Gastrointestinal endoscopy: past and future

The former editor of Gastrointestinal Endoscopy reflects on the history of endoscopy, which reveals much about the mechanisms whereby innovation occurred, and attempts to forecast the future. Endoscopic technological development in most industrialised countries will be determined largely by various combinations of many external factors together with the further development of virtual imaging.

Familial aggregation of Barrett's oesophagus, oesophageal adenocarcinoma, and oesophagogastric junctional adenocarcinoma in Caucasian adults

BACKGROUND

Although familial clusters of Barrett's oesophagus and oesophageal adenocarcinoma have been reported, a familial predisposition to these diseases has not been systematically investigated.

AIMS

To determine whether Barrett's oesophagus and oesophageal (or oesophagogastric junctional) adenocarcinoma aggregate in families.

PATIENTS AND METHODS

A structured questionnaire eliciting details on reflux symptoms, exposure history, and family history was given to Caucasian case (n=58) subjects with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma, and to Caucasian control (n=106) subjects with symptomatic gastro-oesophageal reflux disease without Barrett's oesophagus. Reported diagnoses of family members were confirmed by review of medical records.

RESULTS

The presence of a positive family history (that is, first or second degree relative with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma) was significantly higher among case subjects compared with controls (24% v 5%; p<0.005). Case subjects were more likely to be older (p<0.001) and male (74% v 43% male; p<0.0005) compared with control subjects. In a multivariate logistic regression analysis, family history was independently associated with the presence of Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma (odds ratio 12.23, 95% confidence interval 3.34-44.76) after adjusting for age, sex, and the presence of obesity 10 or more years prior to study enrollment.

CONCLUSIONS

Individuals with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma are more likely to have a positive family history of Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma than individuals without Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma. A positive family history should be considered when making decisions about screening endoscopy in patients with symptoms of gastro-oesophageal reflux.

Evaluation of a rapid urine amylase test using post-ERCP hyperamylasemia as a model

OBJECTIVE

The initial diagnosis of acute pancreatitis is often based on clinical criteria together with elevations of serum amylase and lipase. A reliable bedside urine test could facilitate the early diagnosis of pancreatitis. We evaluated a rapid urine amylase test (Rapignost) by using post-ERCP hyperamylasemia as a human model of acute development of hyperamylasemia suggestive of pancreatitis.

METHODS

Seventy-five patients undergoing ERCP were prospectively evaluated. Patients with renal insufficiency, hyperlipidemia, or hyperglycemia were excluded. Before ERCP, patients had serum amylase and lipase measured, and urine amylase tested with the Rapignost test strip. At 4 and 16-24 h post-ERCP, a serum and urine (test strip) amylase were measured again; the adequacy of urine collection was verified by measuring a 2-h creatinine clearance. Patients were clinically assessed for the development of clinical pancreatitis. The concordance of the strip result with post-ERCP hyperamylasemia was assessed.

RESULTS

The sensitivity of the test strip for the detection of hyperamylasemia was greatest at 16-24 h post-ERCP (78%). Specificity was uniformally high (100% specificity at 16-24 h post-procedure). The test strip was positive in all cases of clinical pancreatitis. Of three cases of clinically evident ERCP-induced pancreatitis, only one was urine test strip positive by 4 h post-procedure.

CONCLUSIONS

Using post-ERCP hyperamylasemia as a model, the Rapignost rapid urine amylase test strip was only marginally sensitive but highly specific for hyperamylasemia. The urine test strip was positive in all cases of clinical pancreatitis and may be a useful bedside test for the diagnosis of acute pancreatitis.

High-resolution endoscopic imaging of the GI tract: a comparative study of optical coherence tomography versus high-frequency catheter probe EUS

BACKGROUND

Both optical coherence tomography (OCT) and catheter probe EUS (CPEUS) are candidates for high-resolution imaging of the GI wall, but their potential roles in this clinical context have not been investigated.

METHODS

OCT and CPEUS were used to image normal-appearing portions of the GI tract at the same sites. CPEUS was performed with a 20-MHz or a new 30-MHz catheter probe.

RESULTS

Forty-four histologically confirmed normal sites in 27 patients were evaluated. With OCT, mucosa and muscularis mucosa were clearly seen at all sites. Except for stomach, OCT demonstrated the submucosa in all sites. OCT penetration ranged from 0.7 to 0.9 mm. Microscopic structures such as esophageal glands, intestinal villi, colonic crypts, and blood vessels were easily identified. CPEUS penetration ranged from 10 mm to 20 mm, and 5 to 7 distinct layers were discernible. However, both mucosa and submucosa were seen as thin layers without microscopic detail.

