Biomedical subjects
Publications and source records attributed to A Chak.
Explore the source record for details and available documents.
BACKGROUND: Standard endosonographic (EUS) staging criteria are unreliable for staging esophageal carcinoma after neoadjuvant therapy; however, measurement of tumor size reduction can identify patients who have achieved a pathologic response. In the current study the authors prospectively compared survival between patients classified as responders and those classified as nonresponders by EUS. METHODS: The maximal transverse cross-sectional area of the tumor was measured before and after neoadjuvant therapy in patients who were candidates for multimodality treatment. Response was defined as a > or = 50% reduction in tumor area. RESULTS: A total of 59 patients at 2 centers were followed for a median of 19 months. EUS assessed response in 34 patients (58%). Overall, responders had a median survival of 17.6 months compared with 14.5 months for nonresponders (P < 0.005). Survival was significantly longer in responders compared with nonresponders in the patient subgroup who underwent surgical resection (19.7 months vs. 14.6 months; P < 0. 005), the patient subgroup with adenocarcinoma (21.4 months vs. 10.8 months; P < 0.005), and the patient subgroup initially classified as having T3N1 disease (17.6 months vs. 14.1 months; P < 0.05). Survival was not found to differ significantly between responders and nonresponders in the subgroup of patients with squamous cell carcinoma. EUS response was the only clinical variable that was associated with survival time in a multivariate analysis (relative hazard = 0.27; P < 0.005). CONCLUSIONS: Patients with esophageal carcinoma who respond to neoadjuvant treatment as identified by EUS measurement of reduction in tumor size have a significantly better prognosis than nonresponders.
Explore the source record for details and available documents.
BACKGROUND: Endoscopically applied methylene blue selectively stains specialized columnar epithelium in Barrett's esophagus. METHODS: The diagnostic yield and cost of cancer surveillance in patients with Barrett's esophagus using methylene blue-directed biopsies (MBDB) were compared with surveillance using a "jumbo" random biopsy technique in a prospective, sequential, controlled trial. Esophagogastroduodenoscopy was performed with either MBDB or random biopsy in a randomized sequence. The proportions of various types of epithelia in each biopsy were estimated and dysplasia was graded in a blinded fashion. RESULTS: Forty-three patients with short- (n = 8), limited- (n = 10), and long-segment (n = 25) Barrett's esophagus were studied. Using MBDB technique, the average number of biopsies obtained per patient was significantly lower and the proportion of specialized columnar epithelium in each specimen was significantly higher compared with random biopsy. Dysplasia or cancer was diagnosed in significantly more MBDB specimens (12% vs. 6%, p = 0.004). Despite fewer biopsies per patient using MBDB, dysplasia or cancer was diagnosed in significantly more patients (44% vs. 28%, p = 0.03) than by random biopsy technique. MBDB cost less and detected more cancers than random biopsy. CONCLUSIONS: MBDB is a more accurate and cost-effective technique than random biopsy for diagnosing specialized columnar epithelium and dysplasia/cancer, particularly in long-segment Barrett's esophagus.
BACKGROUND: Pancreaticobiliary strictures identified at endoscopic retrograde cholangiopancreatography (ERCP) can be evaluated by intraductal ultrasonography (US). Two major difficulties are that sphincterotomy may be required and the stricture may not be traversable. We prospectively evaluated the ease and success of intraductal US using a new over-the-wire catheter US probe. METHODS: Biliary or pancreatic strictures discovered at ERCP were imaged with the new probe. Intraductal US performance times, image clarity, imaging depth and technical ease were measured. RESULTS: Twenty-one patients with a variety of inflammatory and malignant pancreaticobiliary lesions were studied. Thirteen of the 16 (81%) masses imaged by intraductal US were 10 mm or less in diameter. Sphincterotomy was not required. All strictures traversed by a guidewire were imaged. The sphincter of Oddi was successfully imaged in all patients with intact normal sphincters. Performance of intraductal US was rated as technically easy in all cases and image clarity was rated as good or very good in 15 of 21 (71%) cases. CONCLUSIONS: The new over-the-wire catheter US probe facilitates intraductal US. Sphincterotomy is avoided and strictures are successfully traversed. This probe makes it possible to image the sphincter of Oddi.
