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Biomedical subjects

Michael B Wallace

Publications and source records attributed to Michael B Wallace.

At least 19 recordsLinked to original sources
PubMed2007

Safety and efficacy of cytology brushings versus standard FNA in evaluating cystic lesions of the pancreas: a pilot study.

BACKGROUND: Cystic neoplastic lesions of the pancreas (CNLP) are increasingly detected and are associated with a potential for malignant transformation. Diagnostic assessment of these lesions is often limited by the cystic nature and focality of neoplastic progression of these lesions. EUS-guided FNA (EUS-FNA) of cyst fluid and exfoliated cells is one of the most accurate methods of diagnosis but still has limited sensitivity. A new, through-the-needle cytologic brush system has recently been approved for use during EUS evaluation of cystic lesions of the pancreas. OBJECTIVE: To evaluate the cytologic yield and safety profile of the new cytobrush compared with conventional FNA in evaluating CNLP. DESIGN: Ten consecutive patients with CNLP were included. All cysts were sampled by standard EUS-FNA (0.5 of cyst volume) followed by brush cytology, then by aspiration of the remaining fluid. Fluid samples were separately submitted (standard FNA and cytobrushings FNA) but were read by the same pathologist. Complications were assessed during the immediate postprocedure period (2-3 hours) and by a telephone call conducted approximately 30 days after the procedure to inquire about any new symptoms, including abdominal pain, melena, hematochezia, hematemesis, fever, nausea, and vomiting. SETTING: High-volume EUS referral center. PATIENTS: Ten consecutive patients with CNLP that measured at least 20 mm in maximal dimension were included. MAIN OUTCOME MEASUREMENTS: Cellularity and presence of diagnostic cells on the FNA. RESULTS: In 7 of 10 cases, the EchoBrush specimen was superior to FNA in terms of cellularity and detection of diagnostic cells. Two cases had complications: 1 major and 1 minor intracystic bleed. No infection or pancreatitis was observed. LIMITATIONS: The interpreting pathologist for the case was not blinded to the results of either of the samples. In addition, this pilot study represents only a single-center experience. CONCLUSIONS: This study suggests that brush cytology specimens obtained at the time of EUS are superior to conventional FNA because of the higher yield of epithelial cells. It is unclear whether bleeding is more common after EchoBrush sampling; however, caution should be taken in patients who require anticoagulation until further data are available.

Aged↗
PubMed2007

Accuracy of endoscopic ultrasonography and magnetic resonance cholangiopancreatography for the diagnosis of chronic pancreatitis: a prospective comparison study.

BACKGROUND: The diagnosis of chronic pancreatitis (CP) remains challenging. Endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) have been proposed as highly accurate diagnostic modalities. Although endoscopic retrograde cholangiopancreatography (ERCP) has been previously used as a gold standard, it is associated with a small but significant risk. We aim to compare the accuracy of EUS and MRCP with the composite gold standard using ERCP, surgical pathology, and/or long-term clinical follow-up. METHODS: Ninety-nine patients with clinical signs and/or symptoms suggestive of CP were prospectively enrolled. The diagnosis of CP by MRCP was established when one or more of these features were present: main duct dilation without obstruction, dilated side branches, intraductal stones, ductal irregularity, reduced T1-signal intensity, parenchymal atrophy, and reduced secretory response to secretin administration. The diagnosis of CP by EUS was made when 4 or more of the established criteria were present. Accuracy of all criteria used ("EUS only," "MRCP only," "either EUS or MRCP," and "both EUS and MRCP") was compared with the composite gold standard. RESULTS: Forty patients were diagnosed with CP by the composite gold standard whereas the remaining 59 patients were controls. EUS only seemed more sensitive but equally specific compared with MRCP only to diagnose CP. The combination of EUS and MRCP had a sensitivity of 98% for either EUS or MRCP and a specificity of 100% for both EUS and MRCP. CONCLUSIONS: EUS and MRCP are highly accurate modalities for the diagnosis of CP and are complementary when used together. If confirmed in larger series, the diagnosis of CP by both EUS and MRCP is highly predictive and ERCP is unlikely to add any useful information.

Adult↗
PubMed2006

Do cytokine concentrations in pancreatic juice predict the presence of pancreatic diseases?

