Ian D. Norton

Mayo Clinic - Rochester, Rochester, Minnesota, United States

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Publications (51)281.44 Total impact

  • Ian D. Norton, Jonathan E. Clain
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    ABSTRACT: Many technical advances have offered enhanced capabilities in noninvasive imaging of the pancreas. Although these technical advances are impressive, current studies do not always define clearly the benefits that these advances will confer in patient management. A critical overview of these imaging modalities is offered here, with respect to diagnosis and patient management. Outcomes from various studies are summarized for modalities including transabdominal ultrasound, computed tomography, magnetic resonance imaging with and without pancreatography, and positron emission tomography.
    Current Gastroenterology Reports 04/2012; 2(2):120-124. DOI:10.1007/s11894-000-0095-8
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    ABSTRACT: Recent studies showed that endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) is a low-risk procedure for causing bacteremia and infectious complications when sampling solid lesions of the upper gastrointestinal (GI) tract. As a result, antibiotics are not recommended for prophylaxis against endocarditis. Our aim was to prospectively evaluate the risk of bacteremia and other infectious complications in patients undergoing EUS FNA of lower GI tract lesions. Patients referred for EUS FNA of lower GI tract lesions were considered for enrollment. Patients were excluded if there was an indication for preprocedure antibiotic administration based on American Society for Gastrointestinal Endoscopy guidelines, had taken antibiotics within the prior 7 days, or if they had a cystic lesion. Blood cultures were obtained immediately before the procedure, after flexible sigmoidoscopy/radial EUS, and 15 minutes after EUS FNA. One hundred patients underwent a total of 471 FNAs (mean, 4.7 FNAs/patient; range, 1-10 FNAs/patient). Blood cultures were positive in 6 patients. Cultures from 4 patients (4.0%, 95% confidence interval, 1.6%-9.8%) grew coagulase-negative Staphylococcus (n = 2), Peptostreptococcus stomatis (n = 1), or Moraxella (n = 1), which were considered contaminants. Two patients (2.0%, 95% confidence interval, 0.6%-7%) developed bacteremia: Bacteroides fragilis (n = 1) and Gemella morbillorum (n = 1). No signs or symptoms of infection developed in any patient. EUS FNA of solid lesions in the lower GI tract should be considered a low-risk procedure for infectious complications that does not warrant prophylactic administration of antibiotics for the prevention of bacterial endocarditis.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 07/2007; 5(6):684-9. DOI:10.1016/j.cgh.2007.02.029 · 6.53 Impact Factor
  • Gastrointestinal Endoscopy 04/2006; 63(5). DOI:10.1016/j.gie.2006.03.088 · 4.90 Impact Factor
  • Ian D. Norton
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    ABSTRACT: The optimal approach has yet to emerge for the management of sporadic periampullary adenomas and upper gastrointestinal (GI) neoplasia complicating familial adenomatous polyposis (FAP). There are no randomized trials comparing different surgical and/or endoscopic modalities. Such studies may not be feasible given the infrequency of these conditions and the long follow-up period required for such a study. In the meantime, selection of the optimal approach for an individual patient will rely on a careful evaluation of the disease severity and extent in that patient and the utilization of the best available endoscopic and surgical expertise.
