Search PubMed⌕ Search

Biomedical subjects

J Van Dam

Publications and source records attributed to J Van Dam.

At least 37 records · Page 2Linked to original sources
PubMed2000

Advances in diagnostic and therapeutic endoscopy.

Endoscopy is extremely valuable in the evaluation of disorders of the luminal gastrointestinal tract, pancreas, and biliary system. Endoscopy as a medical discipline continues to evolve and is becoming increasingly therapeutic in nature. Minimally invasive endoscopic intervention now is effective in a wide variety of disorders, including gastrointestinal hemorrhage, obstructive diseases of the intestinal or biliary tree, and early detection or prevention of neoplastic disease of the colon and esophagus. The development of EUS technology has expanded greatly the potential utility of endoscopy as a diagnostic and a therapeutic modality, and further technologic advances are anticipated.

Bile Duct Diseases↗
PubMed2000

Endoscopic detection of dysplasia in patients with Barrett's esophagus using light-scattering spectroscopy.

BACKGROUND & AIMS: We conducted a study to assess the potential of light-scattering spectroscopy (LSS), which can measure epithelial nuclear enlargement and crowding, for in situ detection of dysplasia in patients with Barrett's esophagus. METHODS: Consecutive patients with suspected Barrett's esophagus underwent endoscopy and systematic biopsy. Before biopsy, each site was sampled by LSS using a fiberoptic probe. Diffusely reflected white light was spectrally analyzed to obtain the size distribution of cell nuclei in the mucosal layer, from which the percentage of enlarged nuclei and the degree of crowding were determined. Dysplasia was assigned if more than 30% of the nuclei exceeded 10 microm and the histologic findings compared with those of 4 pathologists blinded to the light-scattering assessment. The data were then retrospectively analyzed to further explore the diagnostic potential of LSS. RESULTS: Seventy-six sites from 13 patients were sampled. All abnormal sites and a random sample of nondysplastic sites were reviewed by the pathologists. The average diagnoses were 4 sites from 4 different patients as high-grade dysplasia (HGD), 8 sites from 5 different patients as low-grade dysplasia (LGD), 12 as indefinite for dysplasia, and 52 as nondysplastic Barrett's. The sensitivity and specificity of LSS for detecting dysplasia (either LGD or HGD) were 90% and 90%, respectively, with all HGD and 87% of LGD sites correctly classified. Decision algorithms using both nuclear enlargement and crowding further improved diagnostic accuracy, and accurately classified samples into the 4 histologic categories. CONCLUSIONS: LSS can reliably detect LGD and HGD in patients with Barrett's esophagus.

Aged↗
PubMed2000

Optical coherence tomography: advanced technology for the endoscopic imaging of Barrett's esophagus.

BACKGROUND AND STUDY AIMS: Endoscopic optical coherence tomography (OCT) is an emerging medical technology capable of generating high-resolution cross-sectional imaging of tissue microstructure in situ and in real time. We assess the use and feasibility of OCT for real-time screening and diagnosis of Barrett's esophagus, and also review state-of-the-art OCT technology for endoscopic imaging. MATERIALS AND METHODS: OCT imaging was performed as an adjunct to endoscopic imaging of the human esophagus. Real-time OCT (13-microm resolution) was used to perform image-guided evaluation of normal esophagus and Barrett's esophagus. Beam delivery was accomplished with a 1-mm diameter OCT catheter-probe that can be introduced into the accessory channel of a standard endoscope. Different catheter-probe imaging designs which performed linear and radial scanning were assessed. Novel ultrahigh-resolution (1.1-microm resolution) and spectroscopic OCT techniques were used to image in vitro specimens of Barrett's esophagus. RESULTS: Endoscopic OCT images revealed distinct layers of normal human esophagus extending from the epithelium to the muscularis propria. In contrast, the presence of gland- and crypt-like morphologies and the absence of layered structures were observed in Barrett's esophagus. All OCT images showed strong correlations with architectural morphology in histological findings. Ultrahigh-resolution OCT techniques achieved 1.1-microm image resolution in in vitro specimens and showed enhanced resolution of architectural features. Spectroscopic OCT identified localized regions of wavelength-dependent optical scattering, enhancing the differentiation of Barrett's esophagus. CONCLUSIONS: OCT technology with compact fiberoptic imaging probes can be used as an adjunct to endoscopy for real-time image-guided evaluation of Barrett's esophagus. Linear and radial scan patterns have different advantages and limitations depending upon the application. Ultrahigh-resolution and spectroscopic OCT techniques improve structural tissue recognition and suggest future potential for resolution and contrast enhancements in clinical studies. A new balloon catheter-probe delivery device is proposed for systematic imaging and screening of the esophagus.

