Search

In this paper, we prove that if d is sufficiently large square-free positive rational integer, then there is no positive definite universal quadratic O F -lattice of rank 7 where F = Q ( d ) .

The diagnosis of type 2 autoimmune pancreatitis (AIP) is dependent on typical radiologic imaging and the presence of the granulocytic epithelial lesion (GEL), which is characterized by ductal neutrophilic infiltration with or without neutrophilic acinar infiltration.We evaluated GEL and related clinicopathologic factors in 165 resected heterotopic pancreata (HPs) [57 gastric (35%), 56 duodenal (34%), 30 omental (18%), and 22 jejunal (13%)] and 29 matched orthotopic pancreata routinely examined during surgery.GEL was noted in 8% (13/165) of HPs, including ductal epithelial (6/13, 46%) and intraluminal (8/13, 62%) neutrophilic infiltrations. However, there was no GEL in orthotopic pancreata. Abdominal pain was observed in 6 (46%) patients with GEL-positive HPs. GEL was more commonly observed in HPs having symptoms (p = 0.029), a larger size (p = 0.028), and an infiltrative growth pattern (p = 0.006). In addition, periductal lymphoplasmacytic infiltration and fibrosis (both p 0.001), interstitial fibrosis (p = 0.017), acinar neutrophilic infiltration (p = 0.032), venulitis (p = 0.050), acinar ductal metaplasia (ADM; p = 0.040), and pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasms (PanIN/IPMN; p 0.001) were more commonly seen in HPs with GEL than in those without GEL. Inflammatory bowel disease was present only in one patient with GEL-negative HP.GELs are detected in a subset of HPs without clinical evidence of AIP. Therefore, for the diagnosis of AIP, GEL should be carefully interpreted with the context of other histologic, clinical, and radiologic findings.

EUS-guided transluminal drainage (EUS-TD) is increasingly used for the treatment of postoperative pancreatic fluid collections (POPFCs). A novel lumen-apposing metal stent (LAMS) was recently developed and used for the drainage of POPFCs. This study aimed to evaluate the efficacy and safety of a novel LAMS in patients with POPFCs.Forty-seven patients with symptomatic POPFCs who underwent EUS-TD with a novel LAMS (Niti-S SPAXUS; Taewoong Medical Co, Ltd, Ilsan, South Korea) between April 2019 and July 2020 were included in this study. Clinical outcomes, including technical success, clinical success, and adverse events, were retrospectively evaluated.EUS-TD was technically successful in 41 of 47 patients (87.2%). Clinical success was achieved in 37 of 41 patients (90.2%). The mean procedure time was 13.7 ± 3.5 minutes. The mean POPFC size was 59 ± 18.9 mm. The mean time interval from surgery to EUS-TD was 24.2 ± 37.6 days. Five patients experienced 6 procedural adverse events (12.8%): 4 (8.5%) POPFC infections and 2 (4.3%) distal stent migrations. The 4 patients with POPFC infection underwent additional endoscopic interventions. Of the 2 patients with stent migration, 1 underwent laparoscopic exploration and surgical extraction of the stent and 1 (2.1%) experienced POPFC recurrence, which was managed with percutaneous drainage.EUS-TD for symptomatic POPFCs with a novel LAMS is technically feasible and effective, with an acceptable adverse event rate. Further larger-scale prospective studies are required to confirm the findings of this study.

Background and Aims Endoscopic ultrasound-guided through-the-needle biopsy (EUS-TTNB) using microbiopsy forceps is performed for the accurate diagnosis of pancreatic cystic lesions (PCLs). However, there are no standardized protocols for this procedure, and the amount of data on its efficacy is limited. Here, we evaluated the feasibility, efficacy, and safety of EUS-TTNB in categorizing the types of PCLs, and identified the factors associated with diagnostic failure. Methods The prospectively collected and maintained EUS-TTNB database at Asan Medical Center was reviewed to identify patients with PCL who underwent EUS-TTNB between January 2019 and January 2021. The primary outcomes were technical success, diagnostic yield, and adverse events. Factors contributing to diagnostic failure, and the discrepancies in the diagnosis made by conventional modalities (ie, EUS-morphology, cross-sectional imaging, and cystic fluid analysis) were also evaluated. Results A total of 45 patients were analyzed. EUS-TTNB was successfully performed in all patients (technical success = 100%). Histologic diagnosis of PCL was made in 37 patients (diagnostic yield = 82%). When comparing EUS-TTNB with presumptive diagnosis, EUS-TTNB changed the diagnosis in 10 patients in terms of the categorization of the types of PCLs. The diagnostic yield was significantly higher in those who had 4 or more visible biopsy specimens per session (93%) than in those with less than 4 visible biopsy specimens per session (67%; P = .045). During follow-up, 3 (7%) patients experienced adverse events (2 acute pancreatitis, 1 intracystic bleeding), and no life-threatening adverse event occurred. Conclusions EUS-TTNB showed high technical feasibility, diagnostic yield, and good safety profile. EUS-TTNB may improve the categorization of the types of PCLs. Studies with standardized procedure protocols are needed to reduce the diagnostic failure for the types of PCLs.