    12/2005: pages 337-344;
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    ABSTRACT: The aim of the study was to examine whether endoscopic intralesional corticosteroid injection into recalcitrant peptic esophageal strictures reduces the need for repeat stricture dilation. Patients with a peptic esophageal stricture and recurrent dysphagia having had at least one dilation in the preceding 18 months were enrolled in a prospective randomized, double-blind study comparing steroid and sham injection. After endoscopic confirmation of recurrent stricture, patients were randomized to receive either 0.5 cc/quadrant triamcinolone (40 mg/cc) or sham injection into the stricture followed by balloon dilation of the stricture. Patients were stratified by the number of dilations required in the preceding 18 months, severity of dysphagia, the presence of esophagitis, stricture severity, and prior therapy with a proton-pump inhibitor. Patients and their physicians were blinded to the type of intervention received. Baseline dysphagia questionnaires were completed. Post-procedurally all patients were placed on a standardized proton-pump inhibitor regimen and standardized telephone follow-up questionnaires were completed at 1 wk and at 1, 3, 6, 9, and 12 months. The original sample-size calculation of 60 patients could not be met in a timely fashion because of a low incidence of recalcitrant peptic stricture patients. A total of 30 patients were enrolled, 15 in the steroid group (10 men, mean age 66 yr) and 15 in the sham group (11 M, mean age 67 yr). Patients were followed for 1 yr, unless they underwent an antireflux operation or died. Two patients, one per group, died of non-esophageal causes at 1 and 12 months. Four patients had fundoplication, two in each group, unrelated to stricture or dysphagia. Two patients in the steroid group (13%) and nine in the sham group (60%) required repeat dilation (p= 0.011). In patients with recalcitrant peptic esophageal stricture, steroid injection into the stricture combined with acid suppression significantly diminishes both the need for repeat dilation and the average time to repeat dilation compared to sham injection and acid suppression alone.
    The American Journal of Gastroenterology 12/2005; 100(11):2419-25. DOI:10.1111/j.1572-0241.2005.00331.x · 9.21 Impact Factor
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    ABSTRACT: Endoscopic biliary sphincterotomy has complication rates of 5%-12%. The output from the electrosurgical generator may influence the degree of coagulation and the rapidity of the incision, and thus rates of pancreatitis, hemorrhage, and perforation. Some modern generators incorporate feedback control to standardize output and automate the alternating cut and coagulation modes. Our aim was to compare 2 feedback-controlled generators, one with constant pure cutting-type output and the other with an alternating cut and coagulation mode. In this multicenter randomized study, 133 patients were assigned to the alternating cut/coag output and 134 patients were assigned to constant pure-cut output. Patients were stratified by their risk for pancreatitis. The overall pancreatitis rate was 1.5%, including 3 patients in the cut/coag group and 1 patient in the pure-cut group (P>.05). There were 11 poorly controlled (zipper) incisions in the pure-cut group and none in the cut/coag group (P=.02). The incision was completed in all patients without stalling. Immediate hemorrhage occurred in 35 pure-cut patients and 8 cut/coag patients output (P=.002). There were no episodes of clinically significant bleeding, delayed bleeding, or perforation. Biliary sphincterotomy using feedback-controlled generators results in dependable progression of incision with a low pancreatitis rate. Control of the incision is improved subjectively with the cut/coagulation output, but this did not translate into a difference in clinically significant complications.
    Clinical Gastroenterology and Hepatology 11/2005; 3(10):1029-33. DOI:10.1016/S1542-3565(05)00528-8 · 6.53 Impact Factor
  • Gastrointestinal Endoscopy 04/2005; 61(5). DOI:10.1016/S0016-5107(05)01475-6 · 4.90 Impact Factor
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    ABSTRACT: EUS is an important modality for the diagnosis of pancreatic disease. An understanding of normal pancreatic ductal and parenchymal variation in asymptomatic individuals is essential to improve EUS accuracy. The primary aim of this study was to determine age-related pancreatic parenchymal and ductular changes identifiable on EUS in individuals with no history or symptoms of pancreaticobiliary disease. Secondary aims were to define demographic and clinical factors associated with identifiable pancreatic parenchymal and ductular changes, and to determine the main pancreatic-duct diameter and pancreatic-gland width according to age. Patients referred for either upper endoscopy or EUS for an indication unrelated to pancreaticobiliary disease were prospectively enrolled. Patients were stratified by age (<40, 40-60, >60 years). Each patient was assessed for the presence of EUS findings for chronic pancreatitis. Logistic regression was used to identify factors associated with an abnormality. A total of 120 patients (63 men, 57 women; median age, 52 years, interquartile range [IQR] 40-61 years) were prospectively evaluated. At least one parenchymal and/or ductular abnormality was identified in 28% of the patients, with a trend of increasing abnormality with age: <40 years (23%), 40 to 60 years (25%), and >60 years (39%); p = 0.13. No patient had more than 3 abnormal EUS features. Hyperechoic stranding (n = 22) was the most common finding in all age groups. The odds for any abnormality in men (relative to women) was significantly higher (OR 2.9: 95% CI[1.2, 6.8], p = 0.01), with 38% of men and 18% of women having an abnormality. Smoking, low alcohol intake, body mass index, and endoscopic finding were not significantly associated with an abnormal EUS. The overall median pancreatic-gland width and main pancreatic duct diameter were 15 mm (IQR 6-25 mm) and 1.7 mm (IQR 0.9-4.3 mm), respectively. The frequency of EUS abnormalities in patients without clinical evidence of chronic pancreatitis increases with age, particularly after 60 years of age. The threshold number of EUS criteria for the diagnosis of chronic pancreatitis is variable. However, the typically used standard of 3 or more criteria appears appropriate. A higher number of threshold criteria may be needed in males and to a lesser extent in patients over 40 years of age, which should be related to clinical history and other structural or functional studies. Ductal or parenchymal calculi, ductal narrowing, ductal dilatation, or more than 3 abnormalities appear to be more specific features for the EUS diagnosis of chronic pancreatitis at any age.