BACKGROUND: Little is known about the accuracy of diagnostic and procedural codes for common gastrointestinal (GI) conditions and endoscopic procedures. METHODS: Eight hundred eighty-two patients with upper GI hemorrhage admitted in 1994 to 1 of 13 regional hospitals were studied. Based on endoscopy reports, the source of hemorrhage, performance of upper endoscopy and use of endoscopic therapy were determined, and we assessed the sensitivity and positive predictive value of discharge codes for measuring the source of hemorrhage and use of upper endoscopy. RESULTS: The sensitivity and positive predictive value of principal diagnosis coding for source of hemorrhage were typically 85% to 95%. The sensitivity and predictive value of coding for upper endoscopy were 97.7% and 99.9%, respectively, and were 72.3% and 99.4%, respectively, for endoscopic therapy. Accuracy did not differ between the 4 major teaching and 9 other hospitals. CONCLUSIONS: Hospital-based diagnostic and procedural codes are a reasonably accurate source of data for clinical and outcomes analyses of upper GI hemorrhage. In particular, it is possible to discern from these data the source of hemorrhage and the overall use of upper endoscopy.
BACKGROUND: Optical coherence tomography (OCT) has demonstrated the microscopic structure of the gastrointestinal (GI) tract mucosa and submucosa in vitro. We evaluated a prototype OCT system and assessed the feasibility of OCT in the human GI tract. METHODS: The 2.4 mm diameter prototype OCT probe, inserted through an endoscope, provides a 360-degree radial scan. Images (6.7 frames/sec) are displayed on a television monitor. Tissue contact is not required. In patients undergoing elective endoscopy, OCT images were obtained of normal mucosa (confirmed by biopsy). RESULTS: Seventy-two sites were imaged (38 patients): esophagus (21), stomach (12), duodenum (11), terminal ileum (4), colon (15), and rectum (9). Varying the distance between the probe and the mucosal surface produced images of the GI wall of varying depth. When held about 1 mm above the mucosal surface, the images consisted of mucosal structures such as colonic crypts, gastric pits, and duodenal villi. With the probe held against the wall, the OCT image comprised several layers interpreted as mucosa, muscularis mucosae, and submucosa. Structures including blood vessels were evident within the submucosa. A probe with a 0.5 mm working distance to the focal point provided the best images. Reducing the frame rate to 4.0 per second facilitated image interpretation. CONCLUSIONS: OCT is feasible in the human GI tract and provides interpretable high-resolution images of mucosa and submucosa.
Endosonography is primarily a diagnostic imaging modality, but new therapeutic applications are being developed. Miniprobe technology (ultrasound catheter probes) has led to new clinical applications. The staging of gastrointestinal cancers remains the major accepted indication for endosonography. Other conditions, such as chronic pancreatitis, portal hypertension, and inflammatory bowel diseases, are also being evaluated with endosonographic imaging.
BACKGROUND: Endoscopic examinations of the colon are often recommended for surveillance following colorectal cancer resection. The actual use and outcome of this testing are not known. METHODS: Five thousand seven hundred sixteen patients 65 years of age or older with local or regional stage colorectal cancer diagnosed in 1991 were identified through the Surveillance Epidemiology and End Results registry. All inpatient and outpatient Medicare claims from 6 months after diagnosis through the end of 1994 were examined to determine use of endoscopic procedures. RESULTS: One or more colonoscopies were performed in 51%, with an average of 2.9 procedures performed among those tested; sigmoidoscopy was performed in 17%. The rate of colonoscopy was highest during the initial 18 months. Polypectomy was performed in 21% of all patients, and subsequent primary colorectal tumors were diagnosed in 1.3%. Factors associated with colonoscopy and sigmoidoscopy use included younger age, survival through follow-up, and geographic region; sigmoidoscopy was also more common in relation to rectal cancers. CONCLUSIONS: There is variability in the use of endoscopic procedures following potentially curative resection for colorectal cancer, with patient-related factors and local practice patterns accounting for the variation. Further studies are needed to elicit the reasons for lack of follow-up and adherence to practice guidelines.