Background Contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) can be used for the differential diagnosis of pancreatic lesions by evaluating microvascular circulation and patterns of contrast enhancement. However, routine use of CEH-EUS is limited by its high cost, the lack of contrast agent availability and the absence of expertise with this technique. Directional eFLOW (D-eFLOW) (Aloka Co., Ltd., Tokyo, Japan) was introduced as a new high-definition modality that detects blood flow in microvessels. Because it uses built-in functions, it entails no additional cost and reduces time for examination. The present study compared the usefulness of D-eFLOW and CEH-EUS for differential diagnosis of pancreatic and peripancreatic lesions. Methods This retrospective study analyzed 130 patients who underwent EUS and D-eFLOW examinations from January 2016 to March 2020 to evaluate pancreatic and peripancreatic masses. Results All 130 patients underwent D-eFLOW and CEH-EUS examinations. Histological diagnoses were confirmed in 130 patients by EUS-FNA and/or surgery. D-eFLOW and CEH-EUS showed good correlation in evaluating the vascularity of pancreatic and peripancreatic tumors (Fisher's exact test, p Conclusions In evaluating the characteristics of tumorous lesions, vascularity detected by D-eFLOW showed good correlation with enhancement patterns of CEH-EUS. D-eFLOW can be considered a good alternative to CEH-EUS in diagnosing pancreatic and peripancreatic masses.

Background Retroperitoneal neurogenic tumors are extremely rare pathological entities; therefore, few clinical features and natural courses, especially originating from the pancreatic/peripancreatic regions, have been reported. This study aimed to investigate the clinicopathological features of pancreatic and peripancreatic neurogenic tumors and assess the diagnostic value of computed tomography (CT) and endoscopic ultrasound-guided fine needle biopsy (EUS-FNB). Methods Between 2006 and 2018, patients who were diagnosed with neurogenic tumors were included. In total, 90 histologically confirmed cases of neurogenic tumors located in the pancreatic/peripancreatic regions were selected for analysis. Results The mean age was 49.2 ± 13.1 years. There were no differences in sex distribution of the tumors. Schwannomas (44.4%) and paragangliomas (41.1%) were the most common neurogenic tumors. The sensitivity of CT was 62.2% in 90 cases. EUS-FNB was performed in 30 cases and the sensitivity of it was 83.3%. The diagnosis of neurogenic tumors with EUS-FNB or CT was not significantly associated with tumor location and size. Surgical resection was performed in 78 cases. Of the 12 patients who did not undergo surgery, 10 cases were followed-up without any increase in tumor size. Conclusions Through the present study, we verified radiological, pathological, and clinical aspects of the pancreatic/peripancreatic neurogenic tumors which little known before, therefore, this study can serve as the basis for research to present an optimal diagnosis and treatment of neurogenic tumors. In addition, EUS-FNB is useful in the diagnosis of pancreatic/peripancreatic neurogenic tumors with relatively high sensitivity and can help establish therapeutic plans before the surgery.

Treatment strategies for small pancreatic neuroendocrine tumors (PNETs)2 cm in size are still under debate. The feasibility and safety of endoscopic ultrasound (EUS)-guided ethanol ablation (EUS-EA) have been demonstrated. However, the sample size in previous studies was small with no comparative studies on surgery. Therefore, we aimed to compare the safety and long-term outcomes of EUS-EA using ethanol with those of surgery for the management of non-functioning small PNETs.We retrospectively reviewed patients with a PNET who were managed by EUS-EA (from 2011 to 2018) and surgery (from 2000 to 2018) at Asan Medical Center. Propensity score matching (PSM) was performed to increase the comparability. The primary outcome was early and late major complications (Clavien-Dindo grade 3 or more) after treatment. The secondary outcomes were 10-year overall and disease-specific survival rates, length of hospital stay, and development of endocrine pancreatic insufficiency.A total of 97 and 188 patients were included in the EUS-EA and surgery groups, respectively. PSM created 89 matched pairs. EUS-EA was associated with a significantly lower rate of early major complications (0% vs. 11.2%; P=0.003). Late major complications occurred more frequently after surgery, with no significant difference between the groups (3.4% vs. 10.1%, P=0.07). Both treatment modalities showed comparable 10-year overall and disease-specific survival rates. The length of hospital stay was significantly shorter in the EUS-EA group (4 days vs. 14.1 days, P0.001), and endocrine pancreatic insufficiency was less common after EUS-EA than after surgery (33.3% vs. 48.6%, P=0.121).EUS-EA had fewer complications and a shorter hospital stay with similar overall and disease-specific survival rates compared to surgery, suggesting that EUS-EA may be a preferred alternative to surgical resection in selected patients with a non-functioning small PNET.

Pancreatic surgery may result in changes in pancreatic volume and endocrine function. The effects of pancreatic resection for benign neoplasms on pancreatic volume and endocrine function have not been established yet. This study aimed to investigate the long-term results of different pancreatic surgeries for benign pancreatic neoplasms on pancreatic volume and endocrine function.The medical records of 30 patients who underwent pancreaticoduodenectomy (PD) and 30 patients who underwent left-sided pancreatectomy(LP) for benign pancreatic neoplasms between 2005 and 2012 were reviewed. The changes in pancreatic volume after pancreatic surgery were assessed using multi-detector row computed tomography volumetry. Endocrine pancreatic function was evaluated on the basis of fasting glucose level or oral glucose tolerance test result.The median follow-up duration was 91.3 months (interquartile range, 75.7-119.1 months). Reduction in pancreatic volume after surgery was more pronounced in patients who underwent PD than in those who underwent LP (median percentage of volume reduction, 23.8% vs 5.1%, p .001). Multivariable analysis of prognostic factors for endocrine insufficiency showed that PD to be significant factor. (HR 3.87, 95% CI 1.12-14.66, p = .037).The surgical methods for benign pancreatic neoplasms affect the reduction in pancreatic volume. Furthermore, the methods of pancreatic surgery were associated with the risk of endocrine insufficiency. Further studies with a large number of patients are warranted to evaluate the association between the degree of volume reduction and the development of endocrine insufficiency.

