Compact lithium niobate plasmonic modulator.

Lithium niobate (LN)-based modulators offer superior modulation performances, including high-speed modulation, linearity, and temperature stability. However, these devices exhibit larger sizes due to the low light-matter interaction despite a significant electro-optic coefficient. In this work, we present a compact LN-based modulator using a plasmonic mode that confines the optical mode in a very narrow gap. By filling the gap with LN, the confinement factor in the LN is significantly enhanced. The proposed modulator provides an extremely small half-wave voltage-length product, VπL of 0.02 V/cm at an optical communication wavelength (λ = 1.55 µm). The proposed modulator scheme can be utilized in a wide range of optical communication devices that demand small footprints and a high-speed operation.

Enhancing Mural Nodules in the Main Pancreatic Duct of Main and Mixed Types of Intraductal Papillary Mucinous Neoplasms: Does Size Matter in Malignancy Risk?

Background/Aims: Most guidelines recommend surgical resection of all main duct (MD) and mixed-type (MT) intraductal papillary mucinous neoplasms (IPMNs) in suitable patients. However, there is little evidence regarding the malignancy risk of enhancing mural nodules (EMNs) that are present only in the main pancreatic duct (MPD) in patients with MD- and MT-IPMNs. Therefore, this study aimed to identify the clinical and morphological features associated with malignancy in MD- and MT-IPMNs with EMNs only in the MPD. Methods: We retrospectively enrolled 50 patients with MD- and MT-IPMNs with EMNs only in the MPD on contrast-enhanced magnetic resonance imaging. We evaluated the clinical characteristics and preoperative radiologic imaging results of MPD morphology and EMN size and analyzed the risk factors associated with malignancy. Results: Histological findings of EMNs were low-grade dysplasia (38%), malignant lesions (62%), high-grade dysplasia (34%), and invasive carcinoma (28%). On the receiver operating characteristic curve, the cutoff value of EMN size on magnetic resonance imaging for best predicting malignancy was 5 mm (sensitivity, 93.5%; specificity, 52.6%; area under the curve, 0.753). Multivariate analysis showed that only EMN >5 mm (odds ratio, 27.69; confidence interval, 2.75 to 278.73; p=0.050) was an independent risk factor for malignancy. Conclusions: EMNs of >5 mm are associated with malignancy in patients with MD- and MT-IPMNs with EMNs that are present only in the MPD, in accordance with the international consensus guidelines.

Highly efficient graphene terahertz modulator with tunable electromagnetically induced transparency-like transmission.

Graphene-based optical modulators have been extensively studied owing to the high mobility and tunable permittivity of graphene. However, weak graphene-light interactions make it difficult to achieve a high modulation depth with low energy consumption. Here, we propose a high-performance graphene-based optical modulator consisting of a photonic crystal structure and a waveguide with graphene that exhibits an electromagnetically-induced-transparency-like (EIT-like) transmission spectrum at terahertz frequency. The high quality-factor guiding mode to generate the EIT-like transmission enhances light-graphene interaction, and the designed modulator achieves a high modulation depth of 98% with a significantly small Fermi level shift of 0.05 eV. The proposed scheme can be utilized in active optical devices that require low power consumption.

Comparison of the long-term outcomes between proximal and distal IgG4-related sclerosing cholangitis: A multicenter cohort study.

BACKGROUND AND AIMS: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is considered a biliary manifestation of IgG4-related diseases. However, there has been a controversy on the clinical outcomes according to the location of the involved bile duct. We therefore compared the clinical outcomes and long-term prognosis of IgG4-SC with proximal bile duct involvement (proximal IgG4-SC) and IgG4-SC with distal bile duct involvement (distal IgG4-SC). METHODS: We reviewed the data of patients with IgG4-SC that were prospectively collected at 10 tertiary centers between March 2002 and October 2020. Clinical manifestations, outcomes, association with autoimmune pancreatitis (AIP), steroid-responsiveness, and relapse of IgG4-SC were evaluated. RESULTS: A total of 148 patients (proximal IgG4-SC, n = 59; distal IgG4-SC, n = 89) were analyzed. The median age was 65 years (IQR, 56.25-71), and 86% were male. The two groups were similar in terms of jaundice at initial presentation (51% vs 65%; P = 0.082) and presence of elevated serum IgG4 (66% vs 70%; P = 0.649). The two groups showed significant differences in terms of steroid-responsiveness (91% vs 100%; P = 0.008), association with AIP (75% vs 99%; P = 0.001), and occurrence of liver cirrhosis (9% vs 1%; P = 0.034). During a median follow-up of 64 months (IQR, 21.9-84.7), the cumulative relapse-free survival was significantly different between the two groups (67% vs 79% at 5 years; P = 0.035). CONCLUSIONS: Relapse of IgG4-SC frequently occurred during follow-up. Proximal IgG4-SC and distal IgG4-SC had different long-term outcomes in terms of steroid-responsiveness, occurrence of liver cirrhosis, and recurrence. It may be advantageous to determine the therapeutic and follow-up strategies according to the location of bile duct involvement.