Barrett Esophagus↗
PubMed2000

Enhanced gastrointestinal diagnosis: light-scattering spectroscopy and optical coherence tomography.

Detection of microscopic and biochemical changes within the mucosa and submucosa are beyond the realm of routine endoscopy. Distinguishing hyperplastic from neoplastic polyps, differentiating malignant from benign ulcers, and detecting mucosal dysplasia in patients with ulcerative colitis or Barrett's esophagus remain within the purview of the gastrointestinal pathologist. Recent developments in tissue spectroscopy and endoscopic optical coherence tomography have the potential to expand significantly our ability to diagnose gastrointestinal disease beyond the capabilities of visible light endoscopy.

Barrett Esophagus↗
PubMed1999

Pretreatment staging by endoscopic ultrasonography does not predict complete response to neoadjuvant chemoradiation in patients with esophageal carcinoma.

BACKGROUND: Endoscopic ultrasonography (EUS) provides highly accurate preoperative T and N classifications in patients with esophageal carcinoma. Although previous data have suggested that patients with tumors classified as T4 by EUS do not benefit from surgical resection, these data were acquired prior to the widespread use of preoperative chemoradiation. The current study investigated whether pretreatment EUS can predict a complete response to neoadjuvant therapy. METHODS: Patients with esophageal carcinoma (adenocarcinoma or squamous cell carcinoma) underwent EUS classification prior to therapy. Patients classified as T2, T3, or T4 and M0 were treated with 5-fluorouracil, cisplatin, and radiation under protocol. Patients with T1 lesions underwent resection without prior chemoradiation. Chemoradiation was followed in all cases by attempted surgical resection. The initial EUS classification was compared with the final pathologic results. RESULTS: Fifty-five patients (47 males and 8 females) with a mean age of 60.5 years (range, 31-78 years) were evaluated. There were 41 adenocarcinomas and 14 squamous cell carcinomas. Among the total population, a complete response was achieved in 3 of 5 patients (60%) with tumors classified as T2 by EUS, 14 of 42 patients (33%) with tumors classified as T3 by EUS, and 5 of 8 patients (63%) with tumors classified as T4 by EUS (P = 0.19). A complete response was achieved in 9 of 24 patients (38%) found to have N0 disease by EUS versus 13 of 30 patients (43%) determined to have N1 disease (P = 0.66). The results for patients with adenocarcinoma and squamous cell carcinoma were similar. CONCLUSIONS: The results of the current study demonstrate that pretreatment EUS does not predict reliably which patients with esophageal carcinoma will achieve a complete pathologic response to preoperative neoadjuvant chemoradiation.

Adenocarcinoma↗
PubMed1999

Accuracy and complication rate of brush cytology from bile duct versus pancreatic duct.