Background and Aims Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) using an anti-migrating tubular self-expandable metal stent (ATSEMS) is performed in high surgical risk patients with acute cholecystitis. The newly introduced lumen-apposing metal stent (LAMS) is expected to reduce the risk of tubular self-expandable metal stent–related adverse events such as stent migration, but no comparative studies have been carried out between LAMSs and ATSEMSs for EUS-GBD. Methods We reviewed the prospectively collected EUS-GBD database at Asan Medical Center and Bucheon Soonchunhyang hospital to analyze consecutive patients with acute cholecystitis who underwent EUS-GBD with LAMSs or ATSEMSs between January 2015 and December 2017. Technical success, clinical success, adverse events, and recurrence of cholecystitis were evaluated. Results A total of 71 patients (36 with LAMSs, 35 with ATSEMSs) were analyzed. The LAMS group had longer median procedure time (15.5 minutes) than the ATSEMS group (11 minutes; P = .017). The 2 groups did not show significant differences in terms of technical success (LAMS, 94% vs ATSEMS, 100%; P = .49), clinical success (94% vs 100%; P = .49), procedure-related adverse events (0% vs 2.9%; P = .99), and stent-related late adverse events (11.8% vs 5.8%; P = .43). During follow-up, the 2 groups had similar rates of cholecystitis recurrence at 6 months (LAMS, 3.4% vs ATSEMS, 3.1%, P = .99) and 12 months (8.3% vs 3.1%, P = .56). Conclusions In high surgical risk patients with acute cholecystitis, LAMSs and ATSEMSs for EUS-GBD showed similar rates of technical success, clinical success, procedure-related adverse events, stent-related late adverse events, and recurrence of cholecystitis.

The guidelines for pancreatic intraductal papillary mucinous neoplasms (IPMNs) recommend surgical resection of all main-duct (MD) and mixed-type IPMNs in surgically fit patients. We conducted this study to identify the rates of high-grade dysplasia (HGD) and invasive carcinoma according to the morphological features of the main pancreatic duct (MPD) in patients with MD and mixed IPMN.We performed a retrospective study of 259 patients with histologically proven MD and mixed-type IPMNs who underwent surgery at six academic institutions.The rate of HGD and invasive carcinoma was 11.1% (24/216) in patients without enhancing mural nodules (MNs) and 69.8% (30/43) in patients with MNs. Multivariate analysis showed that MPD diameter of ≥10 mm [odds ratio (OR), 2.5; 95% confidence interval (CI), 1.155-5.505; P = 0.02], diffuse MPD dilatation (OR, 3.2; 95% CI, 1.152-8.998; P = 0.02), and presence of enhancing MNs in MPD (OR, 9.6; 95% CI, 3.928-23.833, P 0.0001) were significant predictors of HGD and invasive carcinoma. Of the 216 patients without enhancing MNs, 79 patients (36.6%) having both segmental MPD dilatation and MPD diameter of10 mm showed significantly lower rates of HGD and invasive carcinoma (3/79, 3.8%) than patients having both diffuse MPD dilatation and MPD diameter ≥10 mm (9/36, 25%, P = 0.001).MD and mixed-type IPMNs having segmental MPD dilatation with MPD dilation10 mm and no enhancing MNs on imaging showed a significantly lower rate of HGD and invasive carcinoma, and watchful follow-up instead of immediate surgical resection might be possible in these patients.

Endoscopic gallbladder drainage (GBD) has been performed as an alternative to percutaneous drainage for acute cholecystitis. To date, there has been no comparative study between EUS-guided cholecystostomy (EUSC) and endoscopic transpapillary cholecystostomy (ETC). The aim of this study was to compare the outcomes of EUSC and ETC.A retrospective review of an endoscopic GBD database prospectively collected at the Asan Medical Center (between July 2010 and December 2014) was performed to identify consecutive patients with acute cholecystitis who underwent attempted endoscopic GBD. Procedural and long-term outcomes were evaluated using inverse probability of treatment weighting (IPTW).A total of 172 patients (76 in the EUSC group and 96 in the ETC group) were included in this study. Seven patients who failed to undergo ETC crossed over to the EUSC group. After adjustment with the IPTW method, technical success (99.3% vs 86.6%, P .01) and clinical success (99.3% vs 86%, P .01) rates were significantly higher in the EUSC group than in the ETC group. The procedure-related adverse event rate was significantly higher in the ETC group (7.1% vs 19.3%, P = .02). The cholecystitis or cholangitis recurrence rate (12.4% vs 3.2%) was also higher in the ETC group than in the EUSC group, as identified using Cox analysis (hazard ratio, 3.01; 95% confidence interval, .73-12.9; P = .04).In patients with acute cholecystitis who are unfit for surgery, EUSC may be a more suitable treatment method than ETC.

Orbital angular momentum (OAM) mode generators have attracted considerable interest due to their unique properties and various applications in optical communication systems to improve the data transmission capacity. However, the reported OAM generators have focused on free-space-based OAM generation. In this study, we propose metasurface-based OAM generators directly deposited on the facet of a large core area photonic crystal fiber. These in-fiber OAM generators provide a very high modal purity of 99% for the OAM1 and OAM2 modes with high transmission at an operating wavelength of 1.55 µm. In addition, the proposed OAM generator provides a high purity (> 90%) over a wide wavelength bandwidth from 1.5 µm to 1.6 µm. We believe that this scheme may pave the way for in-fiber metasurface applications.