Comparison of EUS-guided ablation and surgical resection for nonfunctioning small pancreatic neuroendocrine tumors: a propensity score-matching study.

BACKGROUND AND AIMS: Treatment strategies for small pancreatic neuroendocrine tumors (PNETs) <2 cm in size are still under debate. The feasibility and safety of EUS-guided ethanol ablation (EUS-EA) have been demonstrated. However, sample sizes in previous studies were small with no comparative studies on surgery. Therefore, we aimed to compare the safety and long-term outcomes of EUS-EA with those of surgery for the management of nonfunctioning small PNETs. METHODS: We retrospectively reviewed patients with PNETs 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 comparability. The primary outcome was early and late major adverse events (Clavien-Dindo grade ≥III) after treatment. Secondary outcomes were 10-year overall (OS) and disease-specific survival (DSS) rates, length of hospital stay, and development of endocrine pancreatic insufficiency. RESULTS: Of all patients, 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 adverse events (0% vs 11.2%, P = .003). Late major adverse events occurred more frequently after surgery, with no significant difference between groups (3.4% vs 10.1%, P = .07). Both treatment modalities showed comparable 10-year OS and DSS rates. The length of hospital stay was significantly shorter in the EUS-EA group (4 days vs 14.1 days, P < .001), and endocrine pancreatic insufficiency was less common after EUS-EA than after surgery (33.3% vs 48.6%, P = .121). CONCLUSIONS: EUS-EA had fewer adverse events and a shorter hospital stay with similar OS and DSS rates compared with surgery, suggesting that EUS-EA may be a preferred alternative to surgical resection in selected patients with nonfunctioning small PNETs.

Long-term Outcomes of Endoscopic Intraductal Radiofrequency Ablation for Ampullary Adenoma with Intraductal Extension after Endoscopic Snare Papillectomy.

Background/Aims: There are limitations in treating ampullary adenomas with intraductal extension using conventional endoscopic modalities. Endoscopic intraductal radiofrequency ablation (ID-RFA) may be useful for treating intraductal (common bile duct [CBD] and/or pancreatic duct [PD]) extensions of ampullary adenomas, but long-term data are lacking. We thus evaluated the long-term outcomes of endoscopic ID-RFA for managing ampullary adenomas with intraductal extension. Methods: Prospectively collected endoscopic ID-RFA database at Asan Medical Center was reviewed to identify consecutive patients with ampullary adenoma who underwent ID-RFA for intraductal extension between January 2018 and August 2021. Technical success, short-term and long-term clinical success, and adverse events were evaluated. Results: A total of 29 patients (14 CBD, 1 PD, and 14 CBD and PD) were analyzed. All patients had undergone endoscopic snare papillectomy prior to ID-RFA. A median of one session of ID-RFA (range, 1 to 3) for residual or relapsed intraductal extension of ampullary adenoma were successfully performed (technical success=100%). Both biliary and pancreatic stenting were routinely performed after ID-RFA to prevent ductal stricture. After a median follow-up of 776 days (interquartile range, 470 to 984 days), the short-term and long-term clinical success rates were 93% and 76%, respectively. Seven patients experienced procedural adverse events and three patients developed ductal strictures. Conclusions: Endoscopic ID-RFA showed good long-term outcomes in treating residual or relapsed ampullary adenomas with intraductal extension. Repeated ID-RFA may be considered as an option for managing recurrence. Further studies are needed to standardize the procedure.

Long-term outcomes of endoscopic ultrasound-guided gallbladder drainage versus in situ or ex situ percutaneous gallbladder drainage in real-world practice.

