EUS-Guided Choledochoduodenostomy for Distal Malignant Biliary Obstruction Using Electrocautery-Enhanced Lumen-Apposing Metal Stents: First US, Multicenter Experience.

BACKGROUND AND AIMS: EUS-guided biliary drainage has emerged as a technique to enable endobiliary drainage in failed ERCP. A newer model, lumen-apposing metal stents (LAMS), with a cautery-enhanced delivery system became available in the USA in late 2015. This cautery-tipped version may facilitate EUS-guided choledochoduodenostomy (EUS-CD), but data using this model are lacking. METHODS: We reviewed outcomes of attempted EUS-CD using cautery-enhanced LAMS from 6, US centers. The following data were collected: patient and procedure details, technical success, adverse events, clinical success (resolution of jaundice or improvement in bilirubin > 50%), and biliary re-interventions. RESULTS: EUS-CD was attempted in 67 patients (mean age 68.8) with malignant obstruction after failed ERCP between September 2015 and April 2018. EUS-CD was technically successful in 64 (95.5%). A plastic or metal stent was inserted through the lumen of the deployed LAMS in 50 of 64 (78.1%) patients to maintain a non-perpendicular LAMS axis into the bile duct. Adverse events occurred in 4 (6.3%) and included: abdominal pain (n = 2), peritonitis that responded to antibiotics (n = 1), and bleeding requiring transfusion (n = 1). Among 40 patients with follow-up of > 4 weeks, clinical success was achieved in 100%. Biliary re-interventions for obstruction were needed in 7(17.5%), in 3 of 6 (50.0%) that underwent EUS-CD with LAMS alone versus 4 of 34 (5%) with LAMS plus an axis-orienting stent (p = 0.02). CONCLUSION: EUS-CD using LAMS with cautery-enhanced delivery systems has high technical and clinical success rates, with a low rate of adverse events. Inserting an axis-orienting stent through the lumen of the LAMS may reduce the need for biliary re-interventions.

Immersogeometric cardiovascular fluid-structure interaction analysis with divergence-conforming B-splines.

This paper uses a divergence-conforming B-spline fluid discretization to address the long-standing issue of poor mass conservation in immersed methods for computational fluid-structure interaction (FSI) that represent the influence of the structure as a forcing term in the fluid subproblem. We focus, in particular, on the immersogeometric method developed in our earlier work, analyze its convergence for linear model problems, then apply it to FSI analysis of heart valves, using divergence-conforming B-splines to discretize the fluid subproblem. Poor mass conservation can manifest as effective leakage of fluid through thin solid barriers. This leakage disrupts the qualitative behavior of FSI systems such as heart valves, which exist specifically to block flow. Divergence-conforming discretizations can enforce mass conservation exactly, avoiding this problem. To demonstrate the practical utility of immersogeometric FSI analysis with divergence-conforming B-splines, we use the methods described in this paper to construct and evaluate a computational model of an in vitro experiment that pumps water through an artificial valve.

Projection-based stabilization of interface Lagrange multipliers in immersogeometric fluid-thin structure interaction analysis, with application to heart valve modeling.

This paper discusses a method of stabilizing Lagrange multiplier fields used to couple thin immersed shell structures and surrounding fluids. The method retains essential conservation properties by stabilizing only the portion of the constraint orthogonal to a coarse multiplier space. This stabilization can easily be applied within iterative methods or semi-implicit time integrators that avoid directly solving a saddle point problem for the Lagrange multiplier field. Heart valve simulations demonstrate applicability of the proposed method to 3D unsteady simulations. An appendix sketches the relation between the proposed method and a high-order-accurate approach for simpler model problems.

Combined high-field intraoperative magnetic resonance imaging and endoscopy increase extent of resection and progression-free survival for pituitary adenomas.

PURPOSE: The clinical benefit of combined intraoperative magnetic resonance imaging (iMRI) and endoscopy for transsphenoidal pituitary adenoma resection has not been completely characterized. This study assessed the impact of microscopy, endoscopy, and/or iMRI on progression-free survival, extent of resection status (gross-, near-, and sub-total resection), and operative complications. METHODS: Retrospective analyses were performed on 446 transsphenoidal pituitary adenoma surgeries at a single institution between 1998 and 2012. Multivariate analyses were used to control for baseline characteristics, differences during extent of resection status, and progression-free survival analysis. RESULTS: Additional surgery was performed after iMRI in 56/156 cases (35.9%), which led to increased extent of resection status in 15/156 cases (9.6%). Multivariate ordinal logistic regression revealed no increase in extent of resection status following iMRI or endoscopy alone; however, combining these modalities increased extent of resection status (odds ratio 2.05, 95% CI 1.21-3.46) compared to conventional transsphenoidal microsurgery. Multivariate Cox regression revealed that reduced extent of resection status shortened progression-free survival for near- versus gross-total resection [hazard ratio (HR) 2.87, 95% CI 1.24-6.65] and sub- versus near-total resection (HR 2.10; 95% CI 1.00-4.40). Complication comparisons between microscopy, endoscopy, and iMRI revealed increased perioperative deaths for endoscopy versus microscopy (4/209 and 0/237, respectively), but this difference was non-significant considering multiple post hoc comparisons (Fisher exact, p = 0.24). CONCLUSIONS: Combined use of endoscopy and iMRI increased pituitary adenoma extent of resection status compared to conventional transsphenoidal microsurgery, and increased extent of resection status was associated with longer progression-free survival. Treatment modality combination did not significantly impact complication rate.