Background and Aims Although fully covered self-expandable metal stents (FCSEMSs) have been commonly used for EUS-guided biliary drainage (EUS-BD), FCSEMS migration is a main limitation of this procedure. In the present study we evaluated the technical and clinical success rates, adverse events, and long-term outcomes of a newly developed hybrid stent that has been customized for EUS-BD. Methods From September 2011 to May 2015, 54 consecutive patients with biliary obstruction were enrolled in this prospective, observational study. These patients were candidates for alternative BD techniques because of failed ERCP. The hybrid metal stent used for EUS-BD in this study was partially covered, had anchoring flaps, and is commercially available in Korea. Results EUS-guided hepaticogastrostomy (EUS-HGS) was performed in 21 patients and EUS-guided choledochoduodenostomy (EUS-CDS) in 33 patients. The technical and clinical success rates of EUS-BD were 100% (54/54) and 94.4% (51/54), respectively. Immediate adverse events developed after EUS-BD in 9 patients (16.6%; cholangitis in 3, bleeding in 2, self-limited pneumoperitoneum in 3, and abdominal pain in 1). Proximal or distal stent migration was not observed during the follow-up period (median, 148.5 days; IQR, 79.7-244), and the mean stent patency duration was 166.3 days and 329.1 days in the EUS-HGS and EUS-CDS groups, respectively. Conclusions EUS-BD with the hybrid metal stent is technically feasible and can effectively treat biliary obstruction after failed ERCP. EUS-BD with the hybrid metal stent can reduce stent-related adverse events, especially stent migration.

Background and Aims Preoperative biliary drainage (PBD) with stent placement has been commonly used for patients with malignant biliary obstruction. In PBD, the placement of fully covered self-expandable metal stents (FCSEMSs) may provide better patency duration and a lower incidence of cholangitis compared with plastic stents. We aimed to evaluate which type of stent showed better outcomes in PBD. Methods In this multicenter, prospective randomized trial, we compared PBD with FCSEMSs versus plastic stents in 86 patients with malignant biliary obstruction between January 2012 and December 2014. Patients with obstructive jaundice were randomly assigned to undergo PBD either with plastic stents or FCSEMS placement. Results Baseline characteristics were not significantly different between the 2 groups. Endoscopic stent placement was technically successful in all patients. Procedure-related adverse events were not significantly different between the 2 groups (plastic vs FCSEMS group; 16.3% vs 16.3%, P = 1.0). Reintervention was required in 16.3% of the plastic stent group and 14.0% of the FCSEMS group ( P = .763). The interval to surgery after PBD (plastic vs FCSEMS group; 14.2 ± 8.3 vs 12.3 ± 6.9 days, P = .426) was not significantly different between groups. Surgery-related adverse events occurred in 43.6% of the plastic stent group and 40.0% of the FCSEMS group ( P = .755). Conclusions In patients with resectable malignant biliary obstruction, the outcomes of PBD with plastic stents and FCSEMSs were similar. Considering the cost-effectiveness, PBD with plastic stents may be preferable to FCSEMS placement. (Clinical trial registration number: NCT01789502.)

Background and aims Acute necrotizing pancreatitis (ANP) can affect main pancreatic duct (MPD) as well as parenchyma. However, the incidence and outcomes of MPD disruption has not been well studied in the setting of ANP. Methods This retrospective study investigated 84 of 465 patients with ANP who underwent magnetic resonance cholangiopancreatography and/or endoscopic retrograde cholangiopancreatography. The MPD disruption group was subclassified into complete and partial disruption. Results MPD disruption was documented in 38% (32/84) of the ANP patients. Extensive necrosis, enlarging/refractory pancreatic fluid collections (PFCs), persistence of amylase-rich output from percutaneous drainage, and amylase-rich ascites/pleural effusion were more frequently associated with MPD disruption. Hospital stay was prolonged (mean 55 vs. 29 days) and recurrence of PFCs (41% vs. 14%) was more frequent in the MPD disruption group, although mortality did not differ between ANP patients with and without MPD disruption. Subgroup analysis between complete disruption (n = 14) and partial disruption (n = 18) revealed a more frequent association of extensive necrosis and full-thickness glandular necrosis with complete disruption. The success rate of endoscopic transpapillary pancreatic stenting across the stricture site was lower in complete disruption (20% vs. 92%). Patients with complete MPD disruption also showed a high rate of PFC recurrence (71% vs. 17%) and required surgery more often (43% vs. 6%). Conclusions MPD disruption is not uncommon in patients with ANP with clinical suspicion on ductal disruption. Associated MPD disruption may influence morbidity, but not mortality of patients with ANP. Complete MPD disruption is often treated by surgery, whereas partial MPD disruption can be managed successfully with endoscopic transpapillary stenting and/or transmural drainage. Further prospective studies are needed to study these items.

In this study, we propose a terahertz photonic crystal fiber (PCF) including double rectangular air slots in the core region based on the conventional hexagonal lattice cladding. The rectangular air slots break the geometrical symmetry, which improves birefringence compared to previously reported slot core fibers. The proposed fiber consists of the reduced number of air slots to facilitate fabrication without performance deterioration. The designed PCF provides a very high birefringence of 0.93 at 1.05 THz with a low loss of 0.05 dB/cm and supports high birefringence for a wide range of frequency bands from 0.85 to 1.3 THz. We believe that this type of fiber could be applied to various efficient short-range signal transmission applications in the terahertz region.