OBJECTIVES: Many studies showed better outcomes of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) when compared with percutaneous transhepatic gallbladder drainage (P-GBD) in which most tubes were left in situ. However, no studies have directly compared EUS-GBD with P-GBD after tube removal (ex situ). We compared the long-term outcomes of EUS-GBD and ex situ or in situ P-GBD in high surgical risk patients with acute cholecystitis. METHODS: We reviewed the records of 182 patients (EUS-GBD, n = 75; P-GBD, n = 107) who underwent gallbladder drainage. The procedural outcomes, long-term outcomes, and adverse events were compared. RESULTS: The EUS-GBD group and the P-GBD group had similar rates of technical and clinical success. Early adverse events were less common in the EUS-GBD group (5.5% vs. 18.9%, P = 0.010). The long-term outcomes were evaluated in 168 patients (EUS-GBD, n = 67; P-GBD ex situ, n = 84; P-GBD in situ, n = 17). The rate of cholecystitis recurrence in the EUS-GBD group (6.0%) was similar to that in the P-GBD ex situ group (9.6%, P = 0.422), but significantly lower than that in the P-GBD in situ group (23.5%, P = 0.049). P-GBD in situ was a significant predictor of recurrent cholecystitis (hazard ratio 14.6; 95% confidence interval 2.9-72.8). CONCLUSION: The long-term recurrence rate of acute cholecystitis in patients who underwent EUS-GBD was comparable to that in patients whose P-GBD could be removed. However, patients in whom P-GBD could not be removed showed higher rates of recurrent cholecystitis than patients with EUS-GBD.

Graphene-based fine tuning of Fano resonance transmission of quasi-bound states in the continuum.

Quasi-bound state in the continuum (BIC) has significant potential because it supports an ultra-high quality factor (Q-factor). Here, we propose a graphene-embedded subwavelength grating that supports quasi-BIC for tuning very sharp Fano resonance transmission. The strongly enhanced light-graphene interaction from the quasi-BIC enables fine variation of the transmission at the resonant wavelength. The Q-factor of quasi-BIC significantly decreases as the Fermi level of graphene increases. We also propose a low-energy consumption THz-wave modulator using this scheme. The designed modulator shows approximately 100% modulation depth with a Fermi level shift of only EF = 90 meV.

Autoimmune Pancreatitis and Immunoglobulin G4-related Sclerosing Cholangitis: Past, Present, and Future.

The emergence of glucocorticoid-responsive autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC), a new disease entity, has attracted considerable interest within the international gastroenterology community. The typical manifestations of AIP/IgG4-SC are obstructive jaundice and pancreatic enlargement in the elderly, which may mimic the presentations of pancreatobiliary malignancies. The timely diagnosis of AIP/IgG4-SC can lead to adequate glucocorticoid treatment, whereas a misdiagnosis can result in unnecessary major surgery. The diagnostic criteria used to diagnose AIP include several cardinal features of AIP that can be detected via pancreatic parenchymal imaging, ductal imaging, serum IgG4 levels, histopathology, other organ involvement, and response to glucocorticoid therapy. The differential diagnosis of AIP/IgG4-SC may include pancreatobiliary malignancies and primary sclerosing cholangitis. Although most patients with AIP/IgG4-SC respond well to glucocorticoid therapy, there is a frequent relapse of the disease in the long term. This review describes the evolution of the concept of AIP and IgG4-related disease, including the development of diagnostic criteria, discusses the current practice for diagnosis and treatment, and suggests prospects for research.

The usefulness of endobiliary radiofrequency ablation before metal stent placement in unresectable malignant hilar obstruction.

