Adaptive Algorithm for Fast 3D Characterization of Magnetic Sensors

Magnetic sensors are highly relevant in clinical and industrial applications such as localization tasks and geological investigations. The spatial behavior of these sensors is of great interest for accurate forward modeling and the consequential possibilities for sophisticated applications, e.g., solutions to inverse problems. In this contribution, we present a novel characterization approach using adaptive system identification approaches. We utilize a gradient-based algorithm for estimating impulse and corresponding frequency responses for a directivity analysis in 1D, 2D, and 3D. For this, we built a triaxial Helmholtz coil setup to generate a 3D directive field. This is controlled by an algorithm that exploits similarities in sensor behavior with respect to small differences in excitation field angles. We found advantages for a controlled adaptation, with faster convergence and a smaller system distance between estimations and measurements with a proposed control based on the contraction-expansion approach (CEA). With runtimes averaging less than 1.5 s per direction for full impulse response estimation, this proof of concept shows the potential of the proposed algorithm for enabling a feasible frequency and directivity characterization method

Stent placement in pancreatic disease, when, which and why? – a current perspective

IntroductionStenting of the pancreas is a challenging task for the interventional gastroenterologist. The indications for pancreatic stent implantation are either prophylactic or therapeutic. We give an overview of currently available literature and techniques for the respective indications of pancreatic stent placement.MethodsA structured literature research was conducted (Pubmed.gov) primarily using the following key words: interventional endoscopy, pancreatic stenting, post-ERCP pancreatitis, pancreatic Q8 fistulae, pancreas divisum.ResultsProphylactic stent implantation aims to prevent PEP by using thin (3-5 Fr) and short (3-5 cm) designated pancreatic stents at least in high-risk patients. Therapeutic stent placement is intended to restore the proper flow of pancreatic secretion with stenoses, leaks, fistulas or anatomical malformation of the pancreatic duct. Depending on the etiology, plastic stents or SEMSs are used. Another field of pancreatic stenting represents EUS-guided puncture with stent implantation as an alternative access to the main pancreatic duct when transpapillary access is impossible. In addition to the implantation of plastic stents, which achieve good results, LAMS implantation can be discussed as an alternative access route.DiscussionThe field of pancreatic stenting is complex and belongs in the hands of experienced endoscopists in specialized institutions. This can ensure that the patient receives the optimal treatment with the best possible outcome

Quality standards and curriculum for training in cholangiopancreatoscopy : European Society of Gastrointestinal Endoscopy (ESGE) Position Statement

Competence in cholangioscopy should be defined as the ability to successfully perform the procedure effectively, without trainer assistance, in 80 % of procedures. Cholangioscopy should be performed in endoscopy units with a high yearly volume of endoscopic retrograde cholangiopancreatographies (ERCPs) of all grades of complexity. Cholangiopancreatoscopy practice should be considered as standard or advanced as follows: - STANDARD : Cholangioscopy for extrahepatic biliary stones; evaluation of extrahepatic biliary strictures; selective ductal guidewire cannulation and removal of migrated biliary stents/foreign body extraction - ADVANCED : Cholangioscopy for intrahepatic biliary strictures or complex hepatolithiasis; percutaneous cholangioscopy and pancreatoscopy. Endoscopy units undertaking standard cholangioscopy should have prompt access to the following (on site or within a defined rapidly responsive network): - Endoscopic ultrasound (EUS)- Interventional radiology (on-site) and hepaticopancreaticobiliary (HPB) surgery - HPB multidisciplinary meetings (MDMs). Complete extrahepatic stone clearance at the initial cholangioscopy session should be successful in 80 % of intention-to-treat cases. Cholangioscopy is recommended with visually guided biopsies in the evaluation of undefined biliary strictures, ideally at index ERCP to prevent negative visual and histological effects of prior stenting; except in cases with an associated mass lesion that may allow tissue acquisition by other means (e. g. EUS or percutaneous biopsy). In cholangioscopic evaluation of extrahepatic biliary strictures, visual assessment should be achieved in > 90 % of cases, and at least 4 visually guided biopsies should be undertaken with sufficient tissue for histological assessment being obtained in > 80 % of cases. Percutaneous transhepatic cholangioscopy is indicated in patients with transhepatic bile duct access in cases of altered anatomy or failed ERCP and an indication for cholangioscopy (stone management; biliary stricture evaluation; foreign body removal). Cholangioscopy is considered an advanced adjunct to ERCP, and prior to undertaking supervised cholangioscopic procedures trainees should be competent in the basic skills of ERCP (Schutz level 1 and 2) as defined by ESGE (duodenal intubation; biliary cannulation; distal bile duct stenting; ≤ 10-mm stone extraction). Cholangioscopy training should take place in expert referral centers with a high volume of ERCP and cholangioscopy cases. A trainee's principal trainer should be an experienced trainer ideally with at least 3 years of experience in undertaking independent cholangioscopy to the determined quality standards. Competence in cholangioscopy should be defined as the ability to successfully perform the procedure effectively without trainer assistance in 80 % of procedures