Background and Aims Radiofrequency ablation (RFA) has been used as a valuable treatment modality for various unresectable malignancies. EUS-guided radiofrequency ablation (EUS-RFA) of the porcine pancreas was reported to be feasible and safe in our previous study, suggesting that EUS-RFA may be applicable as an adjunct and effective alternative treatment method for unresectable pancreatic cancer. This study aimed to assess the technical feasibility and safety of EUS-RFA for unresectable pancreatic cancer. Methods An 18-gauge endoscopic RFA electrode and a radiofrequency generator were used for the procedure. The length of the exposed tip of the RFA electrode was 10 mm. After insertion of the RFA electrode into the mass, the radiofrequency generator was activated to deliver 20 to 50 W ablation power for 10 seconds. Depending on tumor size, the procedure was repeated to sufficiently cover the tumor. Results EUS-RFA was performed successfully in all 6 patients (median age 62 years, range 43-73 years). Pancreatic cancer was located in the head (n = 4) or body (n = 2) of the pancreas. The median diameter of masses was 3.8 cm (range 3cm-9cm). Four patients had stage 3 disease, and 2 patients had stage 4 disease. After the procedure, 2 patients experienced mild abdominal pain, but there were no other adverse events such as pancreatitis or bleeding. Conclusions EUS-RFA could be a technically feasible and safe option for patients with unresectable pancreatic cancer.

In this study, we propose a hexagonal photonic crystal fiber (PCF) including an elliptical Si core for high nonlinearity and birefringence, simultaneously. The propagation properties are rigorously investigated by numerical full-vector analysis. The designed fiber provides high nonlinearity and birefringence for a wide range of wavelengths, from 1.25 to 2 μm, maintaining low propagation loss by virtue of a high nonlinear coefficient and large Si refractive index. The optimal values of nonlinearity and birefringence are 2 × 105 W−1 km−1 and 0.92, respectively. In addition, the proposed hexagonal PCF can be easily fabricated with a conventional draw technique compared with other PCFs composed of complex structures to achieve high nonlinearity. It also has a high fabrication tolerance for the rotational angle of the elliptical Si core. We believe that this type of the fiber could be applied to various efficient nonlinear applications.

An orbital angular momentum (OAM) mode is a good candidate as an orthogonal basis mode set for mode division multiplexing (MDM) owing to its unique phase properties. Photonic crystal fibers support large numbers of OAM modes with notable performances. However, the effective index difference between high order OAM modes is not large enough. In this work, we propose two types of epsilon-near-zero (ENZ) materials-embedded circular photonic crystal fibers for high mode separation. Compared with previously developed photonic crystal fibers, the designed fibers exhibit a high refractive index contrast owing to the inserted ENZ materials. The designed fibers support up to 42 OAM modes. Most of these OAM modes provide a large effective index difference (Δneff > 10−3) while maintaining a radial sing mode condition over a wide wavelength range from 1.3 μm to 1.8 μm. The proposed fibers could potentially be exploited in MDM for stable transmission of OAM modes and other OAM-based applications.

Small ampullary tumors and inflammatory lesions have similar endoscopic findings and are difficult to differentiate. Narrow-band imaging (NBI) can visualize microvessels and mucosal microstructure clearly and is widely used to diagnose early gastric and colon cancer.To evaluate the usefulness of NBI for differentiating ampullary tumors from benign diseases.Retrospective cohort study.Tertiary-care hospital.All 45 patients who had suspicious ampullary lesions (enlarged or protruded morphology) during duodenoscopy and underwent NBI between March 2010 and January 2011.NBI.NBI images were assessed for irregular villous arrangement, irregular villous size, ridge disappearance, demarcation with normal villi, and abnormal microvasculature. Histology of NBI-guided lesion biopsy specimens provided the final diagnoses. Agreement between NBI images and histologic findings was analyzed.Of the 60 ampullary lesions, 11, 26, and 23 were adenocarcinomas, adenomas, and benign inflammatory diseases, respectively. Irregular villous arrangement, irregular villous size, ridge disappearance, demarcation with normal villi, and abnormal microvasculature were observed in 45%, 63%, 50%, 48%, and 58% of the lesions, respectively. Multivariate analysis revealed that irregular villous arrangement (odds ratio [OR] 15.76; 95% confidence interval [CI], 3.38-64.12; P .001) and abnormal microvasculature (OR 86.63; 95% CI, 14.56-515.41; P .001) were significant independent factors for identifying ampullary adenomas and adenocarcinoma. All tumors had at least one abnormal NBI feature.Retrospective design.The NBI findings of irregular villous arrangement and/or abnormal microvasculature were useful for differentially diagnosing ampullary tumors. NBI may complement the accurate diagnosis of ampullary lesions by white-light imaging.

Background/Objectives Prediction of malignancy in patients with BD-IPMNs is critical for the management. The aim of this study was to elucidate predictors of malignancy in patients with ‘pure' BD-IPMNs who had a main pancreatic duct (MPD) diameter of ≤5 mm according to the most recent international consensus criteria and in whom MPD involvement was excluded on postoperative histology. Methods We identified 177 patients with ‘pure' BD-IPMNs based on preoperative imaging and postoperative histology from 15 tertiary referral centers in Korea. BD-IPMNs with low-grade ( n = 72) and moderate-grade ( n = 66) dysplasia were grouped as benign and BD-IPMNs with high-grade dysplasia ( n = 10) and invasive carcinoma ( n = 29) were grouped as malignancy. Results On univariate analysis, particular symptoms (jaundice and clinical pancreatitis), CT findings (cyst size > 3 cm, the presence of enhancing mural nodules) and EUS features (the presence of mural nodules, the mural nodule size > 5 mm) were significant risk factors predicting malignant BD-IPMNs. Multivariate analysis revealed that the cyst size > 3 cm (odds ratio = 9.9), the presence of enhancing mural nodules on CT (odds ratio = 19.3) and the mural nodule size > 5 mm on EUS (odds ratio = 14.9) were the independent risk factors for the presence of malignancy in BD-IPMNs ( p Conclusions The cyst size > 3 cm, the presence of enhancing mural nodules on CT, the mural nodule size > 5 mm on EUS are three independent predictors of malignancy in patients with ‘pure' BD-IPMNs.