BACKGROUND: Recurrent bleeding after successful primary endoscopic hemostasis of acutely bleeding ulcers is a significant problem. This study evaluates endoscopic Doppler ultrasound (US) in assessing risk of recurrent bleeding in patients presenting with acute peptic ulcer hemorrhage. METHODS: In this prospective, double-blind, nonrandomized trial, patients were enrolled from a single academic institution. Only patients with endoscopically confirmed gastric, duodenal, pyloric, or anastomotic ulcers were enrolled. The therapeutic endoscopist was blinded to the Doppler US signal from the ulcer and based treatment decisions on standard guidelines. A 16 MHz pulsed-wave, linear scanning, US probe was used through the accessory channel of an endoscope to assess for the presence of a Doppler signal. RESULTS: Fifty-two of 139 screened patients entered the trial (55 Doppler sessions). Endoscopic therapy was performed in 42% (30-day recurrent bleeding rate of 17%). Ulcers that remained persistently Doppler positive immediately after endoscopic therapy had a significantly higher rate of recurrent bleeding than ulcers where the Doppler signal was abolished: 100% versus 11% (p = 0.003). There were no bleeding-related deaths. CONCLUSIONS: A persistently positive Doppler US signal appears to be a marker of inadequate endoscopic therapy in patients with acutely bleeding peptic ulcers.
BACKGROUND: Although experts have demonstrated the efficacy of endoscopic retrograde cholangiopancreatography (ERCP) in cholangitis, the effectiveness of ERCP in unselected patients has not been measured. The aim was to investigate the clinical impact of ERCP performed at any time and of early ERCP (within 24 hours of admission) in patients with a primary discharge diagnosis of cholangitis. METHODS: A retrospective record review of patients admitted to eight area hospitals with an International Classification of Diseases (ICD)-9 diagnosis consistent with cholangitis was performed. Extracted data included clinical characteristics, ERCP findings, and patient outcome. The associations of ERCP overall and early ERCP with length of stay were examined. Confounding factors including severity of illness, etiology of cholangitis, and hospital type were adjusted for in a multivariate analysis. RESULTS: A total of 116 patients were studied. ERCP was performed in 71 patients with endoscopic therapy administered in 57 (80%). ERCP overall was not associated with any change in length of hospital stay. However, compared with other invasive biliary procedures, ERCP was associated with a shorter hospital stay (median 5 vs. 9.5 days, p = 0.01) and a 36% (95% CI [5%, 57%]) reduction in severity-adjusted length of stay. Patients who had early ERCP had a significantly shorter hospital stay than those who had delayed ERCP (median 4 vs. 7 days, p < 0.005) and early ERCP was associated with a 34% (95% CI [11%, 48%]) reduction in severity-adjusted length of stay. CONCLUSION: Early ERCP may be an effective strategy for shortening the length of stay in patients hospitalized with cholangitis.
Explore the source record for details and available documents.
BACKGROUND: There are a paucity of data supporting the routine use of follow-up testing to detect recurrent disease after potentially curative initial surgery in patients with nonmetastatic colorectal carcinoma. METHODS: Using the population-based Surveillance, Epidemiology, and End Results (SEER) registry, all patients age > or =65 years with local or regional colorectal carcinoma who were diagnosed in 1991, underwent surgical resection, and survived at least 6 months after diagnosis were identified. All inpatient, hospital outpatient, and physician/supplier Medicare claims from 6 months after diagnosis through 1994 were examined for follow-up procedures of interest. Procedure use during follow-up was compared across patient groups using both bivariate and multivariate analyses. RESULTS: A total of 5716 patients were identified, with 1.3% found to have developed subsequent primary tumors of the colon or rectum, and 74% surviving through 1994. One or more procedures of interest were performed in 88% of patients; the most commonly performed tests were liver enzymes, chest X-rays, colonoscopy, and computed tomography scans. Lower rates of testing generally were observed with older age groups, patients with fewer comorbidities, and patients who did not survive through the follow-up period. Among all procedures studied, there also was significant variation in the rates of testing across the 9 SEER areas, varying from 1.5-fold to 3.6-fold. The geographic variation persisted in multivariate models adjusting for potentially confounding factors. CONCLUSIONS: The current study found significant variability in the use of follow-up procedures, with the most striking differences apparent across geographic regions. Further studies are needed to determine the underlying reasons for the disparities, as well as the impact of surveillance on patient outcomes.
