Shou-Jiang Tang

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part III): in vivo endoscopic imaging of blood flow in the rat and human gastrointestinal tracts

We previously described a fiber based Doppler optical coherence tomography system [1] capable of imaging embryo cardiac blood flow at 4~16 frames per second with wide velocity dynamic range [2]. Coupling this system to a linear scanning fiber optical catheter design that minimizes friction and vibrations, we report here the initial results of in vivo endoscopic Doppler optical coherence tomography (EDOCT) imaging in normal rat and human esophagus. Microvascular flow in blood vessels less than 100 microm diameter was detected using a combination of color-Doppler and velocity variance imaging modes, during clinical endoscopy using a mobile EDOCT system.

Given capsule endoscopy in celiac disease: evaluation of diagnostic accuracy and interobserver agreement.

BACKGROUND AND AIMS:Capsule endoscopy (CE) has been increasingly used for diagnosing diseases of the small bowel. It is an attractive technique for assessing celiac disease (CD) because it is noninvasive and provides a close and magnified view of the mucosa of the entire small bowel. In this study, we evaluated the accuracy of CE and interobserver agreement in recognizing villous atrophy (VA) using histopathology as the reference. We also explored the extent of small bowel involvement with CD and the relationship between the length of the affected bowel and the clinical presentation.METHODS:Ten CD patients with histologically proven VA and the same number of controls were subjected to CE. Four, blinded to histology findings, investigators (two with and two without prestudy CE experience) were asked to diagnose VA on CE images.RESULTS:Based on assessment of all four investigators, the overall sensitivity, specificity, PPV, and NPV of CE in diagnosing VA were 70%, 100%, 100%, and 77%, respectively. The sensitivity and the specificity of the test was 100% when the reports of experienced capsule endoscopists only were analyzed. The interobserver agreement was perfect (κ= 1.0) between investigators with prestudy CE experience and poor (κ= 0.2) between the investigators who had limited prestudy exposure to CE. Celiac patients with extensive small bowel involvement had typical symptoms of malabsorption (diarrhea, weight loss) as opposed to mild and nonspecific symptoms in patients whose disease was limited to the proximal small bowel. CE was tolerated well by all study participants with 95% reporting absence of any discomfort.CONCLUSIONS:Although based on a small sample size, the study suggests that CE may be useful in assessing patients with CD. Familiarity with CE technology appears to be a critical factor affecting the accuracy of the test. Larger studies are warranted to more precisely define the advantages and limitations of CE in CD.

Endoscopic Doppler optical coherence tomography in the human GI tract: initial experience

BACKGROUND Expanding the current endoscopic optical coherence tomography (OCT) system with Doppler capability may augment this novel high-resolution cross-sectional imaging technique with functional blood flow information. The aim of this feasibility study was to assess the clinical feasibility of an endoscopic Doppler OCT (EDOCT) system in the human GI tract. METHODS During routine endoscopy, 22 patients were imaged by using a prototype EDOCT system, which provided color-Doppler and velocity-variance images of mucosal and submucosal blood flow at one frame per second, simultaneously with high-spatial-resolution (10-25 mum) images of tissue microstructure. The images were acquired from normal GI tract and pathologic tissues. OBSERVATIONS Subsurface microstructure and microcirculation images of normal and pathologic GI tissues, including Barretts esophagus, esophageal varices, portal hypertensive gastropathy, gastric antral vascular ectasia, gastric lymphoma, and duodenal adenocarcinoma, were obtained from 72 individual sites in vivo. Differences in vessel diameter, distribution, density, and blood-flow velocity were observed among the GI tissue pathologies imaged. CONCLUSIONS To our knowledge, this is the first study to demonstrate the feasibility of EDOCT imaging in the human GI tract during routine endoscopy procedures. EDOCT may detect the different microcirculation patterns exhibited by normal and diseased tissues, which may be useful for diagnostic imaging and treatment monitoring.