In 1911, Dubouis determined all positive integers that are represented by a sum of k positive squares for any k ≥ 4 . In this article, we generalize Dubouis' result to the binary case. We determine all binary forms that are represented by a sum of k nonzero squares for any k ≥ 5 .

Background EUS-guided and percutaneous lavage therapy for large hepatic cysts can replace surgical drainage. EUS-guided therapy can especially enable the alcohol lavage to be done with a 1-step approach. Objective To evaluate the utility of EUS-guidance and percutaneous ethanol lavage therapy. Design Retrospective cohort study. Setting Tertiary-care referral teaching hospital. Patients Adult patients with large liver cysts who underwent cyst drainage and alcohol ablation between 2009 and 2012. Interventions Ethanol lavage via percutaneous and/or EUS-guided approaches. Main Outcome Measurements Feasibility, efficacy, and safety of ethanol lavage. Results Seventeen patients with 19 hepatic cysts were enrolled. The median cyst volume before therapy was 368.9 mL (interquartile range, 195.3-795.9 mL). Ten cysts were drained by the percutaneous approach with a pigtail catheter, and 8 cysts underwent EUS-guided aspiration and lavage treatment. In 1 case, both the percutaneous approach and EUS-guided puncture were used. During the median 11.5-month follow-up of the percutaneous approach group, the cysts showed 97.5% reduction. During the median 15-month follow-up of the EUS-guided group, the cysts showed nearly 100% reduction. Percutaneous catheter drainage ethanol lavage was more feasible for right-sided larger cysts, whereas the EUS-guided approach was useful for left-sided lobe cysts. Limitations Single-center retrospective study. Conclusion Excellent symptomatic and radiologic responses and long-term results were achieved with percutaneous catheter–guided and EUS-guided ethanol lavage. Ethanol lavage could be considered a primary method of treatment for hepatic cysts given its high degree of technical feasibility and safety.

This review addresses the role of endoscopy in the diagnosis and treatment of autoimmune pancreatitis (AIP) and provides a diagnostic process for patients with suspected AIP. When should AIP be suspected? When can it be diagnosed without endoscopic examination? Which endoscopic approaches are appropriate in suspected AIP, and when? What are the roles of diagnostic endoscopic retrograde pancreatography, endoscopic biopsies, and IgG4 immunostaining? What is the proper use of the steroid trial in the diagnosis of AIP in patients with indeterminate computed tomography imaging? Should biliary stenting be performed in patients with AIP with obstructive jaundice?

There are two distinct subtypes of autoimmune pancreatitis (AIP): type 1 and type 2. Type 1 AIP is the pancreatic manifestation of systemic fibroinflammatory disease, which is named as IgG4-related disease. On the other hand, type 2 AIP is a pancreatic disorder that is not associated with IgG4. Type 1 and type 2 AIP have different clinical profiles and histologic findings. We present a 22-year-old man who has been diagnosed as type 1 AIP with histologically proven granulocytic epithelial lesion after surgical resection for pancreatic head mass. Since the patient had no pancreatic duct narrowing, elevation of serum IgG4, and other organ involvement, it was very difficult to diagnose preoperatively. This is a rare and interesting case in which histologic features of type 1 and type 2 AIP coexist.

Background The differential diagnosis between benign and malignant polyps of the gallbladder (GB) is often challenging. Objectives To evaluate whether contrast-enhanced harmonic EUS (CEH-EUS) might be an accurate method for discriminating malignant GB polyps from benign polyps. Design Observational study. Setting Tertiary care medical center. Patients Ninety-three patients with GB polyps larger than 10 mm in diameter that were detected by conventional EUS underwent CEH-EUS for evaluation of microvasculature. Intervention CEH-EUS was performed using a radial echoendoscope and the extended pure harmonic detection mode. Main Outcome Measurements The abilities of conventional EUS and CEH-EUS to diagnose malignant polyp were compared. Two blinded reviewers classified the perfusion images into 3 categories: diffuse enhancement, perfusion defect, or nonenhancement. The vessel images were categorized as having a regular spotty vessel, an irregular vessel, or no vessels. Results An irregular vessel pattern determined by CEH-EUS aided in the diagnosis of malignant polyps with a sensitivity and specificity of 90.3% and 96.6%, respectively. The presence of perfusion defects, determined by CEH-EUS, was calculated to diagnose malignant polyps with a sensitivity and specificity of 90.3% and 94.9%, respectively. Based on the definitely determined diagnosis, sensitivity and specificity for CEH-EUS were 93.5% and 93.2% versus 90.0% and 91.1% for conventional EUS. In 8 cases, management changed after CEH-EUS. Limitations A tertiary medical center with a limited number of patients. Conclusions The presence of irregular intratumoral vessels or perfusion defects seen on CEH-EUS may be sensitive and accurate predictors of malignant GB polyps. CEH-EUS offers slightly improved diagnostic accuracy compared with EUS.

Percutaneous transhepatic gallbladder drainage (PTGBD) is a less invasive standard procedure to decompress the inflamed gallbladder in patients who are at high risk for emergency cholecystectomy. Recently, endoscopic ultrasonography-guided transmural gallbladder drainage (EUS-GBD) has been proposed as an alternative effective treatment modality for the management of acute cholecystitis in high-risk patients. EUS-GBD includes EUS-guided nasogallbladder drainage, gallbladder aspiration, and gallbladder stenting via a transmural endoscopic approach. Several investigators have reported high technical success with acceptable complication rates. Further prospective evaluation of the feasibility, safety, and efficacy of EUS-GBD will help identify the most suitable indications for this procedure. This article is a detailed review of the use of EUS for gallbladder drainage, with an emphasis on its technical aspects.