BACKGROUND: Open access endoscopy systems (those in which endoscopy is performed without prior gastroenterology consultation) are becoming more common in the current cost-conscious environment. The aim of this study was to compare appropriateness and yield of endoscopy for patients referred for open access endoscopy with those for patients who had prior contact with a gastroenterologist. We also evaluated patients' preference for undergoing open access endoscopy as opposed to having prior consultation with a gastroenterologist and compared preparedness for endoscopic procedures between the two groups. METHODS: The cases of all outpatients referred for upper endoscopy and colonoscopy were assessed prospectively over a 5-month period. American Society for Gastrointestinal Endoscopy (ASGE) guidelines for indications for gastrointestinal endoscopy were used to determine appropriateness of referrals. Significant pathologic findings were rated independently by two investigators using defined criteria. Patients' opinions regarding preparedness for endoscopy and referral preference were measured by means of questionnaires administered before endoscopy. RESULTS: Eighty-six percent of endoscopies after consultation with gastroenterologists were performed for accepted indications compared with 65% of open access procedures (p < 0.01). Significant pathologic findings were present in 40% of the former group compared with 28% of those undergoing open access endoscopy (p < 0.01). Significant pathologic findings were found in 37% of endoscopies performed for indications listed in the ASGE guidelines compared with 20% for unlisted indications (p < 0.01). Forty percent of patients referred for open access endoscopy would have preferred prior consultation with a gastroenterologist. CONCLUSION: Patients initially seen by a gastroenterologist are more likely to undergo endoscopy for accepted indications, and the yield of endoscopy is higher than among patients referred through an open access system. The system of open access endoscopy as currently practiced may have to be reassessed.
BACKGROUND: The aim of this study was to determine the safety, efficacy, and accuracy of endoscopic ultrasound (EUS)-guided fine-needle aspiration using the GF-UM30P echoendoscope. METHODS: GF-UM30P-guided EUS-guided fine-needle aspiration results from 3 EUS referral centers were prospectively recorded. Successful sampling required that the needle tip be seen within the lesion on at least 1 pass. Aspirates were considered adequate if they were diagnostic for cancer, contained suspicious or atypical cells, or were adequately cellular for interpretation but nondiagnostic. RESULTS: EUS-guided fine-needle aspiration was attempted on 162 lesions in 152 patients with no complications. Sampling was successful in 150 of 162 (93%) attempts (mean lesion size 2.5 +/- 1.2 cm (range 0.7 to 6.0 cm). Aspirates were adequately cellular in 138 of 162 (85%) attempts (43% diagnostic, 15% suspicious and/or atypical cells, 27% adequate cellularity but nondiagnostic). Sampling failed in 12 of 162 (7%) attempts. Ten of 12 (83%) failures and 11 of 12 (92%) inadequate aspirates occurred when lesions measured less than 2 cm. The sensitivity for malignancy was 93% if only successfully sampled lesions with surgically confirmed negative results were included. However, it was 68% if all attempts were included and when unconfirmed high/moderate suspicion negative results were counted as false negatives and low suspicion negative results as true negatives. CONCLUSIONS: The GF-UM30P may be clinically useful for EUS-guided fine-needle aspiration if a curved linear array instrument is unavailable.