Safety and utility of ERCP during pregnancy

BACKGROUND ERCP is an important diagnostic and therapeutic tool in patients with biliary and pancreatic disease. Its utility and safety during pregnancy is largely unknown because it is not often required and because its use has been only infrequently reported in the published literature. OBJECTIVE Our purpose was to report the clinical experience with ERCP during pregnancy. DESIGN Retrospective review, single academic center. PATIENTS All (consecutive) pregnant women who underwent ERCP at Parkland Memorial Hospital from 2000 to 2006. MAIN OUTCOME MEASUREMENTS History, clinical data, hospital course, procedure-related complication rates and outcomes, and delivery and fetal outcomes were abstracted from medical records. RESULTS During the study period, 68 ERCPs were performed on 65 pregnant women. The calculated ERCP rate was 1 per 1415 births. The common indications for ERCP in pregnancy were recurrent biliary colic, abnormal liver function tests, and dilated bile duct on US. ERCP was technically successful in all patients. The median fluoroscopy time was 1.45 minutes (range 0-7.2 minutes). There was no perforation, sedation-related adverse event, postsphincterotomy bleeding, cholangitis, or procedure-related maternal or fetal deaths. Post-ERCP pancreatitis was diagnosed in 11 patients (16%). None of these 11 patients had local or systemic complications. Fifty-nine patients had complete follow-up. Endoscopic therapy at the time of ERCP was undertaken in all patients. Furthermore, 9 patients (32.1%) underwent cholecystectomy in the first and second trimesters for either acute cholecystitis (6) or symptomatic gallstones (3). Term pregnancy was achieved in 53 patients (89.8%). Patients having ERCP in the first trimester had the lowest percentage of term pregnancy (73.3%) and the highest risk of preterm delivery (20.0%) and low-birth-weight newborns (21.4%). None of the 59 patients with long-term follow-up had spontaneous fetal loss, perinatal death, stillbirth, or fetal malformation. LIMITATION Retrospective review. CONCLUSIONS ERCP can be performed safely during pregnancy. Further, ERCP performed in pregnancy leads to specific therapy in essentially all patients. However, ERCP may be associated with a higher rate of post-ERCP pancreatitis than in the general population.

Complete transvaginal NOTES nephrectomy using magnetically anchored instrumentation.

BACKGROUND AND PURPOSE Evolution of minimally invasive techniques has prompted interest in natural orifice transluminal endoscopic surgery (NOTES). Challenges for NOTES include loss of instrument rigidity, reduction in working envelopes, and collision of instrumentation. Magnetic anchoring and guidance system (MAGS) is one surgical innovation developed at our institution whereby instruments that are deployed intra-abdominally are maneuvered by the use of an external magnet. We present our initial animal experience with complete transvaginal NOTES nephrectomy using MAGS technology. MATERIALS AND METHODS Transvaginal NOTES nephrectomy was performed in two female pigs through a vaginotomy, using a 40-cm dual-lumen rigid access port inserted into the peritoneal cavity. A MAGS camera and cauterizer were deployed through the port and manipulated across the peritoneal surface by way of magnetic coupling via an external magnet. A prototype 70-cm articulating laparoscopic grasper introduced through the vaginal access port facilitated dissection after deployment of the MAGS instruments. The renal artery and vein were stapled en-bloc using an extra-long articulating endovascular stapler. RESULTS NOTES nephrectomies were successfully completed in both pigs without complications using MAGS instrumentation. The MAGS camera provided a conventional umbilical perspective of the kidney; the cauterizer, transvaginal grasper, and stapler preserved triangulation while avoiding instrument collisions. Operative duration for the two cases was 155 and 125 minutes, and blood loss was minimal. CONCLUSIONS NOTES nephrectomy using MAGS instrumentation is feasible. We believe this approach improves shortcomings of previously reported NOTES nephrectomies in that triangulation, instrument fidelity, and visualization are preserved while hilar ligation is performed using a conventional stapler without need for additional transabdominal trocars.