Background EUS-guided radiofrequency ablation (EUS-RFA) could be used as an adjunct and effective alternative mode of treatment for unresectable locally advanced and nonmetastatic pancreatic adenocarcinoma. However, its translation into clinical practice has been restricted because of limited data and high procedure-related risk. Objective To evaluate the feasibility, efficacy, and safety of EUS-RFA in the normal porcine pancreas. Design Prospective, endoscopic, experimental study in a porcine model. Setting Tertiary-care referral center animal laboratory. Patients Animal study. Intervention EUS-RFA of the pancreas was attempted on 10 adult mini pigs. An 18-gauge endoscopic RFA electrode was used to puncture the body and tail of the pancreas, with an output power of 50 W for 5 minutes. Main Outcome Measurements The feasibility, efficacy, and safety of EUS-RFA. Results A spherical necrotic lesion surrounded by fibrous tissue localized in the pancreatic parenchyma was observed on histopathologic examination. The mean diameter of the ablated tissue was 23.0 ± 6.9 mm. No major procedure-related complications were noted, and all pigs survived without any distress behavioral pattern for 7 days until autopsy. Limitations Small sample size with short-term observation and the lack of evaluation of the head of the pancreas. Conclusion EUS-RFA of the pancreatic body and tail was feasible, effective, and relatively safe in a porcine model. More animal studies to assess damage to adjacent organs are required before human trials can be conducted.

Background To determine the safety and efficacy of neoadjuvant gemcitabine/capecitabine followed by surgery for the treatment of locally advanced pancreatic adenocarcinoma (LAPC). Methods Patients with histologically confirmed LAPC were given 3–6 cycles of fixed-dose rate gemcitabine/capecitabine every 3 weeks. At the end of chemotherapy, patients were restaged and underwent surgery if the disease was not classified as unresectable. Our institutional criteria were used to classify respectability, which was recategorized on the basis of National Comprehensive Cancer Network (NCCN) criteria retroactively. The primary end point was rate of microscopic curative resection. Results Forty-three eligible patients (18 with borderline resectable disease and 25 with unresectable disease on the basis of NCCN criteria) were enrolled. The radiologic response rate was 18.6%. Grade three or worse adverse events were mainly hand–foot syndrome (11%), and there were no grade four adverse events. Surgery was performed in 17 patients (39.5%); pathologic curative resection (R0) was achieved in 14 patients (32.5%) among total 43 patients, and 82.3% (14/17) among the 17 resected patients. With 43-month follow-up, the median overall was 16.6 months with a median progression-free survival of 10.0 months. Median overall survival was 23.1 months in patients who underwent surgery and 13.2 months in patients who could not complete the surgery (P = .017). Conclusion A subset of patients with borderline or unresectable pancreatic cancer could be performed curative tumor resection after neoadjuvant chemotherapy. Some patients might be benefit on survival from neoadjuvant chemotherapy after surgical resection.

Hybrid 1D nanostructured Au/ZnO arrays were created by heat treatment of a spin-coated zinc acetate-PVA-Au(III) layer on surface relief grating and functioned as an electrochemical and optical D(+)-glucose sensor due to electrochemical oxidation between hybrid nanostructures and D(+)-glucose. The morphology and chemical composition of 1D Au/ZnO hybrid arrays were characterized by means of AFM, SEM, EDAX, and XPS. Electrochemical and optical sensitivities by the addition of D(+)-glucoses on 1D Au/ZnO arrays were investigated using Cyclic voltammetry and UV–vis-NIR spectra in the medical concentration ranges of 0.5, 2.0, and 8.0 mM.

Background & Aims Endoscopic ultrasound-guided transmural gallbladder drainage (EUS-GBD) is an alternative to percutaneous transhepatic gallbladder drainage (PTGBD) for patients with acute, high-risk, or advanced-stage cholecystitis who do not respond to initial medical treatment and cannot undergo emergency cholecystectomy. However, the technical feasibility, efficacy, and safety of EUS-GBD and PTGBD have not been compared. Methods Fifty-nine patients with acute cholecystitis, who did not respond to initial medical treatment and were unsuitable for an emergency cholecystectomy, were chosen randomly to undergo EUS-GBD (n = 30) or PTGBD (n = 29). The technical feasibility, efficacy, and safety of EUS-GBD and PTGBD were compared. Results EUS-GBD and PTGBD showed similar technical (97% [29 of 30] vs 97% [28 of 29]; 95% 1-sided confidence interval lower limit, −7%; P = .001 for noninferiority margin of 15%) and clinical (100% [29 of 29] vs 96% [27 of 28]; 95% 1-sided confidence interval lower limit, −2%; P = .0001 for noninferiority margin of 15%) success rates, and similar rates of complications (7% [2 of 30] vs 3% [1 of 29]; P = .492 in the Fisher exact test) and conversions to open cholecystectomy (9% [2 of 23] vs 12% [3 of 26]; P = .999 in the Fisher exact test). The median post-procedure pain score was significantly lower after EUS-GBD than after PTGBD (1 vs 5; P Conclusions EUS-GBD is comparable with PTGBD in terms of the technical feasibility and efficacy; there were no statistical differences in the safety. EUS-GBD is a good alternative for high-risk patients with acute cholecystitis who cannot undergo an emergency cholecystectomy.