Gastroduodenal ulcers on CT: forgotten, but not gone.

OBJECTIVE: To estimate the incidence of missed gastroduodenal ulcers on routine abdominal computed tomography (CT) and identify findings and methods to improve sensitivity of CT interpretation for peptic ulcers. MATERIALS AND METHODS: This is a retrospective chart and imaging review. Two blinded readers independently reviewed CTs performed within 7 days prior to endoscopy of 114 subjects; this included 57 consecutive subjects with proven gastroduodenal ulcers intermixed with 57 subjects with endoscopically normal examinations. Presence, location and size of ulcer crater, and ancillary findings (mural edema, asymmetric wall thickening, focal fat stranding, regional lymph nodes, and extraluminal gas) were recorded before and after review of multiplanar reformatted images. Radiology reports were then reviewed to determine if an ulcer was identified prospectively. RESULTS: Thirty-one ulcers (54%) were radiographically occult, missed by both readers. Thirteen ulcers were correctly and independently identified by both readers (sensitivity/specificity = 30%/100%). With review of multiplanar reformats, sensitivity and accuracy increased for both readers. When two or more ancillary findings were identified, the odds ratio of a true ulcer being present was greater than 5.6 (P = 0.0001). Both size and location of ulcer were important for detection; readers were more likely to identify gastric ulcers compared to duodenal or marginal ulcers (P = 0.02). Only 3/13 definitely visible ulcers were correctly identified during initial CT interpretation. CONCLUSIONS: Although CT has low sensitivity for peptic ulcer disease, the miss rate for visible peptic ulcers is high. Increased awareness, multiplanar imaging review, and identification of ancillary findings may improve sensitivity for gastroduodenal ulcers.

An immersogeometric variational framework for fluid-structure interaction: application to bioprosthetic heart valves.

In this paper, we develop a geometrically flexible technique for computational fluid-structure interaction (FSI). The motivating application is the simulation of tri-leaflet bioprosthetic heart valve function over the complete cardiac cycle. Due to the complex motion of the heart valve leaflets, the fluid domain undergoes large deformations, including changes of topology. The proposed method directly analyzes a spline-based surface representation of the structure by immersing it into a non-boundary-fitted discretization of the surrounding fluid domain. This places our method within an emerging class of computational techniques that aim to capture geometry on non-boundary-fitted analysis meshes. We introduce the term "immersogeometric analysis" to identify this paradigm. The framework starts with an augmented Lagrangian formulation for FSI that enforces kinematic constraints with a combination of Lagrange multipliers and penalty forces. For immersed volumetric objects, we formally eliminate the multiplier field by substituting a fluid-structure interface traction, arriving at Nitsche's method for enforcing Dirichlet boundary conditions on object surfaces. For immersed thin shell structures modeled geometrically as surfaces, the tractions from opposite sides cancel due to the continuity of the background fluid solution space, leaving a penalty method. Application to a bioprosthetic heart valve, where there is a large pressure jump across the leaflets, reveals shortcomings of the penalty approach. To counteract steep pressure gradients through the structure without the conditioning problems that accompany strong penalty forces, we resurrect the Lagrange multiplier field. Further, since the fluid discretization is not tailored to the structure geometry, there is a significant error in the approximation of pressure discontinuities across the shell. This error becomes especially troublesome in residual-based stabilized methods for incompressible flow, leading to problematic compressibility at practical levels of refinement. We modify existing stabilized methods to improve performance. To evaluate the accuracy of the proposed methods, we test them on benchmark problems and compare the results with those of established boundary-fitted techniques. Finally, we simulate the coupling of the bioprosthetic heart valve and the surrounding blood flow under physiological conditions, demonstrating the effectiveness of the proposed techniques in practical computations.

Modifications in endoscopic practice for pediatric patients.