BACKGROUND: Limitations in the technical capabilities of the fiberoptic echoendoscope often necessitate concurrent diagnostic endoscopy at the time of an endosonographic (EUS) examination. Our aim was to determine whether a new video echoendoscope would allow the performance of EUS without diagnostic endoscopy. METHODS: EUS examinations on all patients at two centers were initiated with a fiberoptic echoendoscope (period of 5 weeks) or a video echoendoscope (period of 6 weeks). Note was made of need for concurrent diagnostic endoscopy. The endosonographer also rated the mechanical, optical, and sonographic performance of the video instrument using a 9-point comparative scale (1 = much worse, 5 = equal to, and 9 = much better than fiberoptic echoendoscope). RESULTS: A total of 103 patients including 40 and 28 with mural lesions and 22 and 15 with retroperitoneal lesions were examined with the fiberoptic and video echoendoscopes, respectively. Mean values for parameters rating the video echoendoscope's mechanical performance ranged between 5.0 and 5.9, optical performance ranged between 6.6 and 7.5, and sonographic performance ranged between 4.6 and 4.9. Concurrent diagnostic endoscopy was required less frequently when patients with mural lesions (18% vs. 70%, p < 0.005) or patients with retroperitoneal lesions (0% vs. 14%, p = no significance) were examined with the video echoendoscope compared with the fiberoptic echoendoscope. CONCLUSIONS: Moderately improved optics and slightly better mechanical characteristics of the new video echoendoscope allow the performance of EUS without concurrent diagnostic endoscopy in the majority of patients.
BACKGROUND: Recent guidelines indicate that colonoscopy and sigmoidoscopy are both acceptable options for screening average-risk patients for colorectal cancer. Retrospective studies have found that a majority of patients with cancer proximal to the splenic flexure have a normal screening flexible sigmoidoscopy. METHODS: This was a multicenter, prospective description of colonoscopic findings and family history in consecutive patients with proximal colon cancer. RESULTS: Among 116 prospectively identified average-risk patients with cancer proximal to the splenic flexure, 40 (34.5%) had neoplasia distal to the splenic flexure. The prevalence of patients with adenomas greater than or equal to 1 cm, with only one tubular adenoma less than 1 cm, and with only hyperplastic polyps were 16.4%, 8.6%, and 6.9%, respectively. CONCLUSIONS: Most average-risk patients with cancer proximal to the splenic flexure will have a normal screening flexible sigmoidoscopy. These patients have an unexpectedly high prevalence of large distal adenomas, but the prevalence of both single small tubular adenomas and hyperplastic polyps alone is similar to that expected during screening of the general population. Clinicians and payers should continue to seek methods to improve the cost-effectiveness and availability of screening colonoscopy in average-risk persons.
BACKGROUND: Use of an echocolonoscope to examine patients with inflammatory bowel disease is technically difficult. Catheter probe assisted endoluminal ultrasonography (US) may be a feasible alternative. METHODS: Determination of demographic information and clinical disease activity was followed by colonoscopy with biopsy. Catheter probe assisted endoluminal US was performed with measurements of thickness of the intestinal wall and evaluation of the structure of the sonographic layers. RESULTS: Twenty-eight patients, 7 with ulcerative colitis, 11 with Crohn's disease, and 10 healthy control subjects participated in a prospective study. Mean colonic wall thickness was 2.2 +/- 0.1 mm (controls) compared with 4. 1 +/- 0.4 mm (ulcerative colitis) (p < 0.001) and 4.4 +/- 0.4 mm (Crohn's disease) (p < 0.001). Among patients with ulcerative colitis, colonic wall thickness correlated with severity of colonoscopic changes (r = 0.84, p = 0.02). Among patients with Crohn's disease, loss of endosonographic layer structure correlated with disease activity score (r = 0.8, p = 0.003), and colonic wall thickness correlated with the severity of histologic changes (r = 0. 62, p = 0.04). CONCLUSIONS: Catheter probe assisted endoluminal US is technically feasible in the care of patients with inflammatory bowel disease. Endosonographic measurements of colonic wall thickness and layer structure provide clinically significant information.