BACKGROUND & AIMS: Cytokine concentration in pancreatic juice of patients with pancreatic disease is unknown. Secretin stimulation allows endoscopic collection of pancreatic juice secreted into the duodenum. We aimed to evaluate the cytokine concentrations in pancreatic juice of patients with abdominal pain to discriminate presence from absence of pancreatic disease. METHODS: From January 2003-December 2004, consecutive patients with abdominal pain compatible with pancreatic origin were enrolled. Patients underwent upper endoscopy. Intravenous secretin (0.2 mug/kg) was given immediately before scope intubation. Pancreatic juice collected from the duodenum was immediately snap-frozen in liquid nitrogen until assays were performed. Pancreatic juice levels of interleukin-8, interleukin-6, intercellular adhesion molecule 1, and transforming growth factor-beta 1 were measured by modified enzyme-linked immunosorbent assays. The final diagnosis was made by the primary gastroenterologist on the basis of medical history; laboratory, endoscopic, and imaging studies; and clinical follow-up. Fisher exact test and Kruskal-Wallis rank sum test were used for statistical analysis. RESULTS: Of 130 patients screened, 118 met the inclusion criteria. Multivariate analysis revealed that only interleukin-8 was able to discriminate between normal pancreas and chronic pancreatitis (P = .011), pancreatic cancer (P = .044), and the presence of pancreatic diseases (P = .007). Individual cytokine concentrations were not significantly different in chronic pancreatitis compared with pancreatic cancer. CONCLUSIONS: Cytokine levels can be measured in pancreatic juice obtained from the duodenum without direct cannulation of the pancreatic duct. Interleukin-8 concentration in pancreatic juice can be used to discriminate between normal pancreas and patients with pancreatic disease. This is a relatively simple and noninvasive method to aid in the diagnosis of pancreatic diseases.

Abdominal Pain↗
PubMed2006

Advanced imaging and technology in gastrointestinal neoplasia: summary of the AGA-NCI Symposium October 4-5, 2004.

Imaging and other advanced technologies for detection of gastrointestinal cancers are undergoing a major revolution on several fronts. This is facilitated by convergence of key technologies including advanced endoscopic-detection systems, more specific contrast agents, rapid and high-resolution cross-sectional imaging, and miniaturization of construction systems for making all imaging equipment smaller and less invasive. This convergence is occurring along traditional translational research pathways (clinical medicine-molecular biology) as well as nontraditional lines (clinical medicine-optical physics/engineering and molecular biology-optical physics/engineering). These new efforts are producing a wide array of technologies aimed at improving detection, classification, and monitoring of gastrointestinal neoplasia, especially for colorectal and esophageal cancer because of easier accessibility. A critical goal is to detect lesions at their premalignant stages, thereby permitting meaningful intervention. Inspired by these advances, the American Gastroenterological Association and the National Cancer Institute sponsored a symposium held in Bethesda, MD, from October 4-5, 2004, bringing together leading investigators with diverse backgrounds in imaging technology. The aims of this symposium were to summarize the state of the art and priorities for research in the coming decade in the field of imaging and advanced technology for gastrointestinal neoplasia. In this overview, we summarize the salient results of that symposium. The initial sections discuss the major technologies in each area of endoluminal imaging and molecular imaging followed by applications to specific diseases such as Barrett's esophagus and colon neoplasia. Each section focuses on the current state of the art then lists major priorities for research in the field.

Barrett Esophagus↗
PubMed2006

Enhanced magnification-directed biopsies do not increase the detection of intestinal metaplasia in patients with GERD.