    Gastrointestinal Endoscopy 03/2005; 61(3):401-6. DOI:10.1016/S0016-5107(04)02758-0 · 4.90 Impact Factor
  • Gastrointestinal Endoscopy 04/2004; 59(5). DOI:10.1016/S0016-5107(04)00535-8 · 4.90 Impact Factor
  • Gastrointestinal Endoscopy 04/2004; 59(5). DOI:10.1016/S0016-5107(04)00548-6 · 4.90 Impact Factor
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    ABSTRACT: Therapy of esophageal carcinoma is stage dependent. The role of EUS-guided fine-needle aspiration (EUS FNA) in this setting is unclear. The aims of this study were to compare the performance characteristics of CT, EUS, and EUS FNA for preoperative nodal staging of esophageal carcinoma and to measure the impact of each staging test on treatment decisions. From December 1999 to March 2001, all patients with esophageal carcinoma seen at the Mayo Clinic Rochester were prospectively evaluated with CT, EUS, and EUS FNA. The impact of tumor stage on final therapy was assessed. A total of 125 patients with esophageal carcinoma were enrolled. EUS FNA was more sensitive (83% vs. 29%; P < 0.001) than CT and more accurate than CT (87% vs. 51%; P < 0.001) or EUS (87% vs. 74%; P = 0.012) for nodal staging. Direct surgical resection was contraindicated in 77% of patients evaluated due to advanced locoregional/metastatic disease. Tumor location, patient age, comorbidities, and tumor stage determined by CT, EUS, and EUS FNA were associated with treatment decisions (P < 0.05). EUS FNA resulting in a higher/worse stage than CT (41 patients) was associated with a greater rate of treatments that were not direct surgeries compared with cases in which the stage was the same or better. EUS FNA is more accurate for nodal staging and impacts on therapy of patients with esophageal carcinoma. EUS FNA should be included in the preoperative staging algorithm of these patients.
    Gastroenterology 12/2003; 125(6):1626-35. DOI:10.1053/j.gastro.2003.08.036 · 13.93 Impact Factor
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    ABSTRACT: There are few data regarding the risk of bacteremia with EUS-guided FNA. This study prospectively evaluated the frequency of bacteremia and other infectious complications after EUS-guided FNA. Patients referred for EUS-guided FNA of the upper GI tract lesions were considered for enrollment. Patients were excluded if there was an indication for preprocedure administration of antibiotics based on ASGE guidelines, had taken antibiotics within the prior 7 days, or if they had a pancreatic cystic lesion. Blood cultures were obtained immediately before the procedure, after routine endoscopy/radial EUS, and 15 minutes after EUS-guided FNA. Fifty-two patients underwent EUS-guided FNA at 74 sites (mean 1.4 sites/patient) totaling 266 passes of the fine needle (mean 5.1 FNA/patient). Coagulase negative Staphylococcus was grown in cultures from 3 patients (5.8%; 95% CI [1%, 15%]) and was considered a contaminant. Three patients (5.8%; 95% CI [1%, 15%]) developed bacteremia: Streptococcus viridans (n = 2), unidentified gram-negative bacillus (n = 1). No signs or symptoms of infection developed in any patient. EUS-guided FNA of solid lesions in the upper GI tract should be considered a low-risk procedure for infectious complications that does not warrant prophylactic administration of antibiotics for prevention of bacterial endocarditis.
