Clinical experience using a real time autofluorescence endoscopy system in the gastrointestinal tract

Autofluorescence spectra of neoplastic tissues have been reported to be significantly different from those of normal tissues when excited by blue or violet light. From this concept, a light-induced autofluorescence endoscopic imaging system for gastrointestinal mucosa (LIFE-GI; Xillix, Canada and Olympus, Japan) has been newly developed and the clinical evaluation of the prototype system has been conducted in hospitals in Canada, Netherlands and Japan.We examined the clinical usefulness of the prototype LIFE-GI system for the detection of gastrointestinal cancer and high and low grade dysplasia. The LIFE-GI system was also applied to the early detection of remnant lesions after endoscopic treatment of early gastric cancer and to the detection of laterally spreading superficial colonic tumors.This system has potential application for the diagnosis of dysplastic lesions and early cancers in the gastrointestinal tract as an adjunct to ordinary white light endoscopy. This system, which needs no administration of a photosensitive agent, may be suitable as a screening method for the early detection of neoplastic tissues.     

Development of the autofluorescence endoscope imaging system

It is a well known fact that light emitted at a specific wavelength induces fluorescence in the human body. This kind of fluorescence is called autofluorescence. The application of autofluorescence diagnosis, on the other hand, is a more complicated system designed to detect faint autofluorescence inherent in tissues/cells. We have adopted this autofluorescence diagnosis method and developed a new autofluorescence endoscope imaging system called the SAFE-1000. Normal mucosa emitting autofluorescence appears green on the monitor, while abnormal mucosa shows a dark image caused by the lack of autofluorescence.     

Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

We present the first endoscopic Doppler optical coherence tomography and co-registered autofluorescence imaging (DOCT-AFI) of peripheral pulmonary nodules and vascular networks in vivo using a small 0.9 mm diameter catheter. Using exemplary images from volumetric data sets collected from 31 patients during flexible bronchoscopy, we demonstrate how DOCT and AFI offer complementary information that may increase the ability to locate and characterize pulmonary nodules. AFI offers a sensitive visual presentation for the rapid identification of suspicious airway sites, while co-registered OCT provides detailed structural information to assess the airway morphology. We demonstrate the ability of AFI to visualize vascular networks in vivo and validate this finding using Doppler and structural OCT. Given the advantages of higher resolution, smaller probe size, and ability to visualize vasculature, DOCT-AFI has the potential to increase diagnostic accuracy and minimize bleeding to guide biopsy of pulmonary nodules compared to radial endobronchial ultrasound, the current standard of care.OCIS codes: (170.0170) Medical optics and biotechnology, (170.0110) Imaging systems, (170.4500) Optical coherence tomography, (170.2520) Fluorescence microscopy     

Endoscopic ultraviolet-induced autofluorescence spectroscopy of the esophagus: tissue characterization and potential for early cancer diagnosis

BACKGROUND AND STUDY AIMS: Endoscopic identification of dysplasia and early carcinoma of the esophagus is difficult and is currently done through random pinch biopsies. This study assesses the potential of ultraviolet-induced autofluorescence spectroscopy for early diagnosis with special focus on Barrett's esophagus. PATIENTS AND METHODS: Measurements were performed on 24 patients using 330 nm light excitation. The determination of the spectral distribution typical of each histological tissue type was done using three fluorescence intensity ratios: RI = I390nm/I450nm; R2 = I550nm/I450nm; R3 - I390nm/I550nm. RESULTS: The spectral distribution of normal esophageal mucosa and specialized columnar Barrett's mucosa were similar. A strong modification of the spectral distribution was observed for high grade dysplasia and intramucosal carcinoma. Statistical analysis indicated that the spectral shape modification associated with neoplastic transformation was greater than intra- and interpatient spectral variations. These results allow the determination of discriminating criteria based on ratios R1 and R3. Using ratio R3, the spectroscopy-based diagnosis differentiated neoplastic tissue from normal esophageal mucosa and specialized columnar Barrett's mucosa with a sensitivity and specificity of 86% and 95 %, respectively. CONCLUSIONS: The use of ultraviolet autofluorescence spectroscopy should improve the diagnostic yield of standard endoscopy in patients with Barrett's esophagus.     