Background Although early laparoscopic cholecystectomy is the treatment of choice for patients with acute cholecystitis, percutaneous cholecystostomy has been performed in patients unsuitable for cholecystectomy. EUS-guided transgastric/transduodenal gallbladder drainage by using a plastic stent and/or nasobiliary drainage may be an alternative effective treatment for these patients, but bile leakage into the peritoneal space causing bile peritonitis is not uncommon during placement of a plastic stent. Objective To evaluate the technical feasibility and safety of EUS-guided transgastric/transduodenal gallbladder drainage with single-step placement of a modified covered self-expandable metal stent (CSEMS) in patients with acute cholecystitis who are unsuitable for cholecystectomy. Design Prospective feasibility study. Setting Tertiary-care referral center. Patients This study involved 15 patients with acute cholecystitis who did not respond to initial medical treatment and were unsuitable for cholecystectomy. Intervention EUS-guided transgastric/transduodenal gallbladder drainage with single-step placement of a modified CSEMS. Main Outcome Measurements Technical success, functional success, complications associated with the placement of a metal stent, and recurrence of acute cholecystitis. Results Modified CSEMSs were successfully placed in all patients through the stomach (n = 10) or duodenum (n = 5). All patients achieved functional success within 3 days of metal stent placement. Pneumoperitoneum occurred in two patients during or after the procedure, but both patients improved with conservative management. During follow-up (median 145 days, range 60-297 days), no patient experienced recurrent cholecystitis. Limitations Small patient population without long-term follow-up. Conclusion Placement of a modified CSEMS after EUS-guided transgastric/transduodenal gallbladder drainage may be a feasible and safe alternative to treatments such as percutaneous cholecystostomy in patients with acute cholecystitis who are unsuitable for cholecystectomy.

Background & Aims Endoscopic ultrasonography (EUS)-guided interventions have been used to treat patients with cystic lesions of the pancreas (CLPs). We used EUS to guide injection and lavage of ethanol, followed by injection of paclitaxel, into cysts, and investigated treatment response and predictors. Methods Fifty-two patients were enrolled in the study using the following inclusion criteria: unilocular or oligolocular cysts, indeterminate cystic lesions that required EUS fine-needle aspiration, and cystic lesions that grew during the observation period. Forty-seven patients were followed up for more than 12 months and their outcomes were analyzed. Results The mean diameter of the CLPs was 31.8 mm (range, 17–68 mm) and the estimated volume was 14.09 mL (range, 1.16–68.74 mL). Twenty CLPs were oligolocular. The mean level of carcinoembryonic antigen was 463 ng/mL (range, 1–8190 ng/mL). The median follow-up period was 21.7 months. A complete response was observed in 29 patients, a partial response in 6 patients, and persistent cysts in 12 patients. Four of 12 patients with persistent cysts underwent surgery. The histopathologic degree of epithelial ablation varied from 0% to 100%. Based on univariate analysis, EUS diameter and original volume predicted cyst resolution; in multivariate analysis, only original volume predicted resolution. Mild pancreatitis and splenic vein obliteration each occurred in 1 patient. Conclusions EUS-guided injection and lavage of ethanol, followed by injection of paclitaxel, appears to be a safe method for treating pancreatic cysts; 62% of patients had complete resolution. Small cyst volume predicted complete resolution.

Background Recently, placement of fully covered self-expandable metal stents (FCSEMSs) has been proposed as an alternative treatment for the management of benign biliary strictures. However, the major limitations of FCSEMSs are frequent migration and removal complications. Objective We conducted this study to compare the antimigration effects, complication rates, and short-term efficacy of 2 FCSEMSs with either an anchoring flap (AF) or a flared end (FE) at the proximal end of the stent. Design A multicenter, prospective comparative pilot study. Setting Two tertiary referral centers. Patients A total of 43 patients with benign biliary stricture who were candidates for placement of FCSEMSs were assigned to the AF (n = 22) or the FE group (n = 21). Interventions Predefined duration of placement and removal of FCSEMSs. Results After a median period of placement of 6 months (interquartile range 4-6), no patients in the AF group and 33% of patients (7 of 21, 1 in proximal and 6 in distal) in the FE group had stent migration ( P = .004). The removal rate of the FCSEMSs was 100% in both groups (per protocol, n=22 in the AF group and n=17 in the FE group). Immediate improvement of biliary stricture was 91% (20/22, per protocol) in the AF group and 88% (15/17, per protocol) in the FE group. All stents were removed without difficulty. Limitations Short-term follow-up after the removal of FCSEMSs. Conclusions With regard to the antimigration effect of FCSEMSs for benign biliary stricture, the AF design may be superior to the FE. For up to 6 months, both FCSEMSs can be endoscopically removed without complications. (Clinical trial registration number: NCT00945516.)

In this article, we present the numerical simulations of a real cylinder head quench cooling process employing a newly developed boiling phase change model using the commercial CFD code AVL-FIRE v8.5. Separate computational domains constructed for the solid and liquid regions are numerically coupled at the interface of the solid–liquid boundaries using the AVL-Code-Coupling-Interface (ACCI) feature. The boiling phase change process triggered by the dipping hot metal and the ensuing two-phase flow is handled using an Eulerian two-fluid method. Multitude of flow features such as vapor pocket generation, bubble clustering and their disposition, are captured very effectively during the computation, in addition to the variation of the temperature pattern within the solid region. A comparison of the registered temperature readings at different monitoring locations with the numerical results generates an overall very good agreement and indicates the presence of intense non-uniformity in the temperature distribution within the solid. Overall, the predictive capability of the new boiling model is well demonstrated for real-time quenching applications.