Automatic classification of digestive organs in wireless capsule endoscopy videos

Wireless Capsule Endoscopy (WCE) allows a physician to examine the entire small intestine without any surgical operation. With the miniaturization of wireless and camera technologies the ability comes to view the entire gestational track with little effort. Although WCE is a technical break-through that allows us to access the entire intestine without surgery, it is reported that a medical clinician spends one or two hours to assess a WCE video, It limits the number of examinations possible, and incur considerable amount of costs. To reduce the assessment time, it is critical to develop a technique to automatically discriminate digestive organs such as esophagus, stomach, small intestinal (i.e., duodenum, jejunum, and ileum) and colon. In this paper, we propose a novel technique to segment a WCE video into these anatomic parts based on color change pattern analysis. The basic idea is that the each digestive organ has different patterns of intestinal contractions that are quantified as the features. We present the experimental results that demonstrate the effectiveness of the proposed method.

Managing anticoagulation and antiplatelet medications in GI endoscopy: a survey comparing the East and the West

BACKGROUND Anticoagulation and antiplatelet medications may potentiate GI bleeding, and their use may lead to an increased need for a GI endoscopy. We hypothesized that there might be different practice patterns among international endoscopists. OBJECTIVE To explore the differences in management practices for patients who receive anticoagulation and antiplatelet medications from Eastern and Western endoscopists. DESIGN International survey study. SETTING Academic medical centers and private clinics. SUBJECTS Members of the American Society for Gastrointestinal Endoscopy (ASGE) in Eastern (Korea, Japan, China, India, Thailand, Singapore, Malaysia, and Philippines) and Western (United States and Canada) countries were invited to complete a Web-site-based questionnaire. In addition, the questionnaire was sent to university hospitals in South Korea and academic institutions in the United States. METHODS A survey was administered that contained detailed questions about the use of an endoscopy in patients on anticoagulation and antiplatelet medications. MAIN OUTCOME MEASUREMENTS Different opinions and clinical practice patterns regarding the use of anticoagulation and antiplatelet medications by Eastern and Western endoscopists. RESULTS A total of 105 Eastern and 106 Western endoscopists completed the survey. Western endoscopists experienced more instances of procedure-related bleeding (P = .003) and thromboembolism after withdrawal of medications (P = .016). Eastern endoscopists restarted medications later (1-3 days) than Western endoscopists after a biopsy (same day) (P < .001). Eastern endoscopists withdrew aspirin for more than 7 days before a polypectomy and then restarted it 1 to 3 days after a polypectomy, whereas Western endoscopists performed a polypectomy without withdrawing aspirin (P < .001). ASGE guidelines were followed less often by Eastern than by Western endoscopists (P < .001). LIMITATIONS Low response rate, heterogeneity of the sample, and recall bias. CONCLUSIONS The opinions and clinical practice patterns for the management of anticoagulation and antiplatelet medications differed significantly between Eastern and Western endoscopists. The lack of uniformity in practice patterns suggests that more data and better education are required in the area of GI endoscopy for patients on anticoagulation and antiplatelet medications, particularly given that individual patient characteristics may be associated with unique types of complications.

An Implantable, Batteryless, and Wireless Capsule With Integrated Impedance and pH Sensors for Gastroesophageal Reflux Monitoring

In this study, a device for gastroesophageal reflux disease (GERD) monitoring has been prototyped. The system consists of an implantable, batteryless and wireless transponder with integrated impedance and pH sensors; and a wearable, external reader that wirelessly powers up the transponder and interprets the transponded radio-frequency signals. The transponder implant with the total size of 0.4 cm ×0.8 cm ×3.8 cm harvests radio frequency energy to operate dual-sensor and load-modulation circuitry. The external reader can store the data in a memory card and/or send it to a base station wirelessly, which is optional in the case of multiple-patient monitoring in a hospital or conducting large-scale freely behaving animal experiments. Tests were carried out to verify the signal transduction reliability in different situations for antenna locations and orientation. In vitro, experiments were conducted in a mannequin model by positioning the sensor capsule inside the wall of a tube mimicking the esophagus. Different liquids with known pH values were flushed through the tube creating reflux episodes and wireless signals were recorded. Live pigs under anesthesia were used for the animal models with the transponder implant attached on the esophageal wall. The reflux episodes were created while the sensor data were recorded wirelessly. The data were compared with those recorded independently by a clinically used wireless pH sensor capsule placed next to our implant transponder. The results showed that our transponder detected every episode in both acid and non-acid nature, while the commercial pH sensor missed events that had similar, repeated pH values, and failed to detect pH values higher than 10. Our batteryless transponder does not require a battery thus allowing longer diagnosis and prognosis periods to monitor drug efficacy, as well as providing accurate assessment of GERD symptoms.