Endoscopic gastroenteric anastomosis using magnets

BACKGROUND: Current management of malignant obstruction of the upper digestive tract includes surgical gastrointestinal bypass or endoscopic insertion of self-expandable metal stents. The safety, efficacy, and long-term patency rates of anastomoses created using the novel technique of endoscopic gastroenteric anastomosis using magnets (EGAM) are evaluated in this study. PATIENTS AND METHODS: 15 patients (13 men, 2 women; mean age 64.5 years) with malignant obstruction, who underwent EGAM and had monthly follow-up between December 2001 and May 2003, were included in this study. RESULTS: The procedure was successful in 13 patients (88.66 %). The mean survival was 5.23 months. There were four minor complications (30.76 %) during the follow-up period. CONCLUSION: Our results demonstrate the feasibility, safety. and efficacy of this technique for creating a gastroenteric anastomosis. The success rate was 86.6 %, there were no immediate complications, and there was no mortality related to the procedure.     

Endoscopic ultrasound-guided pancreatic duct aspiration: diagnostic yield and safety

BACKGROUND AND STUDY AIMS: Endoscopic ultrasound (EUS)-guided fine-needle aspiration provides useful diagnostic material in solid and cystic pancreatic lesions. It is logical that EUS-guided pancreatic duct aspiration may be useful in cases of suspected intraductal or duct-obstructing tumors. We evaluated the safety and efficacy of EUS-guided pancreatic duct aspiration. PATIENTS AND METHODS: Twelve patients with dilated pancreatic ducts underwent EUS-guided duct aspiration. Aspirates were submitted for cytology and mucin staining. Patients were followed for up to 13 months. RESULTS: There were no procedure-related complications. Cytology was diagnostic in nine of the 12 patients (six with intraductal papillary mucinous tumor, one with pancreatic clonorchiasis, and two with obstructing solid pancreatic adenocarcinomas). Cytology in the remaining three patients, all with solid obstructing masses, was nondiagnostic. Overall, the diagnostic yield was 75%; however, the yield was 100% in patients without extrinsic obstruction. CONCLUSION: This preliminary experience suggests that EUS-guided pancreatic duct aspiration is safe and can provide diagnostic material in a significant number of patients with unexplained pancreatic duct dilation.     

Feasibility of using multiphoton excited tissue autofluorescence for in vivo human histopathology

Rapid and direct imaging of microscopic tissue morphology and pathology can be achieved by multiphoton imaging of intrinsic tissue fluorophores and second harmonic signals. Engineering parameters for developing this technology for clinical applications include excitation levels and collection efficiencies required to obtain diagnostic quality images from different tissue types and whether these levels are mutagenic. Here we provide data on typical average powers required for high signal-to-noise in vivo tissue imaging and assess the risk potential of these irradiance levels using a mammalian cell gene mutation assay. Exposure times of ~16 milliseconds per cell to 760 nm, ~200 fs raster-scanned laser irradiation delivered through a 0.75 NA objective produced negligible mutagenicity at powers up to about 50 mW.     

Endoscopic therapy using double balloon endoscopy

Double balloon endoscopy (DBE) was developed as a new technique for visualization and intervention of the entire small intestine. It has been world-widely reported that DBE is very useful for not only diagnosis but also endoscopic therapy. In this chapter, hemostatic procedure, polypectomy, dilation therapy for benign strictures, reduction of intussusception, removal of foreign bodies, and therapeutic ERCP in long-limb surgical bypass patients are described introductively. Diagnostic DBE is thought to be safe with a low complication rate, but it is reported that the complication rate in therapeutic DBE is higher than that associated with colonoscopy. The thin wall of the small intestine can explain this. Endoscopic therapy in the small intestine should be performed with special care to avoid complications such as bleeding and perforation.     

A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

We present a power-efficient fiber-based imaging system capable of co-registered autofluorescence imaging and optical coherence tomography (AF/OCT). The system employs a custom fiber optic rotary joint (FORJ) with an embedded dichroic mirror to efficiently combine the OCT and AF pathways. This three-port wavelength multiplexing FORJ setup has a throughput of more than 83% for collected AF emission, significantly more efficient compared to previously reported fiber-based methods. A custom 900 µm diameter catheter ‒ consisting of a rotating lens assembly, double-clad fiber (DCF), and torque cable in a stationary plastic tube ‒ was fabricated to allow AF/OCT imaging of small airways in vivo. We demonstrate the performance of this system ex vivo in resected porcine airway specimens and in vivo in human on fingers, in the oral cavity, and in peripheral airways.OCIS codes: (110.0110) Imaging systems, (110.2350) Fiber optics imaging, (110.4500) Optical coherence tomography, (170.2520) Fluorescence microscopy, (170.3890) Medical optics instrumentation     