Digital single-operator pancreatoscopy for the treatment of symptomatic pancreatic duct stones: a prospective multicenter cohort trial

BACKGROUND  Digital single-operator pancreatoscopy (DSOP)-guided lithotripsy is a novel treatment modality for pancreatic endotherapy, with demonstrated technical success in retrospective series of between 88 % and 100 %. The aim of this prospective multicenter trial was to systematically evaluate DSOP in patients with chronic pancreatitis and symptomatic pancreatic duct stones. METHODS  Patients with symptomatic chronic pancreatitis and three or fewer stones ≥ 5mm in the main pancreatic duct (MPD) of the pancreatic head or body were included. The primary end point was complete stone clearance (CSC) in three or fewer treatment sessions with DSOP. Current guidelines recommend extracorporeal shock wave lithotripsy (ESWL) for MPD stones > 5 mm. A performance goal was developed to show that the CSC rate of MPD stones using DSOP was above what has been previously reported for ESWL. Secondary end points were pain relief measured with the Izbicki pain score (IPS), number of interventions, and serious adverse events (SAEs). RESULTS  40 chronic pancreatitis patients were included. CSC was achieved in 90 % of patients (36/40) on intention-to-treat analysis, after a mean (SD) of 1.36 (0.64) interventions (53 procedures in total). The mean (SD) baseline IPS decreased from 55.3 (46.2) to 10.9 (18.3). Overall pain relief was achieved in 82.4 % (28/34) after 6 months of follow-up, with complete pain relief in 61.8 % (21/34) and partial pain relief in 20.6 % (7/34). SAEs occurred in 12.5 % of patients (5/40), with all treated conservatively. CONCLUSION  DSOP-guided endotherapy is effective and safe for the treatment of symptomatic MPD stones in highly selected patients with chronic pancreatitis. It significantly reduces pain and could be considered as an alternative to standard ERCP techniques for MPD stone treatment in these patients

Imaging Inflammation - From Whole Body Imaging to Cellular Resolution

Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the future prospects of the imaging technologies for clinical applications in precision medicine from the pre-clinical development point of view

Open Surgical versus Minimal Invasive Necrosectomy of the Pancreas-A Retrospective Multicenter Analysis of the German Pancreatitis Study Group

