Endoscopic video autofluorescence imaging may improve the detection of early neoplasia in patients with Barrett's esophagus

Spectroscopy and fluorescence in esophageal diseases

Malignant tumors of the esophagus continue to be a major health issue associated with high mortality primarily because most present with symptoms of dysphagia or anaemia. The disease at that stage is advanced and not likely curable. The big issue for squamous dysplasia and that associated with BE is that only a small proportion are discovered in surveillance programs when they are asymptomatic, either because the patient lives in a high-incidence geographical area, has a family history, previously diagnosed head and neck cancer or chronic reflux, as in Barrett's. Current endoscopic methods are hampered by the endoscopist's inability to recognize subtle topographic clues of dysplasia, sampling errors related to biopsy protocols, and confounding inflammation-induced artifacts both for the endoscopist and pathologist. What is desperately needed would be a biomarker (e.g. serological, fecal, urinary) that selects patients for endoscopy. However, such a test is not yet on the horizon. This article examines the current status in practice and research of novel optically based 'bioendoscopic' devices (i.e. fluorescence spectroscopy and imaging, confocal fluorescence microendoscopy (CFM), light scattering spectroscopy (LSS), Raman spectroscopy (RS), and immunophotodiagnostic endoscopy) which may enhance the diagnosis of dysplasia in all patients undergoing conventional white light endoscopy. Perhaps these new technologies will lead to more cost-effective diagnosis, mapping (e.g. surface), and staging (e.g. depth) of dysplasia, thereby allowing timely cure by endoscopic means (e.g. EMR and/or PDT), biological interventions (e.g. Cox-2 inhibitors) rather than esophajectomy.

The endoscopic diagnosis and staging of oesophageal adenocarcinoma

The endoscopic evaluation of patients with oesophageal adenocarcinoma does not only serve the purpose of diagnosing the lesion and obtaining biopsies for histological evaluation: a systematic description of advanced lesions is also required to guide further therapeutic decisions. New endoscopic imaging modalities hold the promise of better endoscopic detection of early cancer and its precursor lesions in Barrett's oesophagus. Video-autofluorescence and narrow band imaging are the most promising techniques in this respect. The former may be used as a 'red flag' technique, identifying lesions that remain occult with white light endoscopy; the latter may be used as a targeted imaging technique, allowing for detailed inspection of the mucosal and vascular patterns that may help to distinguish early neoplasia from non-dysplastic tissue. Currently, prototypes are under investigation that combine high-resolution endoscopy, narrow band imaging and video-autofluorescence in one endoscopy system. Endoscopic ultrasonography (EUS) is superior to any other imaging modality in the assessment of local tumour infiltration of oesophageal adenocarcinoma and locoregional lymph nodes status. EUS allows for the identification of patients with advanced disease who are unlikely to benefit from attempts at curative surgery and in whom a conservative palliative treatment is indicated. EUS may also play a role in the selection of patients for local endoscopic treatment of early oesophageal cancer. EUS guided fine needle aspiration (EUS-FNA) of locoregional lymph nodes is safe with a high sensitivity and an impeccable specificity for assessment of malignant involvement. The indications for EUS-FNA of lymph nodes, however, depend on local treatment protocols: caeliac nodes (M1a) and lymph nodes located at or above the subcarinal area are the most widely used indications. In addition, it may be important if the choice for specific treatment protocols (e.g. neoadjuvant chemoradiotherapy) depends on lymph node status.

Endoscopic detection of early upper GI cancers

The detection of early-stage neoplastic lesions in the upper GI tract is associated with improved survival and the potential for complete endoscopic resection that is minimally invasive and less morbid than surgery. Despite technological advances in standard white-light endoscopy, the ability of the endoscopist to reliably detect dysplastic and early cancerous changes in the upper GI tract remains limited. In conditions such as Barrett's oesophagus, practice guidelines recommend periodic endoscopic surveillance with multiple biopsies, a methodology that is hindered by random sampling error, inconsistent histopathological interpretation, and delay in diagnosis. Early detection may be enhanced by several promising diagnostic modalities such as chromoendoscopy, magnification endoscopy, and optical spectroscopic/imaging techniques, as these modalities offer the potential to identify in real-time lesions that are inconspicuous under conventional endoscopy. The combination of novel diagnostic techniques and local endoscopic therapies will provide the endoscopist with much needed tools that can considerably enhance the detection and management of early stage lesions in the upper GI tract.