BACKGROUND: The accuracy and complication rates of brush cytology obtained from pancreaticobiliary strictures have not been fully defined. In this study we compared the accuracy and complications of brush cytology obtained from bile versus pancreatic ducts. METHODS: We identified 148 consecutive patients for whom brush cytology was done during an ERCP from a database with prospectively collected data. We compared cytology results with the final diagnosis as determined by surgical pathologic examination or long-term clinical follow-up. We followed all patients and recorded ERCP-related complications. RESULTS: Forty-two pancreatic brush cytology samples and 101 biliary brush cytology samples were obtained. The accuracy rate of biliary cytology was 65 of 101 (64.3%) and the accuracy rate of pancreatic cytology was 30 of 42 (71.4%). Overall sensitivity was 50% for biliary cytology and 58.3% for pancreatic cytology. Of 67 patients with pancreatic adenocarcinoma, sensitivity for biliary cytology was 50% versus 66% for pancreatic cytology. Concurrent pancreatic and biliary cytology during the same procedure increased the sensitivity in only 1 of 10 (10%) patients. Pancreatitis occurred in 11 (11%) patients (9 mild cases, 2 moderate cases) after biliary cytology and in 9 (21%) patients (6 mild cases, 3 moderate cases) after pancreatic cytology (p = 0.22). In 10 patients who had pancreatic brush cytology, a pancreatic stent was placed. None of these patients developed pancreatitis versus 9 of 32 (28%) patients in whom a stent was not placed (p = 0.08). Pancreatic cytology samples obtained from the head of the pancreas were correct in 13 of 18 (72%) cases, from the genu in 7 of 7 (100%) cases, from the body in 5 of 9 (55%) cases, and from the tail in 4 of 7 (57%) cases. CONCLUSION: The accuracy of biliary brush cytology is similar to the accuracy of pancreatic brush cytology. The yield of the latter for pancreatic adenocarcinoma is similar to that of the former. Complication rates for pancreatic cytology are not significantly higher than the rates for biliary cytology. The placement of a pancreatic stent after pancreatic brushing appears to reduce the risk of postprocedure pancreatitis.

Adenocarcinoma↗
PubMed1999

In vivo identification of colonic dysplasia using fluorescence endoscopic imaging.

BACKGROUND: Previous in vitro studies showed that autofluorescence images of colonic mucosa collected endoscopically can be used to detect dysplasia with high sensitivity. This method is extended to the collection of fluorescence images of adenomatous polyps in vivo. METHODS: Fluorescence images were collected during colonoscopy in 30 patients. A total of 12 adenomatous and 6 hyperplastic polyps were identified. A fiberoptic excitation probe, located in the instrument channel of the colonoscope, delivered 300 mW of near-ultraviolet light at lambdaex = 351 and 364 nm. Mucosal fluorescence in the spectral bandwidth between 400 and 700 nm was imaged, processed, and displayed with various likelihoods of associated dysplasia. RESULTS: Adenomatous polyps exhibited decreased fluorescence intensity compared with adjacent mucosa with normal appearance. With the fluorescence threshold set to 80% of the average intensity of normal mucosa, a sensitivity of 83% for dysplasia identification was achieved. All hyperplastic polyps were correctly identified as being non-dysplastic. Optimal identification of dysplastic regions was obtained with the colonoscope oriented at a near-normal angle of incidence to the polyps. At higher angles of incidence, artifacts caused by illumination shadows were introduced. CONCLUSIONS: The dysplasia associated with adenomatous polyps can be identified in vivo by fluorescence imaging with high sensitivity, thus demonstrating the potential to guide endoscopic procurement of biopsy specimens.

Adenomatous Polyps↗
PubMed1999

Prospective comparative evaluation of video US endoscope.

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.

Adult↗
PubMed1999

Increased rate of complete EUS staging of patients with esophageal cancer using the nonoptical, wire-guided echoendoscope.

BACKGROUND: Incomplete endoscopic ultrasound (EUS) staging procedures in patients with esophageal cancer due to obstructing malignant strictures are prone to underestimate T stage and cannot detect celiac adenopathy. EUS staging in the setting of stenotic malignancies using the large caliber echoendoscope has been complicated by esophageal perforation. We report on the clinical utility of a newly developed, wire-guided echoendoscope for the complete staging of patients with esophageal cancer. METHODS: Pretreatment EUS examinations performed for esophageal cancer staging were evaluated and the ability to traverse the esophagus and examine the celiac axis were documented. Outcomes before and after the availability of the wire-guided echoendoscope were compared. RESULTS: One hundred thirty consecutive examinations were evaluated 100 before and 30 after the introduction of the wire-guided echoendoscope. Complete staging was accomplished in 60 of 100 (60%) cases before and 27 of 30 (90%) after its introduction (p = 0.002). The wire-guided echoendoscope was used in 14 of the 30 cases. Despite a trend toward fewer stage T4 tumors, metastatic disease was documented significantly more frequently after the introduction of the esophagoprobe (34% vs. 11%, p = 0.002). There were no complications. CONCLUSIONS: The introduction of the wire-guided echoendoscope markedly reduced the occurrence of incomplete esophageal cancer staging and improved the detection of metastatic disease.

Adenocarcinoma↗