    Gastrointestinal Endoscopy 06/2003; 57(6):672-8. DOI:10.1067/mge.2003.204 · 4.90 Impact Factor
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    ABSTRACT: Preoperative differentiation of benign and malignant/potentially malignant pancreatic cystic lesions is problematic. Data to support the role of EUS and EUS-guided fine-needle aspiration (EUS-FNA) are limited. This study assessed the sensitivity, specificity, and accuracy of EUS, cytopathology, and analysis of cyst fluid for pancreatic cystic lesions. Retrospectively, 111 consecutive patients were identified (54 men, 57 women; mean age 59 years, range 18-79 years) who underwent EUS from July 1997 to September 2000 because of known or suspected pancreatic cystic lesions based on CT or transabdominal US. Thirty-four patients (16 men, 18 women; mean age 55 years, 25-79 years) who underwent surgery formed the basis for this analysis. EUS diagnosis was compared with surgical pathology. Selected patients underwent EUS-FNA to obtain specimens for cytopathologic analysis and for determination of carcinoembryonic antigen levels. Based on surgical pathology, cysts were classified as benign (simple cyst, pseudocyst, serous cystadenoma) or malignant/potentially malignant (mucinous cystadenoma, intraductal papillary mucinous tumor, cystic islet cell tumor, cystic adenocarcinoma). EUS-FNA with cytopathologic assessment of cyst fluid was performed for 18 of the 34 patients; carcinoembryonic antigen level was determined in 11 cases. For EUS, cytopathology, and carcinoembryonic antigen, sensitivity was, respectively, 91%, (p = 0.01 vs. cytology), 27%, and 28%; specificity was, respectively, 60%, 100%, and 25%; and, accuracy was, respectively, 82%, 55%, and 27%. The sensitivity of EUS in all 13 patients with cystic islet cell tumor, intraductal papillary mucinous tumor, or cystic adenocarcinoma was 100%. Combining EUS, cytopathology, and carcinoembryonic antigen results did not improve accuracy. There were no complications related to the EUS or EUS-FNA. EUS alone is sensitive and accurate in identifying malignant/potentially malignant pancreatic cystic lesions. EUS-FNA to obtain specimens for cytopathologic analysis and determination of carcinoembryonic antigen levels, although safe, does not enhance diagnostic yield.
    Gastrointestinal Endoscopy 11/2002; 56(4):543-7. DOI:10.1067/mge.2002.128106 · 4.90 Impact Factor
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    ABSTRACT: Before endoscopic mucosal resection and polypectomy of sessile lesions, injection of fluid into the submucosa cushions and isolates the tissue and thereby reduces thermal injury and the risk for perforation and hemorrhage. This study investigated the performance of 5 different solutions when used to form submucosal fluid cushions in the porcine esophagus. Five groups of 5 pigs were studied. In each pig, 6 separate submucosal injections of 5 mL of a single test solution were performed within the distal third of the esophagus. The time required for the submucosal bleb to flatten completely was recorded after each injection. The solutions used were as follows: normal saline solution, normal saline plus epinephrine solution, 50% dextrose, 10% glycerine/5% fructose in normal saline solution, and 1% rooster comb hyaluronic acid. The normal saline solution and normal saline plus epinephrine solutions had the shortest disappearance times (respectively, median 2.4 and 3.0 minutes), which were significantly shorter compared with the other test solutions. The mean disappearance times for 50% dextrose and 10% glycerine were, respectively, 4.7 and 4.2 minutes. The mean disappearance time for hyaluronic acid was 22.1 minutes. A solution of hyaluronic acid appears to be ideal for producing a lasting submucosal cushion for prolonged procedures. Dextrose 50% is superior to normal saline solution and may serve as an alternative to hyaluronic acid in terms of availability and cost.