CONCLUSION

OCT resolution is superior to high-frequency CPEUS, but depth of penetration is limited to mucosa and submucosa. OCT images the major structural components of the mucosa and submucosa whereas CPEUS does not. Potentially, OCT and high-frequency CPEUS may be complementary for clinical imaging.

Wire-guided intraductal US: an adjunct to ERCP in the management of bile duct stones

BACKGROUND

Endoscopic retrograde cholangiography (ERC) may misdiagnose bile duct stones if air bubbles are introduced during contrast injection, and it may also fail to diagnose stones in the presence of bile duct dilation.

METHODS

Our aim was to determine whether intraductal US (IDUS) improves the accuracy of cholangiography and whether it is a useful adjunct in the management of bile duct stones. IDUS with a wire-guided US probe was performed after initial ERC in patients in whom bile duct stones were suspected. The diagnostic accuracy of ERC alone was compared with that of ERC plus IDUS.

RESULTS

ERC with IDUS was performed in 62 patients who were suspected to have bile duct stones. Both IDUS and ERC were performed by the same endoscopist, and ERC was performed with a C-arm fluoroscope. The presence of bile duct stones and/or sludge were confirmed after sphincterotomy and extraction in 34 patients. Overall, the accuracy of ERC combined with IDUS in the diagnosis of bile duct stone and/or sludge was higher than that of ERC alone (97% vs. 87%, p < 0.05). With dilated bile ducts, the diagnostic accuracy of ERC combined with IDUS was also higher than that of ERC alone (95.5% vs. 72.7%, p < 0.05). Additional diagnostic information provided by IDUS included identification of cystic duct stones in 5 patients, characterization of bile duct strictures in 2 patients, and choledochal varices in 1 patient. Performance of wire-guided IDUS required 5% of the total procedure time.

CONCLUSIONS

IDUS improves diagnostic accuracy of ERC and is a useful adjunct to ERC when bile duct stones are suspected.

Prospective evaluation of balloon-sheathed catheter US system

BACKGROUND

Catheter US probes must rely on luminal water to create images because they do not incorporate a water-filled balloon such as that used with a designated echoendoscope. The purpose of this study is to determine the effectiveness and safety of a balloon sheath for the US catheter system.

METHODS

Catheter EUS was performed on 50 patients by using a 2.3 mm 12 MHz or 20 MHz catheter probe. Catheter EUS was used in 47 cases, and a newly developed water-filled balloon sheath was used in 41 cases. Both devices were used in 39 cases. Procedure time, depth of ultrasound penetration, and a subjective assessment of image quality and ease of use were recorded, along with TMN stage as applicable. Catheter EUS findings were confirmed with a standard radial scanning echoendoscopy (S-EUS) in 18 cases.

RESULTS

Catheter probe EUS (C-EUS) and catheter probe plus balloon (CB-EUS) imaging was obtained of 25 esophageal, 8 gastric, 4 rectal, 1 biliary, and 1 duodenal lesion. Time required for the ultrasound portion of the examination was identical with C-EUS and CB-EUS. Depth of penetration increased with CB-EUS with both the 12 MHz and 20 MHz probes (p < 0.05). Subjective assessment of image clarity improved when CB-EUS was used in the esophagus. C-EUS failed to identify 2 esophageal cancers and 2 sets of paraesophageal lymph nodes, and understaged 1 esophageal cancer. The remaining 14 cancers were staged identically by both modalities. The catheter probes with and without the balloon sheath were easy to use, even in markedly narrow esophageal strictures. CB-EUS did not significantly improve resolution in the stomach or rectum. S-EUS confirmed findings of CB-EUS in all 18 cases in which both instruments were used. There were no procedure-related complications.

CONCLUSIONS

For esophageal lesions, CB-EUS improves images compared with C-EUS, and enhances depth of penetration without prolonging or encumbering the examination. CB-EUS offers no advantage over C-EUS in organs other than the esophagus. S-EUS, when possible, remains the preferred imaging modality for esophageal cancers because of the ability to image the celiac axis and other deep structures.