Background Necrotising pancreatitis, and particularly infected necrosis, are still associated with high morbidity and mortality. Since 2011, a step-up approach with lower morbidity rates compared to initial open necrosectomy has been established. However, mortality and complication rates of this complex treatment are hardly studied thereafter. Methods The German Pancreatitis Study Group performed a multicenter, retrospective study including 220 patients with necrotising pancreatitis requiring intervention, treated at 10 hospitals in Germany between January 2008 and June 2014. Data were analysed for the primary endpoints "severe complications" and "mortality" as well as secondary endpoints including "length of hospital stay", "follow up", and predisposing or prognostic factors. Results Of all patients 13.6% were treated primarily with surgery and 86.4% underwent a step-up approach. More men (71.8%) required intervention for necrotising pancreatitis. The most frequent etiology was biliary (41.4%) followed by alcohol (29.1%). Compared to open necrosectomy, the step-up approach was associated with a lower number of severe complications (primary composite endpoint including sepsis, persistent multiorgan dysfunction syndrome (MODS) and erosion bleeding: 44.7% vs. 73.3%), lower mortality (10.5% vs. 33.3%) and lower rates of diabetes mellitus type 3c (4.7% vs. 33.3%). Low hematocrit and low blood urea nitrogen at admission as well as a history of acute pancreatitis were prognostic for less complications in necrotising pancreatitis. A combination of drainage with endoscopic necrosectomy resulted in the lowest rate of severe complications. Conclusion A step-up approach starting with minimal invasive drainage techniques and endoscopic necrosectomy results in a significant reduction of morbidity and mortality in necrotising pancreatitis compared to a primarily surgical intervention

The Iceberg Phenomenon: As Soon as One Technological Problem in NOTES Is Solved, the Next One Appears!

Purpose. Though already proclaimed about 7 years ago, natural orifice transluminal endoscopic surgery (NOTES) is still in its early stages. A multidisciplinary working team tried to analyze the technical obstacles and identify potential solutions. Methods. After a comprehensive review of the literature, a group of 3 surgeons, 1 gastroenterologist, 10 engineers, and 1 representative of biomedical industry defined the most important deficiencies within the system and then compiled as well as evaluated innovative technologies that could be used to help overcome these problems. These technologies were classified with regard to the time needed for their implementation and associated hindrances, where priority is based on the level of impact and significance that it would make. Results. Both visualization and actuation require significant improvement. Advanced illumination, mist elimination, image stabilization, view extension, 3-dimensional stereoscopy, and augmented reality are feasible options and could optimize visual information. Advanced mechatronic platforms with miniaturized, powerful actuators, and intuitive human–machine interfaces could optimize dexterity, as long as enabling technologies are used. The latter include depth maps in real time, precise navigation, fast pattern recognition, partial autonomy, and cognition systems. Conclusion. The majority of functional deficiencies that still exist in NOTES platforms could be overcome by a broad range of already existing or emerging enabling technologies. To combine them in an optimal manner, a permanent dialogue between researchers and clinicians is mandatory

Increased intestinal permeability and tight junction disruption by altered expression and localization of occludin in a murine graft versus host disease model

<p>Abstract</p> <p>Background</p> <p>Hematopoietic stem cell transplantation is increasingly performed for hematologic diseases. As a major side effect, acute graft versus host disease (GvHD) with serious gastrointestinal symptoms including diarrhea, gastrointestinal bleeding and high mortality can be observed. Because surveillance and biopsies of human gastrointestinal GvHD are difficult to perform, rare information of the alterations of the gastrointestinal barrier exists resulting in a need for systematic animal models.</p> <p>Methods</p> <p>To investigate the effects of GvHD on the intestinal barrier of the small intestine we utilized an established acute semi allogenic GvHD in C57BL/6 and B6D2F1 mice.</p> <p>Results</p> <p>By assessing the differential uptake of lactulose and mannitol in the jejunum, we observed an increased paracellular permeability as a likely mechanism for disturbed intestinal barrier function. Electron microscopy, immunohistochemistry and PCR analysis indicated profound changes of the tight-junction complex, characterized by downregulation of the tight junction protein occludin without any changes in ZO-1. Furthermore TNF-α expression was significantly upregulated.</p> <p>Conclusions</p> <p>This analysis in a murine model of GvHD of the small intestine demonstrates serious impairment of intestinal barrier function in the jejunum, with an increased permeability and morphological changes through downregulation and localization shift of the tight junction protein occludin.</p