    Gastrointestinal Endoscopy 11/2002; 56(4):513-6. DOI:10.1067/mge.2002.128107 · 4.90 Impact Factor
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    ABSTRACT: Existing EUS catheter probes have limited depth of penetration and lack color flow and Doppler capabilities. This study prospectively assessed the feasibility and safety of using a phased vector array US catheter in the human GI tract. Eleven patients underwent EUS with a steerable 9F phased vector array catheter. Images obtained with the catheter were compared with standard EUS images. The GI wall layers were equally well imaged with the catheter compared with standard echoendoscopes in 90% of the cases. Images of the liver, spleen, pancreatic parenchyma, and pancreatic duct were of equal quality and resolution with both techniques in the majority of patients. Some deeper structures and blood vessels were better visualized with the catheter. No complications were encountered. The steerable phased vector array US catheter is a safe device when used in the GI tract and offers images comparable with those obtained with a dedicated echoendoscope. Further studies are needed to determine the accuracy of tumor staging and clinical utility of this device.
    Gastrointestinal Endoscopy 10/2002; 56(3):430-5. DOI:10.1067/mge.2002.127102 · 4.90 Impact Factor
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    ABSTRACT: Cholangiography and tissue sampling (brush cytology, biopsy) are the standard nonsurgical techniques for determining whether a bile duct stricture is benign or malignant. The aim of this study was to determine whether intraductal US is of assistance in distinguishing benign from malignant biliary strictures. A retrospective review was undertaken of 30 patients with indeterminate bile duct strictures who underwent ERCP and tissue sampling from September 1999 to November 2000. A 20 MHz over-the-guidewire intraductal US catheter probe was used during ERCP for further examination of the strictures. Final diagnoses of malignant strictures (18 patients) were confirmed histopathologically; confirmation of benign stricture (12 patients) was based on negative tissue sampling plus extended clinical follow-up. Based on retrospective blinded review, the diagnosis by ERCP was correct in 67% of patients, by tissue sampling in 68%, by combined ERCP/tissue sampling in 67%, and by intraductal US in 90% (p = 0.04 vs. ERCP/tissue sampling) of cases. No complication of intraductal US or ERCP was recorded. Intraductal US is safe and can improve on the ability at ERCP to distinguish benign from malignant biliary strictures.
    Gastrointestinal Endoscopy 10/2002; 56(3):372-9. DOI:10.1016/S0016-5107(02)70041-2 · 4.90 Impact Factor
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    ABSTRACT: The optimal management of adenoma of the major duodenal papilla is not established. Options include surgical excision, endoscopic ablative techniques, snare excision, and observation with periodic biopsies. The aims of this retrospective study were to determine the safety and outcome of snare excision of the papilla. Twenty-eight snare excisions of the papilla were performed in 26 patients. Sixteen had familial adenomatous polyposis. In 22 procedures, a minisnare was used, and in 6 cases a prototype snare was designed for excision of the papilla. Pancreatic stents were placed as a prophylactic measure at the discretion of the endoscopist (n = 10). Histopathologically, resected tissue included 25 adenomas, 1 inflammatory polyp, 1 invasive malignancy, and 1 normal papilla. Immediate complications were minor bleeding (n = 2), mild pancreatitis (n = 4) and a duodenal perforation (n = 1). The presence (n = 10) or absence (n = 18) of a pancreatic stent did not correlate with subsequent pancreatitis (2 in each group, p = NS). Follow-up was available for 21 patients (median, 9 months; range, 2-32 months). Pancreatic duct stenosis at the papillectomy site resulted in pancreatitis in 2 patients (17%) at, respectively, 4 months and 24 months. Follow-up endoscopy revealed recurrent/residual adenomatous tissue in 2 (10%). Snare excision of the major duodenal papilla was well tolerated. Most complications were mild except for a small duodenal perforation. Stenosis of the pancreatic duct orifice with pancreatitis may be a late complication.