Interventional endoscopy

PURPOSE OF REVIEW

This review is an update of key issues in gastric interventional endoscopy. It focuses on the areas of patient preparation, endoscopic mucosal resection, gastroduodenal stenting, and endoscopic placement of enteric feeding tubes.

RECENT FINDINGS

Clopidogel (Plavix), a newer antiplatelet agent, can increase the risk of bleeding. Therefore, in selected cases, it should be held for 7-10 days prior to interventional procedures. In experienced hands, endoscopic mucosal resection (success rate, 76-100%; complication rate, 4-28%) and gastroduodenal stenting (success rate, 81-92%; complication rate, 1-17%) seem to be safe and effective techniques.

SUMMARY

The field of interventional endoscopy continues to advance and to conquer new frontiers. These advances create new problems that need to be addressed and studied by researchers, however. It is only through these types of reviews that our state of knowledge can be updated to help provide the latest information for clinicians in the field and to challenge researchers with future problems that need to be studied.

New imaging techniques at colonoscopy: tissue spectroscopy and narrow band imaging

Although colonoscopy has undergone impressive development in recent decades, there remains a need for better endoscopic visualization in specific circumstances (eg, dysplasia screening in ulcerative colitis and detection of flat colorectal lesions). Many techniques are under investigation; this article discusses different forms of spectroscopy and narrow band imaging. Ideal colonoscopy should have high diagnostic accuracy and the ability to screen large mucosal areas. The most successful clinical method probably will be a combination of techniques, providing wide-area surveillance (such as fluorescence endoscopy or immunoscopy) and point detection methods, such as narrow band imaging or confocal microendoscopy, that can be used to identify the lesion further.

Optical spectroscopy for the detection of dysplasia in Barrett's esophagus

Patients with Barrett's esophagus (BE) undergo periodic endoscopic surveillance with multiple biopsy examinations in an attempt to identify dysplastic and early cancerous lesions at a time when intervention can be beneficial. However, this surveillance approach is hindered by low sampling yield, random sampling error, pathology-associated costs, and delay in diagnosis. Optical spectroscopy offers the potential to identify tissue pathology accurately in real time. The technique uses diagnostic molecular and/or microstructural information contained in light-tissue interactions such as fluorescence, elastic scattering, and inelastic (Raman) scattering. As an adjunct to endoscopy, optical spectroscopy has the capacity to enhance lesion detection in premalignant conditions such as BE. This article highlights the current status and future prospects of optical spectroscopy in BE.

A randomized crossover study comparing light-induced fluorescence endoscopy with standard videoendoscopy for the detection of early neoplasia in Barrett's esophagus

BACKGROUND

Light-induced fluorescence endoscopy (LIFE) may improve the detection of high-grade dysplasia (HGD) and early stage cancer (EC) in Barrett's esophagus (BE). The aim of this study was to compare LIFE with standard endoscopy (SE) in a randomized crossover study.

METHODS

Fifty patients with BE underwent SE and LIFE in a randomized sequence (4 to 6-week interval between procedures). The two procedures were performed by two different endoscopists who were blinded to the findings of the other examination. Targeted biopsy specimens were taken from detected lesions, followed by random biopsy specimens with a 2-cm interval, 4-quadrant protocol. Biopsy specimens were routinely evaluated and subsequently reviewed by a single, blinded expert GI pathologist.

RESULTS

Targeted biopsy specimens had a sensitivity for the diagnosis of HGD/EC of 62% (8/13) for both techniques. The overall sensitivity (all biopsy specimens) was 85% for SE and 69% for LIFE (p = 0.69). All targeted biopsy specimens had a positive predictive value (PPV) for HGD/EC of 41% for SE and 28% for LIFE (p = 0.40); autofluorescence-targeted biopsy specimens had a PPV of 13%. False-positive lesions had a significantly higher rate of acute inflammation than random biopsy specimens.

CONCLUSIONS

In this study, LIFE did not improve the detection of HGD or EC in patients with BE compared with SE.