Cervical esophageal perforation during EUS: a national survey

BACKGROUND

EUS is considered to be as safe a procedure as EGD. However, the longer, rigid tip of the echoendoscopes raises concern about cervical esophageal perforation during intubation. Our aim was to determine the rate of this complication.

METHODS

Members of the American Endosonography Club were surveyed by questionnaire to determine the number of EUS examinations performed and the number of cervical esophageal perforations encountered up to June 1999. Each questionnaire was coded to avoid duplicate reporting.

RESULTS

Questionnaires were mailed to 203 members; 86 (42.4%) responded. Cervical esophageal perforation occurred in 16 of 43,852 reported upper EUS procedures at a frequency of 0.03%. Fifteen (94%) patients were elderly. A history of difficult intubation with prior endoscopic procedures was present in 7 (44%) patients. Three patients had large cervical osteophytes. In 9 (56%) patients, the procedure was done by an endosonographer with less than 1 year of experience. Two patients required surgery. One patient died as a result of the perforation and the other 13 (81%) patients were managed successfully with conservative treatment.

CONCLUSIONS

The incidence of cervical perforation during upper EUS may be higher than during EGD. Advanced patient age, difficult intubation during prior upper endoscopy, operator inexperience, and the presence of large cervical osteophytes may contribute to cervical perforation during upper EUS examination.

Methylene blue staining of dysplastic and nondysplastic Barrett's esophagus: an in vivo and ex vivo study

BACKGROUND AND STUDY AIMS

Methylene blue selectively stains specialized columnar epithelium in Barrett's esophagus with high accuracy. We prospectively evaluated the methylene blue staining properties of dysplastic and nondysplastic Barrett's esophagus and the association of these properties with the risk for dysplasia and cancer.

PATIENTS AND METHODS

In a ex vivo study, we mapped, photographed, and sampled esophagectomy specimens with high grade dysplasia and/or early adenocarcinoma before and after methylene blue staining. In a concurrent in vivo study, we performed methylene blue staining and characterized methylene blue stain characteristics. Pathologists estimated the proportion of specialized columnar epithelium in each specimen and graded dysplasia.

RESULTS

We examined 551 biopsies from 47 patients with biopsy-proven Barrett's esophagus and 48 sections from five surgical specimens with Barrett's esophagus and dysplasia and early adenocarcinoma. The accuracy of ex vivo and in vivo methylene blue staining for specialized columnar epithelium was 87% and 90%, respectively. It was influenced by the length of Barrett's esophagus, biopsy location, and the presence of esophagitis and/or dysplasia. Light to absent staining (p = 0.01) and moderate to marked heterogeneity (p = 0.01) were significantly associated with high grade dysplasia or cancer in the univariate analysis and in a multivariate model that adjusted for the length of Barrett's esophagus and the presence of a lesion. These staining characteristics were present in all patients with severe dysplasia and/or adenocarcinoma.

CONCLUSIONS

Highly dysplastic or malignant Barrett's esophagus stains differently with methylene blue. Increased heterogeneity and decreased methylene blue stain intensity are significant independent predictors of high grade dysplasia and/or cancer. These features may help to direct biopsies in patients without a lesion.

Potential new endoscopic techniques for the earlier diagnosis of pre-malignancy

Light interacts with tissue in a variety of ways, including absorption, fluorescence, elastic scattering and Raman scattering. These interactions enable a number of promising technologies for endoscopic diagnosis of pre-malignancy, including chromoscopy; fluorescence, scattering and Raman spectroscopies; and optical coherence tomography. Although still in various stages of technical development and clinical trials, these optical diagnostic techniques are demonstrating strong potential to significantly enhance the clinical endoscopist's ability to detect dysplasia in gastrointestinal mucosae.

Preliminary evaluation of the prototype stereoscopic endoscope: precise three-dimensional measurement system

A prototype stereoscopic endoscope (incorporating two charged-coupled devices), developed for the accurate three-dimensional measurement of gastrointestinal tract lesions, was initially evaluated with two-dimensional target grids and in vitro measurement of 15 objects of known size (marbles, cubes, and rectangular prisms) placed in a plastic model of the sigmoid colon. Images of the objects were captured and stored in a computer. Stereoscopic measurements were compared with results from the standard (open biopsy forceps) method by a blinded endoscopist. The volume measured with the stereoscope did not differ significantly from the true volume, whereas the volume obtained with the open biopsy forceps method differed significantly from the actual volume, consistently underestimating the actual size. The aberration ratios (percentage deviation between the measured and true volume, expressed as mean +/- SD) obtained with the stereoscopic endoscope were superior (9.2% +/- 9.5%) to those obtained with the open biopsy forceps method (-34.0% +/- 26.8%). These preliminary in vitro results with the stereoscope show considerable promise for the simple and precise three-dimensional measurement of gastrointestinal lesions and warrant human clinical trials.