BACKGROUND AND AIM: EB-RFA with self-expandable metal stent (SEMS) may improve the stent patency and patient survival in malignant extrahepatic biliary obstruction. However, there are few studies on the role of EB-RFA for malignant hilar obstruction (MHO). This study aimed to assess the feasibility, efficacy, and safety of EB-RFA for MHO. METHODS: We retrospectively compared the stent patency and survival among 79 consecutive patients with MHO who underwent bilateral uncovered SEMS placement without and with EB-RFA between April 2016 and January 2020. RESULTS: Fifty-one patients (64.6%) underwent SEMS placement alone (stent alone group), whereas 28 (35.4%) underwent SEMS placement after EB-RFA (RFA-stent group). All procedures were successful (100%). During follow-up, stent occlusion occurred in 59 patients (74.7%), of which 40 (78.4%) and 19 (67.9%) were in the stent alone and RFA-stent groups, respectively. There was no difference in stent patency (192 ± 39.2 days vs 140 ± 53.7 days, P = 0.41) and survival (311 ± 24.7 days vs 311 ± 46.9 days, P = 0.73) between the stent alone and RFA-stent groups. Multivariate cox analysis showed a hazard ratio (HR) of 2.892 (1.579-5.294, P = 0.001) for stent occlusion in patients who did not receive chemotherapy. EB-RFA had no significant effect on stent occlusion (HR, 1.150, 0.644-2.053, P = 0.636). CONCLUSIONS: SEMS placement after EB-RFA in MHO was not associated with improvement in the stent patency or patient survival. Further prospective randomized studies are necessary to establish the effectiveness of EB-RFA with stents in MHO.

Systematic review and meta-analysis of MRI features for differentiating autoimmune pancreatitis from pancreatic adenocarcinoma.

OBJECTIVES: To identify reliable MRI features for differentiating autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC) and to summarize their diagnostic accuracy. METHODS: We conducted a systematic literature review and meta-analysis using PubMed, EMBASE, and the Cochrane Library to identify original articles published between January 2006 and July 2021. The pooled diagnostic accuracy, including the diagnostic odds ratios (DORs) with 95% confidence intervals (CIs) of the identified features, was calculated using a bivariate random effects model. RESULTS: Twelve studies were included, and 92 overlapping descriptors were subsumed under 16 MRI features. Ten features favoring AIP were diffuse enlargement (DOR, 75; 95% CI, 9-594), capsule-like rim (DOR, 52; 95% CI, 20-131), multiple main pancreatic duct (MPD) strictures (DOR, 47; 95% CI, 17-129), homogeneous delayed enhancement (DOR, 46; 95% CI, 21-104), low apparent diffusion coefficient value (DOR, 30), speckled enhancement (DOR, 30), multiple pancreatic masses (DOR, 29), tapered narrowing of MPD (DOR, 15), penetrating duct sign (DOR, 14), and delayed enhancement (DOR, 13). Six features favoring PDAC were target type enhancement (DOR, 41; 95% CI, 11-158), discrete pancreatic mass (DOR, 35; 95% CI, 15-80), upstream MPD dilatation (DOR, 13), peripancreatic fat infiltration (DOR, 10), upstream parenchymal atrophy (DOR, 5), and vascular involvement (DOR, 3). CONCLUSION: This study identified 16 informative MRI features to differentiate AIP from PDAC. Among them, diffuse enlargement, capsule-like rim, multiple MPD strictures, and homogeneous delayed enhancement favored AIP with the highest DORs, whereas discrete mass and target type enhancement favored PDAC. KEY POINTS: • The MRI features with the highest pooled diagnostic odds ratios (DORs) for autoimmune pancreatitis were diffuse enlargement of the pancreas (75), capsule-like rim (52), multiple strictures of the main pancreatic duct (47), and homogeneous delayed enhancement (46). • The MRI features with the highest pooled DORs for pancreatic ductal adenocarcinoma were target type enhancement (41) and discrete pancreatic mass (35).

Stereotactic Body Radiation Therapy versus Concurrent Chemoradiotherapy for Locally Advanced Pancreatic Cancer: A Propensity Score-Matched Analysis.

In locally advanced pancreatic cancer (LAPC), stereotactic body radiation therapy (SBRT) has been applied as an alternative to concurrent chemoradiotherapy (CCRT); however, direct comparative evidence between these two modalities is scarce. The aim of this study was to compare the clinical outcomes of SBRT with CCRT for LAPC. We retrospectively reviewed the medical records of patients with LAPC who received SBRT (n = 95) or CCRT (n = 66) with a concurrent 5-FU-based regimen between January 2008 and July 2016. The clinical outcomes of freedom from local progression (FFLP), progression-free survival (PFS), overall survival (OS), and toxicities were analyzed before and after propensity score (PS) matching. After a median follow-up duration of 15.5 months (range, 2.3-64.5), the median OS, PFS, and FFLP of the unmatched patients were 17.3 months, 11 months, and 19.6 months, respectively. After PS matching, there were no significant differences between the SBRT and CCRT groups in terms of the 1-year rates of OS (66.7% vs. 80%, p = 0.455), PFS (40.0% vs. 54.2%, p = 0.123), and FFLP (77.2% and 87.1%, p = 0.691). Our results suggest SBRT could be a feasible alternative to CCRT in treating patients with LAPC.