New incoherent autofluorescence/fluorescence system for early detection of lung cancer

A new autofluorescence (AF) system for bronchoscopy that operates as compact as a conventional white light bronchoscopy system is described. The system is also capable of white light illumination and excitation of aminolevulinic acid (ALA) induced fluorescence. Changing between white light and (auto-) fluorescence mode is easy and always possible. Broad band excitation with blue light (AF: 380-460 nm; ALA 380-440 nm) delivers high intensity illumination at the distal end of the bronchoscope (AF typically 50 mW). A special optical observation technique makes the AF directly visible to the eye instead of indirect techniques used in other AF systems. A compact (160 g)and sensitive (typically 0.2 lux) camera can be used for documentation.     

Endoscopic fine-needle aspiration cytology of the stomach. A new diagnostic procedure

In order to improve the diagnosis of submucosal gastric malignancies, a new method of endoscopic fine-needle aspiration cytology was evaluated. The method is compared with conventional forceps biopsy and brush cytology, and technical problems are discussed. It is concluded that endoscopic fine-needle aspiration cytology is a simple and safe procedure, but further development of the method and more clinical experience are required before the diagnostic capability of the method can be established.     

Endoscopic laser therapy in the tracheobronchial system

Their physical properties make lasers ideal instruments for endoscopic surgical procedures in the narrow tracheobronchial system. By the thermal effects of the Nd-YAG laser, pathological benign and, especially, malignant lesions can be destroyed under direct vision. Working without contact with the tissue, sparing the risk of bleeding and further mechanical obstruction the laser has replaced mechanical and electrical devices and cryoprobes in interventional bronchoscopy to a large extent. Thus many patients with benign lesions can be spared the risk of major thoracic surgery of the large airways. To patients suffering from tumours of the central airways the chance of long-term palliation can be given by resolution of life-threatening complications. Eurthermore, by photodynamic laser therapy after application of haematoporphyrin derivatives some patients may even be cured.     

Thalassemia and hemoglobinopathies in Southeast Asian newborns: diagnostic assessment using capillary electrophoresis system

BackgroundWe have investigated the Capillarys 2 Hemoglobin testing system to assist in presumptive diagnosis of thalassemia and hemoglobinopathies commonly found in Southeast Asia.MethodsStudy was conducted on 226 newborns. Hematological parameters were recorded and Hb profiles were examined on the Capillarys 2 Hemoglobin analyzer (SEBIA). DNA analyses were used to establish the final diagnoses.ResultsAmong 226 newborns examined, 122 had thalassemias with 17 different genotypes. The capillary electrophoresis system could provide useful data for presumptive diagnoses of cases, especially those with Hb E and α-thalassemia. Hb E was found to be 2.6–6.2% in heterozygote whereas Hb Bart's were clearly observed in cases with compound heterozygous or homozygous α⁺-thalassemia and heterozygous α⁰-thalassemia. Hb H disease and other forms of α-thalassemia could be differentiated based on the presence of Hb Bart's and its percentage.ConclusionThe capillary electrophoresis system is applicable to newborn screening for common forms of thalassemia in Southeast Asia.     

Detection of urinary bladder cancer cells using redox ratio and double excitation wavelengths autofluorescence

The optical redox ratio as a measure of cellular metabolism is determined by an altered ratio between endogenous fluorophores NADH and flavin adenine dinucleotide (FAD). Although reported for other cancer sites, differences in optical redox ratio between cancerous and normal urothelial cells have not previously been reported. Here, we report a method for the detection of cellular metabolic states using flow cytometry based on autofluorescence, and a statistically significant increase in the redox ratio of bladder cancer cells compared to healthy controls. Urinary bladder cancer and normal healthy urothelial cell lines were cultured and redox overview was assessed using flow cytometry. Further localisation of fluorescence in the same cells was carried out using confocal microscopy. Multiple experiments show correlation between cell type and redox ratio, clearly differentiating between healthy cells and cancer cells. Based on our preliminary results, therefore, we believe that this data contributes to current understanding of bladder tissue fluorescence and can inform the design of endoscopic probes. This approach also has significant potential as a diagnostic tool for discrimination of cancer cells among shed urothelial cells in voided urine, and could lay the groundwork for an automated system for population screening for bladder cancer.OCIS codes: (170.1530) Cell analysis, (110.0110) Imaging systems