/- 0.8 in high-risk GISTs (n = 20), 1.0 +/- 1.0 in leiomyomas (n = 15), 6.9 +/- 1.2 in schwannomas (n = 10), and 3.5 in a leiomyosarcoma (n = 1). The SUVmax of GISTs with an undetermined risk classification was 4.2 +/- 1.3 (n = 8). Linear associations were observed between the SUVmax and tumor size in GISTs, leiomyomas, and schwannomas. The SUVmax of GISTs with a high mitotic index was significantly higher than that of GISTs with a low mitotic index (9.6 +/- 7.6 vs. 2.4 +/- 4.2). In conclusion, we observed positive correlations between the SUVmax and tumor size in GISTs, leiomyomas, and schwannomas. The SUVmax also positively correlated with the mitotic index and risk grade in GISTs. Schwannomas showed a higher FDG uptake than GISTs and leiomyomas

Circulation Characteristics and Density Wave Oscillation in a Natural Circulation Loop of Liquid Nitrogen

Circulation characteristics and flow instabilities are investigated in a natural circulation loop of liquid nitrogen. The circulation velocity increases with the increase in the heat flux and decreases with the increase in the flow restriction. Beyond a certain limit of heat flux, so called "density wave oscillation"occurs. By applying a lumped-parameter model and homogeneous two-phase flow model to the present natural circulation system, the numerical simulation is conducted. The simulation well represents the transient behavior of the system and the estimated threshold conditions of the flow oscillation agree well with the experimental results

Visualization of Bubble and Large Particle Movements in a Fluidized-Bed of Binary Mixture of Particles

Fluidized-bed combustion systems are composed of many kinds of particles with avariety of sizes,e.g.coal,sand,RDF,limestone etc.ln such a binary system of particles，the segregation,if occurs，many harm the combustion，mixing and heat transfer in the bed，depending on the particle movement. The particle movement or circulation in the fluidized-bed depends on many factors，such as the density ratio,size ratio,shape of particle，fluidization velocity. Owing to the difficulty of flow visualization，such particle movement has not been fully understood so far. This paper describes large-particle movement obtained by the flow visualization using neutron radiography. Tracer particles mixed into the fluidized particles indicated clearly bubbles and the cloud behavior around the bubble. Image processing,i.e. PIV and PTV，gives rather clear understanding on the interaction between the large particle，emulsion and/or cloud behavior in the bed

Bispectral index-guided propofol sedation during endoscopic ultrasonography

Background/Aims Bispectral index (BIS) monitors process and display electroencephalographic data are used to assess the depth of anesthesia. This study retrospectively evaluated the usefulness of BIS monitoring during endoscopic ultrasonography (EUS). Methods This study included 725 consecutive patients who underwent EUS under sedation with propofol. BIS monitoring was used in 364 patients and was not used in 361. The following parameters were evaluated: (1) median dose of propofol; (2) respiratory and circulatory depression; (3) occurrence of body movements; (4) awakening score >8 at the time; and (5) awakening score 2 hours after leaving the endoscopy room. Results The BIS group received a significantly lower median dose of propofol than the non-BIS group (159.2 mg vs. 167.5 mg; p=0.015) in all age groups. For patients aged ≥75 years, the reduction in heart rate was significantly lower in the BIS group than in the non-BIS group (1.2% vs. 9.1%; p=0.023). Moreover, the occurrence of body movements was markedly lower in the BIS group than in the non-BIS group (8.5% vs. 39.4%; p<0.001). Conclusions During EUS examination, BIS monitoring is useful for maintaining a constant depth of anesthesia, especially in patients 75 years of age or older