    Gastrointestinal Endoscopy 09/2002; 56(2):239-43. DOI:10.1067/mge.2002.126064 · 4.90 Impact Factor
  • The American Journal of Gastroenterology 09/2002; 97(9). DOI:10.1016/S0002-9270(02)05411-4 · 9.21 Impact Factor
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    ABSTRACT: Submucosal saline solution injection may limit the depth of thermal injury to the gut wall by acting as a heat-sink and by increasing the distance between burn and serosa. The aim of this study was to determine the effect of submucosal saline solution injection on depth of colonic thermal injury produced by commonly used endoscopic thermal modalities. Longitudinal colotomy incisions were made on the antimesenteric colonic border of anesthetized swine. Lesions were made by using a bipolar device (20 W, 2 seconds), heat probe (30 J); monopolar contact with hot biopsy forceps (20 W, 2 seconds), and monopolar noncontact with argon plasma coagulation (45 W, 3 seconds). Ten or more lesions were created with each device. Lesions were made with or without prior submucosal injection of 2 mL of normal saline solution. After 24 hours the lesions were excised for histologic analysis. Injury was assessed in relation to the severity of damage to the deep (longitudinal) muscle layer. The proportions of control lesions (without submucosal saline solution injection) in which deep injury was evident were as follows: argon plasma coagulation, 86%; hot biopsy forceps, 64%; heat probe, 50%; bipolar device, 18%. Submucosal saline solution injection significantly reduced the proportions of lesions with deep injury for argon plasma coagulation (p = 0.009) and heat probe (p = 0.03), but not hot biopsy forceps or bipolar device (argon plasma coagulation, 86% to 21%; heat probe, 50% to 0%; hot biopsy forceps, 64% to 50%; bipolar device, 18% to 9%). At equivalent energy outputs, the bipolar device results in less deep injury than the monopolar or heat probe. Submucosal saline solution injection reduced injury to the muscularis propria caused by both heat probe and argon plasma coagulation, but not hot biopsy forceps. Despite submucosal saline solution injection, caution should be exercised when using prolonged monopolar cautery.
    Gastrointestinal Endoscopy 08/2002; 56(1):95-9. DOI:10.1067/mge.2002.125362 · 4.90 Impact Factor
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    ABSTRACT: Endoluminal transmural resection of colorectal lesions is a pivotal advance in endoscopic technology. A full-thickness resection device has been developed that functions through a combination of tissue grasping, stapling, and cutting under endoscopic guidance. This preclinical study evaluated the performance, safety, and effectiveness of the full-thickness resection device in a porcine model. The full-thickness resection device consists of an operative handle, flexible shaft, and a resection chamber head. Eight pigs were randomized to 2 survival groups (4 each) of 14 and 28 days. The mucosa was marked electrosurgically to delineate target areas in the distal colon. A gastroscope inserted through the channel of the full-thickness resection device was advanced together with the device to the target. Targeted tissue was pulled into the resection chamber with a forceps, staples were deployed, and the isolated specimen was resected with a cutting blade. Histologic and radiographic evaluations were performed. All resections were transmural. Mean resected tissue diameter was 3.6 cm (1.4-5.2 cm). Mean procedure time was 30.2 (15) minutes. Minor mechanical problems required the use of replacement devices to complete 3 procedures. Resection sites were identified endoscopically and radiographically at sacrifice. In one animal, local adhesions were present. Histology evaluation disclosed resection line mucosal ulceration in 4 animals with fibroinflammatory changes consistent with healing. The full-thickness resection device can be used for endoluminal transmural localized resection of colorectal tissue in an animal model.
    Gastrointestinal Endoscopy 07/2002; 55(7):915-20. DOI:10.1067/mge.2002.124099 · 4.90 Impact Factor

Publication Stats

2k Citations
281.44 Total Impact Points


  • 1998–2007
    • Mayo Clinic - Rochester
      • • Department of Gastroenterology and Hepatology
      • • Department of Internal Medicine
      Rochester, Minnesota, United States
  • 2001–2005
    • University of Minnesota Rochester
      Rochester, Minnesota, United States
  • 2000
    • CRO Centro di Riferimento Oncologico di Aviano
      Aviano, Friuli Venezia Giulia, Italy