Synthetic Lethality of Yeast slt Mutations with U2 Small Nuclear RNA Mutations Suggests Functional Interactions between U2 and U5 snRNPs That Are Important for Both Steps of Pre-mRNA Splicing

ABSTRACT A genetic screen was devised to identify Saccharomyces cerevisiae splicing factors that are important for the function of the 5′ end of U2 snRNA. Six slt (stands for synthetic lethality with U2) mutants were isolated on the basis of synthetic lethality with a U2 snRNA mutation that perturbs the U2-U6 snRNA helix II interaction. SLT11 encodes a new splicing factor andSLT22 encodes a new RNA-dependent ATPase RNA helicase (D. Xu, S. Nouraini, D. Field, S. J. Tang, and J. D. Friesen, Nature 381:709–713, 1996). The remaining four sltmutations are new alleles of previously identified splicing genes:slt15, previously identified as prp17(slt15/prp17-100), slt16/smd3-1,slt17/slu7-100, and slt21/prp8-21. slt11-1 andslt22-1 are synthetically lethal with mutations in the 3′ end of U6 snRNA, a region that affects U2-U6 snRNA helix II; however,slt17/slu7-100 and slt21/prp8-21 are not. This difference suggests that the latter two factors are unlikely to be involved in interactions with U2-U6 snRNA helix II but rather are specific to interactions with U2 snRNA. Pairwise synthetic lethality was observed among slt11-1 (which affects the first step of splicing) and several second-step factors, includingslt15/prp17-100, slt17/slu7-100, andprp16-1. Mutations in loop 1 of U5 snRNA, a region that is implicated in the alignment of the two exons, are synthetically lethal with slu4/prp17-2 and slu7-1 (D. Frank, B. Patterson, and C. Guthrie, Mol. Cell. Biol. 12:5179–5205, 1992), as well as with slt11-1, slt15/prp17-100,slt17/slu7-100, and slt21/prp8-21. These same U5 snRNA mutations also interact genetically with certain U2 snRNA mutations that lie in the helix I and helix II regions of the U2-U6 snRNA structure. Our results suggest interactions among U2 snRNA, U5 snRNA, and Slt protein factors that may be responsible for coupling and coordination of the two reactions of pre-mRNA splicing.

Human Immunodeficiency Virus-Associated Gastrointestinal Disease: Common Endoscopic Biopsy Diagnoses

The gastrointestinal (GI) tract is a major site of disease in HIV infection: almost half of HIV-infected patients present with GI symptoms, and almost all patients develop GI complications. GI symptoms such as anorexia, weight loss, dysphagia, odynophagia, abdominal pain, and diarrhea are frequent and usually nonspecific among these patients. Endoscopy is the diagnostic test of choice for most HIV-associated GI diseases, as endoscopic and histopathologic evaluation can render diagnoses in patients with non-specific symptoms. In the past three decades, studies have elucidated a variety of HIV-associated inflammatory, infectious, and neoplastic GI diseases, often with specific predilection for various sites. HIV-associated esophageal disease, for example, commonly includes candidiasis, cytomegalovirus (CMV) and herpes simplex virus (HSV) infection, Kaposis sarcoma (KS), and idiopathic ulceration. Gastric disease, though less common than esophageal disease, frequently involves CMV, Mycobacterium avium-intracellulare (MAI), and neoplasia (KS, lymphoma). Small bowel biopsies and intestinal aspirates from HIV-infected patients often show HIV enteropathy, MAI, protozoa (Giardia, Isospora, Cryptosporidia, amebae, Microsporidia), and helminths (Strongyloides stercoralis). Colorectal biopsies demonstrate viral (CMV, HSV), bacterial (Clostridia, Salmonella, Shigella, Campylobacter), fungal (cryptococcosis, histoplasmosis), and neoplastic (KS, lymphoma) processes. Herein, we review HIV-associated GI pathology, with emphasis on common endoscopic biopsy diagnoses.