Granulocytic epithelial lesion (GEL) in heterotopic pancreas.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Effect of prophylactic endoscopic clipping for prevention of delayed bleeding after endoscopic papillectomy for ampullary neoplasm: a multicenter randomized trial.

BACKGROUND : Endoscopic clip placement is technically challenging using a duodenoscope, limiting their application for treatment of bleeding after endoscopic papillectomy. This study evaluated the efficacy of newly designed clips to prevent bleeding after endoscopic papillectomy. METHODS : Patients (n = 80) with suspected benign adenomas on the major papilla who were scheduled for endoscopic papillectomy with or without clipping were randomized. A new duodenoscope-compatible clip capable of being rotated, reopened, and repeatedly repositioned was used. The primary end point was incidence of delayed bleeding. RESULTS : The clipping procedure was successful in all patients. The incidence of delayed bleeding was nonsignificantly higher in the no-clipping group than in the clipping group (31.6 % [95 % confidence interval (CI) 19.1-47.5] vs. 15.0 % [95 %CI 7.1-29.1]). The incidence of post-endoscopic retrograde cholangiopancreatography pancreatitis did not differ significantly between the groups (clipping vs. no-clipping: 17.5 % [95 %CI 8.7-31.9] vs. 5.3 % [95 %CI 1.5-17.3]), and all cases were mild. CONCLUSIONS : Placement of the newly designed rotatable clip was technically feasible and tended to have a protective effect by preventing delayed bleeding after endoscopic papillectomy, although statistical significance was not reached.

Clinical outcomes of EUS-guided radiofrequency ablation for unresectable pancreatic cancer: A prospective observational study.

BACKGROUND AND OBJECTIVES: EUS-guided radiofrequency ablation (EUS-RFA) has been increasingly used for the treatment of pancreatic neoplasms. The role of EUS-RFA in the management of pancreatic cancer has not yet been elucidated. This study aimed to evaluate the survival impact of EUS-RFA in unresectable pancreatic cancer. METHODS: Twenty-two patients (n = 14, locally advanced unresectable; n = 8, metastatic) with unresectable pancreatic cancer underwent EUS-RFA combined with subsequent chemotherapy between May 2016 and June 2019. Survival outcomes including overall survival (OS) and progression-free survival (PFS) were evaluated. RESULTS: EUS-RFA was successful in all patients. The median number of RFA sessions was 5 (interquartile range, [IQR], 3.25-5.75). After successful EUS-RFA, subsequent gemcitabine-based chemotherapy was performed. Early procedure-related adverse events occurred in 4 out of 107 sessions (3.74%), including peritonitis (n = 1) and abdominal pain (n = 3). During follow-up over a median of 21.23 months (IQR, 10.73-27.1), the median OS and PFS were 24.03 months (95% confidence interval [CI], 16-35.8) and 16.37 months (95% CI, 8.87-19), respectively. CONCLUSIONS: EUS-RFA is technically feasible and safe for the management of unresectable pancreatic cancer. EUS-RFA combined with systemic chemotherapy may be associated with favorable survival outcomes. Further larger-scale prospective comparative study is required to confirm these findings.

Graphene optical modulators using bound states in the continuum.

Graphene-based optical modulators have been widely investigated due to the high mobility and tunable permittivity of graphene. However, achieving a high modulation depth with a low insertion loss is challenging owing to low graphene-light interaction. To date, only waveguide-type modulators have been extensively studied to improve light-graphene interaction, and few free-space type modulators have been demonstrated in the optical communication wavelength range. In this study, we propose two graphene-based optical free-space type modulators in a simple silicon photonic crystal structure that supports bound states in the continuum. The designed modulator with an ultra-high quality factor from the bound states in the continuum achieves a high modulation depth (MD = 0.9972) and low insertion loss (IL = 0.0034) with a small Fermi level change at the optical communication wavelength. In addition, the proposed modulators support outstanding modulation performance in the normal chemical vapor deposition (CVD) graphene (mobility = 0.5 m2/Vs). We believe the scheme may pave the way for graphene-based optical active devices.