Endosonography in the evaluation of patients with Barrett's esophagus and high-grade dysplasia

Endosonography, which provides high-resolution images of the esophageal wall, could potentially detect carcinoma not visible endoscopically in patients with Barrett's esophagus and high-grade dysplasia. We studied the ability of endosonography to detect early esophageal carcinoma in 9 patients with Barrett's esophagus and high-grade dysplasia who were candidates for esophagectomy. Pre-operative endoscopy and biopsy revealed high-grade dysplasia without evidence of carcinoma in all patients. Pre-operative endosonographic evaluations were compared to the pathologic diagnoses of resected specimens. Post-operatively, 3 of the 9 patients were found to have intra-mucosal carcinoma. Endosonography identified a tumor in only 1 of these 3 patients and over-staged it as invasive carcinoma (T2, N1). In 2 of the 6 patients without intra-mucosal carcinoma, endosonography predicted invasive carcinoma (T2, N0). Endoscopy revealed mucosal nodularity in each of the 3 over-staged patients. We conclude that recommendation of the routine use of endosonography to determine the need for surgery in patients with Barrett's esophagus and high-grade dysplasia would be premature, because the current generation of echo-endoscopes does not reliably differentiate between benign and malignant wall thickening.

Gastrointestinal tissue diagnosis by laser-induced fluorescence spectroscopy at endoscopy

An endoscope-compatible, optical fiber system has been developed which can be used to obtain laser-induced fluorescence spectra of mucosal abnormalities during endoscopy in real time. The results of our previous in vitro studies have suggested that laser-induced fluorescence tissue spectra are sufficiently unique that they can be used to accurately diagnose mucosal abnormalities in some systems. To test this hypothesis in vivo, laser-induced fluorescence spectra were obtained during colonoscopy from 31 colonic adenomas, 4 hyperplastic polyps, and 32 examples of normal mucosa in 20 patients. The resulting spectra could be used to correctly differentiate adenomas from normal colonic mucosa and hyperplastic polyps in 97% of the specimens studied with the resulting sensitivity, specificity, and positive predictive value of 100%, 97%, and 94%, respectively. These results, although preliminary in nature, suggest that laser-induced fluorescence spectra can be used in the recognition and differential diagnosis of mucosal abnormalities at endoscopy.

Endoscopic ultrasound in the pre-operative staging of rectal carcinoma

Endoscopic ultrasound (EUS) was performed prospectively to stage 45 patients with rectal cancer. Patients were staged utilizing the TNM staging system. All patients subsequently underwent surgical resection with independent histopathologic staging. Depth of invasion was accurately predicted in 40 of 45 patients (89%). Presence or absence of lymph node metastasis was correctly determined in 34 of 45 patients (79%). EUS is an accurate method for local staging of rectal cancer.

Endoscopic ultrasonography in the differential diagnosis of pancreatic disease

Endoscopic ultrasonography was performed in 25 patients with suspected pancreatic disease. Cancer of the pancreas was recognized in 9 of 10 cases with 1 false negative and 2 false positive diagnoses. Chronic pancreatitis was recognized in 89% of cases. Technical difficulties limited the success of the examination in 24% of cases. The presence or absence of pancreatic disease can be determined in most cases by endoscopic ultrasonography. Differential diagnosis by endoscopic ultrasonography (EUS) is correct in the majority of cases. We have not discovered any specific EUS finding(s) that are pathognomonic for pancreatic cancer or chronic pancreatitis.