We recommend that endoscopy in children be performed by pediatric-trained endoscopists whenever possible. We recommend that adult-trained endoscopists coordinate their services with pediatricians and pediatric specialists when they are needed to perform endoscopic procedures in children. We recommend that endoscopy be performed within 24 hours in symptomatic pediatric patients with known or suspected ingestion of caustic substances. We recommend emergent foreign-body removal of esophageal button batteries, as well as 2 or more rare-earth neodymium magnets. We recommend that procedural and resuscitative equipment appropriate for pediatric use should be readily available during endoscopic procedures. We recommend that personnel trained specifically in pediatric life support and airway management be readily available during sedated procedures in children. We recommend the use of endoscopes smaller than 6 mm in diameter in infants and children weighing less than 10 kg. We recommend the use of standard adult duodenoscopes for performing ERCP in children who weigh at least 10 kg. We recommend the placement of 12F or 16F percutaneous endoscopic gastrostomy tubes in children who weigh less than 50 kg.

Comprehensive volumetric optical microscopy in vivo.

Comprehensive volumetric microscopy of epithelial, mucosal and endothelial tissues in living human patients would have a profound impact in medicine by enabling diagnostic imaging at the cellular level over large surface areas. Considering the vast area of these tissues with respect to the desired sampling interval, achieving this goal requires rapid sampling. Although noninvasive diagnostic technologies are preferred, many applications could be served by minimally invasive instruments capable of accessing remote locations within the body. We have developed a fiber-optic imaging technique termed optical frequency-domain imaging (OFDI) that satisfies these requirements by rapidly acquiring high-resolution, cross-sectional images through flexible, narrow-diameter catheters. Using a prototype system, we show comprehensive microscopy of esophageal mucosa and of coronary arteries in vivo. Our pilot study results suggest that this technology may be a useful clinical tool for comprehensive diagnostic imaging for epithelial disease and for evaluating coronary pathology and iatrogenic effects.

Implementation and preliminary clinical experience with the use of ceiling mounted mobile high field intraoperative magnetic resonance imaging between two operating rooms.

OBJECTIVE: Intraoperative magnetic resonance imaging (ioMRI) provides immediate feedback and quality assurance enabling the neurosurgeon to improve the quality of a range of neurosurgical procedures. Implementation of ioMRI is a complex and costly process. We describe our preliminary 16 months experience with the integration of an IMRIS movable ceiling mounted high field (1.5 T) ioMRI setup with two operating rooms. METHODS: Aspects of implementation of our ioMRI and our initial 16 months of clinical experience in 180 consecutive patients were reviewed. RESULTS: The installation of a ceiling mounted movable ioMRI between two operating rooms was completed in April 2008 at Barnes-Jewish Hospital in St. Louis. Experience with 180 neurosurgical cases (M:F-100:80, age range 1-79 years, 71 gliomas, 57 pituitary adenomas, 9 metastases, 11 other tumor cases, 4 Chiari decompressions, 6 epilepsy resections and 22 other miscellaneous procedures) demonstrated that this device effectively provided high quality real-time intraoperative imaging. In 74 of all 180 cases (41%) and in 54% of glioma resections, the surgeon modified the procedure based upon the ioMRI. Ninety-three percent of ioMRI glioma cases achieved gross/near total resection compared to 65% of non ioMRI glioma cases in this time frame. CONCLUSION: A movable high field strength ioMRI can be safely integrated between two neurosurgical operating rooms. This strategy leads to modification of the surgical procedure in a significant number of cases, particularly for glioma surgery. Long-term follow up is needed to evaluate the clinical and financial impact of this technology in the field of neurosurgery.

A novel method for performing multiple wire insertions during endoscopic cyst gastrostomy.

BACKGROUND: Endoscopic cyst gastrostomy is effective in the management of uncomplicated pancreatic pseudocysts. A challenging aspect of the procedure is the insertion and confirmation of at least 2 guidewires into the cyst. Many technical procedures to accomplish the wire insertion have been described but are complicated. OBJECTIVE: We describe the use of a simple commercially available catheter that allows multiple wires to be inserted into a pancreatic pseudocyst as an efficient and simple means of performing a cyst gastrostomy. DESIGN: Case series. SETTING: Academic referral center. PATIENTS: Four consecutive patients undergoing EUS-guided cyst gastrostomy. INTERVENTIONS: A Haber ramp was used as the means for the introduction of multiple wires into a pancreatic pseudocyst. MAIN OUTCOME MEASUREMENTS: Technical success without loss of wire access during the cyst gastrostomy. RESULTS: Four patients underwent successful pancreatic cyst gastrostomy. There was no loss of wire access during the procedure. There were no intraprocedure or postprocedure complications. LIMITATIONS: Small patient population. CONCLUSIONS: The use of the Haber ramp provides a simple and efficient means for introducing, ensuring, and maintaining wire access during the creation of an endoscopic cyst gastrostomy.