Efficacy and safety of EUS-guided through-the-needle microforceps biopsy sampling in categorizing the type of pancreatic cystic lesions.

BACKGROUND AND AIMS: EUS-guided through-the-needle biopsy sampling (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 PCLs 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: Forty-five patients were analyzed. EUS-TTNB was successfully performed in all patients (technical success, 100%). Histologic diagnosis of PCLs was made in 37 patients (diagnostic yield, 82%). When comparing EUS-TTNB with a 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 fewer than 4 visible biopsy specimens per session (67%; P = .045). During follow-up, 3 patients (7%) 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.

The impact of preoperative EUS-FNA for distal resectable pancreatic cancer: Is it really effective enough to take risks?

BACKGROUND AND AIMS: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is frequently used for the preoperative histologic diagnosis of pancreatic cancer. However, debate continues regarding the clinical merits of preoperative EUS-FNA for the management of resectable pancreatic cancer. We aimed to evaluate the benefits and safety of preoperative EUS-FNA for resectable distal pancreatic cancer. METHODS: The medical records of 304 consecutive patients with suspected distal pancreatic cancer who underwent EUS-FNA were retrospectively reviewed to evaluate the clinical benefits of preoperative EUS-FNA. We also reviewed the medical records of 528 patients diagnosed with distal pancreatic cancer who underwent distal pancreatectomy with or without EUS-FNA. The recurrence rates and cancer-free survival periods of patients who did or did not undergo preoperative EUS-FNA were compared. RESULTS: The diagnostic accuracy of preoperative EUS-FNA was high (sensitivity, 87.5%; specificity, 100%; positive predictive value 100%; accuracy, 90.7%; negative predictive value, 73.8%). Among patients, 26.7% (79/304) avoided surgery based on the preoperative EUS-FNA findings. Of the 528 patients who underwent distal pancreatectomy, 193 patients received EUS-FNA and 335 did not. During follow-up (median 21.7 months), the recurrence rate was similar in the two groups (EUS-FNA, 72.7%; non-EUS-FNA, 75%; P = 0.58). The median cancer-free survival was also similar (P = 0.58); however, gastric wall recurrence was only encountered in the patients with EUS-FNA (n = 2). CONCLUSION: Preoperative EUS-FNA is not associated with increased risks of cancer-specific or overall survival. However, clinicians must consider the potential risks of needle tract seeding, and care should be taken when selecting patients.

Clinical utility of directional eFLOW compared with contrast-enhanced harmonic endoscopic ultrasound for assessing the vascularity of pancreatic and peripancreatic masses.

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 < 0.05). 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.

Effectiveness of early endoscopic ultrasound-guided drainage for postoperative fluid collection.

BACKGROUND: Postoperative abdominal fluid collections (PAFCs) are a potentially fatal complication of pancreatobiliary surgery. Endoscopic ultrasound (EUS)-guided drainage has recently been shown to be effective in treating PAFCs of more than 4 weeks old. Little is currently known, however, regarding the EUS-guided drainage of PAFCs of less than 4 weeks. This study assessed the efficacy and safety of the early drainage (< 4 weeks) of PAFCs via EUS guidance. METHODS: The data of patients who had undergone EUS-guided PAFC drainage between July 2008 and January 2018 were retrospectively analyzed. Data of EUS-guided PAFC drainage were obtained from prospectively collected EUS database of our institute and reviewed of patients' clinical parameters based on electrical medical record. RESULTS: A total of 48 patients who had undergone EUS-guided PAFC drainage within 4 weeks of pancreatobiliary surgery were enrolled. The indications of procedure included abdominal pain (n = 27), fever (n = 18), leukocytosis (n = 2), and increased size of PAFC during external tube drainage (n = 1). Technical success was achieved in all cases, and the clinical success rate was 95.8% (46/48). Four patients underwent secondary procedures. The median period from surgery to EUS-guide drainage was 14 days (Interquartile range [IQR] 10-16), and median time to resolution was 23.5 days (IQR 8.5-33.8). Adverse events occurred in two cases that were developed intracystic bleeding and were successfully resolved by arterial coil embolization. CONCLUSIONS: Early EUS-guided drainage is a technically feasible, effective, and safe method in patients who have developing PAFCs within 4 weeks of pancreatobiliary surgery.