Endosonographic features predictive of lymph node metastasis

Endosonographic features that are thought to characterize lymph node metastasis were evaluated in 100 patients with esophageal carcinoma. Subjects underwent preoperative endoscopic ultrasonography to assess depth of tumor invasion (T stage) and lymph node metastasis (N stage). Endosonographically imaged lymph nodes were evaluated according to the following parameters: size, shape, border demarcation, and central echo pattern. Sensitivity and specificity of endosonography in detecting lymph node metastasis were 89.1% and 91.7%, respectively, when stringent criteria were used. When lymph nodes were imaged endosonographically, regardless of the specific features, the likelihood of N1 disease, was 86%, whereas when no lymph nodes were imaged, the chance of N0 disease was 79%. Endosonographic features predictive of malignancy in increasing order of importance were echo-poor (hypoechoic) structure, sharply demarcated borders, rounded contour, and size greater than 10 mm. Collectively, the EUS features produced an additive effect with respect to accuracy in the prediction of malignant lymph node involvement; malignancy could be predicted with 100% accuracy when all four features were present. These results demonstrate that a careful and systematic approach to the endosonographic assessment of lymph node metastasis can improve staging accuracy.

Evaluation of submucosal upper gastrointestinal tract lesions by endoscopic ultrasound

The proper diagnosis of submucosal upper gastrointestinal tract mass lesions by endoscopy or barium study is difficult. Differentiation between submucosal tumors, vascular structures, and extrinsic organs is often impossible. We performed endoscopic ultrasound examination of 91 patients with upper gastrointestinal submucosal mass lesions. Endoscopic ultrasound was accurate in determining the site of origin in 48 of 50 cases where pathology or angiography comparison was available. Leiomyoma, lipoma, varices, and carcinoma had characteristic ultrasonographic findings. Endoscopic ultrasound is a useful procedure in the evaluation of upper gastrointestinal submucosal mass lesions.

Endoscopic ultrasonography in the diagnosis of pancreatic tumors

Endoscopic ultrasonography (EUS) can provide high resolution images of the pancreatic parenchyma. Complete visualization of the pancreas requires scanning from positions in the duodenum and stomach. Current clinical experience indicates that EUS is a useful adjunct to standard imaging in the evaluation of suspected pancreatic tumors. Improvements in technique and instruments are necessary to broaden the clinical application of EUS in pancreatic disease.

Role of Doppler US in acute peptic ulcer hemorrhage: can it predict failure of endoscopic therapy?

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.

Endoscopic palliation for inoperable pancreatic cancer

BACKGROUND

The majority of patients with pancreatic cancer are not candidates for surgical resection. Palliative therapy remains the cornerstone of management of this population.

METHODS

We reviewed recent clinical and experimental studies on endoscopic palliative therapy of inoperable pancreatic cancer.

RESULTS

Endoscopic placement of a biliary stent is the preferred mode of palliation of obstructive jaundice in patients with pancreatic cancer. The techniques of endoscopic stent insertion are briefly described. Episodic recurrence of jaundice and cholangitis due to stent occlusion is a major drawback of biliary polyethylene stents. Self-expandable metal stents with large diameters have lower rates of stent occlusion and are cost effective in patients who are expected to survive beyond 3 months. Palliation of duodenal obstruction with self-expandable enteral stents and endosonography-guided celiac plexus neurolysis are emerging options for the treatment of patients with advanced pancreatic cancer.

CONCLUSIONS

Endoscopic therapy offers safe and effective management options for palliation of major symptoms associated with inoperable pancreatic cancer.

Methylene blue-directed biopsies improve detection of intestinal metaplasia and dysplasia in Barrett's esophagus

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.

Endosonographic assessment of multimodality therapy predicts survival of esophageal carcinoma patients

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.

High-resolution endoscopic imaging of the GI tract using optical coherence tomography

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.

Prospective evaluation of an over-the-wire catheter US probe

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.

A multicenter U.S. experience with EUS-guided fine-needle aspiration using the Olympus GF-UM30P echoendoscope: safety and effectiveness

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.

Real-time in vivo imaging of human gastrointestinal ultrastructure by use of endoscopic optical coherence tomography with a novel efficient interferometer design

We report on the design and initial clinical experience with a real-time endoscopic optical coherence tomography (EOCT) imaging system. The EOCT unit includes a high-speed optical coherence tomography interferometer, endoscope-compatible catheter probes, and real-time data capture and display hardware and software. Several technological innovations are introduced that improve EOCT efficiency and performance. In initial clinical studies using the EOCT system, the esophagus, stomach, duodenum, ileum, colon, and rectum of patients with normal endoscopic findings were examined. In these initial investigations, EOCT imaging clearly delineated the substructure of the mucosa and submucosa in several gastrointestinal organs; microscopic structures such as glands, blood vessels, pits, villi, and crypts were also observed.