BACKGROUND: The diagnosis of Barrett's esophagus (BE) requires histologic confirmation of specialized intestinal metaplasia (SIM) through biopsy, a technique prone to sampling error. One method designed to improve the yield of biopsy uses acetic acid with magnification endoscopy: enhanced magnification endoscopy (EME). This technique identifies several mucosal surface patterns, and of these, pattern types III and IV have been associated with SIM. METHODS: We conducted a prospective, randomized trial to compare EME-directed biopsies and standard endoscopy with random biopsies in patients with symptoms of gastroesophageal reflux disease. Patients in the standard endoscopy group with evidence of BE had four-quadrant random biopsies taken every 2 cm. If there was no BE, four-quadrant biopsies were taken at the SCJ. Patients in the EME group had the mucosa at the SCJ classified as type I-IV based on published criteria. Biopsies targeted to type III and IV were compared to random biopsies. RESULTS: One hundred thirty-seven patients enrolled (68 randomized to EME, 69 to standard endoscopy). Fifty-six (41%) had endoscopic evidence of BE (20 standard endoscopy [29%] vs 36 EME [53%]). Of the patients with apparent BE, standard endoscopy with random biopsies confirmed SIM in 12 (60%) compared to 11 of 18 (61%) patients with EME targeted biopsies of patterns type III or IV (p = 1.0). Patients without apparent BE (N = 81) had SIM of the SCJ confirmed in 16% (8 of 49) with standard endoscopy and random biopsies compared with 8% (1 of 12) using EME-directed biopsy of pattern III or IV (p = 0.67). CONCLUSIONS: Random biopsies of endoscopically apparent BE and a normal SCJ yield SIM at the same rate as targeted biopsies with EME in patients with pattern types III or IV. This calls into question the utility of this technique in reducing sampling error to identify SIM.

Barrett Esophagus↗
PubMed2006

Hold on Picasso, narrow band imaging is here.

The goal of colonoscopy is to identify and remove premalignant and malignant polyps. During colonoscopy it is not feasible to differentiate with certainty if a polyp is benign or premalignant, resulting in removal of all polyps via polypectomy. In attempts to overcome this clinical dilemma, techniques such as chromendoscopy have been developed to aid in improving the accuracy of identifying precancerous polyps. Chromendoscopy helps detect suspicious polyps using a dye spraying technique, but it is time consuming and causes collateral distortion of the adjacent mucosal field. Recently, narrow band imaging (NBI) has been able to highlight abnormal mucosal topography and microvasculature by illuminating with narrow range blue light. This is achieved with the click of a button on the endoscope, and the accuracy of differentiating between abnormal and normal mucosa is equivalent to chromendoscopy. NBI and other similar technologies will likely provide an electronic, easier alternative to chromoendoscopy to aid the endoscopist in differentiation among benign, premalignant, and malignant mucosal patterns.

Colonic Polyps↗
PubMed2005

Is zinc concentration in pancreatic fluid a marker for pancreatic diseases?

OBJECTIVES: An imbalance of free radicals and scavenging processes has been implicated in the pathogenesis of pancreatic tissue injury. Gradual decreases in antioxidant enzyme expression in pancreatic cells from normal pancreas to chronic pancreatitis to pancreatic cancer have been reported. Zinc is one of the components of antioxidant enzymes and may play a role in the pathogenesis of pancreatic diseases. A recent report showed a significant decrease in pancreatic zinc output in patients with chronic pancreatitis and proposed that zinc output can be used as an alternative to enzyme output for the diagnosis. We aimed to determine the zinc concentration in pancreatic fluid of patients with chronic pancreatitis and pancreatic cancer compared to normal pancreas. PATIENTS: Seventy-five consecutive patients were prospectively evaluated. Chronic pancreatitis was diagnosed in 20 patients by ERCP (n=16) and histology (n=4). Pancreatic cancer was diagnosed in 17 patients by cytology from EUS-FNA (n=12) or surgical pathology (n=5). Thirty-eight patients were confirmed to have normal pancreas. INTERVENTIONS: Patients underwent esophagogastroduodenoscopy following intravenous secretin injection (0.2 microg/kg). Pancreatic fluid collected for 10 minutes was immediately frozen at -80 degrees C and stored until the assay was performed. MAIN OUTCOME MEASURE: Zinc concentrations were determined by inductively coupled plasma optical emission spectroscopy. RESULTS: Among the three groups, patients with pancreatic cancer were significant older (P<0.001) with a higher prevalence of diabetes mellitus (P=0.002). Gender distribution (P=0.098), body mass index (P=0.925), and history of alcohol use (P=0.997) were similar among groups. Zinc concentrations in pancreatic fluid were not significantly different among groups (P=0.129). CONCLUSIONS: Zinc concentration in pancreatic fluid was comparable in patients with chronic pancreatitis and pancreatic cancer compared to normal pancreas. Zinc concentration in pancreatic fluid collected by our 10-minute endoscopic method cannot reliably be used for the diagnosis of chronic pancreatitis and/or pancreatic cancer.

Acute Disease↗