Kurdistan Board GEH/GIT Surgery weekly J Club:Supervised by:

Professor Dr.Mohamed AlshekhaniMBChB-CABM,FRCP,EBGH.Frontline Gastroenterology

2016;7:207–215.

Introduction:Introduction: Identifying early pathology & precursor lesions, Identifying early pathology & precursor lesions,

needs an improvement in technology.needs an improvement in technology. New imaging systems, not all widely available, New imaging systems, not all widely available,

&costy. &costy. As yet there is no single imaging modality As yet there is no single imaging modality

applicable all clinical scenarios, therefore an applicable all clinical scenarios, therefore an understanding of all of these techniques is understanding of all of these techniques is required.required.

Types: HD WLETypes: HD WLE High Definition (HD) endoscopes use light from a High Definition (HD) endoscopes use light from a

xenon lamp, with the light detected by HD charge xenon lamp, with the light detected by HD charge coupled device located at the tip of the scope. coupled device located at the tip of the scope.

Images can be enhanced further when combined Images can be enhanced further when combined with optical zoom lenses, capable of magnifying with optical zoom lenses, capable of magnifying images by up to 150 times.images by up to 150 times.

Types: NBITypes: NBI These wavelengths coincide with the optimal These wavelengths coincide with the optimal

frequency absorbed by frequency absorbed by haemoglobin, haemoglobin, accentuating surface microvasculature&accentuating surface microvasculature&providing providing enhanced delineation of the mucosal enhanced delineation of the mucosal architecture. architecture.

As angiogenesis is one of the first features of As angiogenesis is one of the first features of neoplasia, lesionsneoplasia, lesions

appear darker than the background mucosa.appear darker than the background mucosa.

Types: Blue laser lightTypes: Blue laser light Blue laser light (Lasero, Fujinon) combines two Blue laser light (Lasero, Fujinon) combines two

lasers, one highlights mucosal abnormalities lasers, one highlights mucosal abnormalities &second laser provides fluorescent white light, &second laser provides fluorescent white light, enabling improved illumination of the mucosal enabling improved illumination of the mucosal surface, allowing for brighter images than surface, allowing for brighter images than achieved with traditional NBI. achieved with traditional NBI.

Types: FICETypes: FICE A virtual chromoendoscopic technique, using A virtual chromoendoscopic technique, using

postprocessing algorithms, is able to digitally postprocessing algorithms, is able to digitally convert HD WLE images into colour images convert HD WLE images into colour images composed of various wavelength combinationscomposed of various wavelength combinations

The ten available presets can be customised from The ten available presets can be customised from the many possible permutations, with an the many possible permutations, with an appropriate setting chosen on the basis of lesion appropriate setting chosen on the basis of lesion characteristics.characteristics.

Types: I ScanTypes: I Scan I-Scan (Pentax Medical,) similarly detects white I-Scan (Pentax Medical,) similarly detects white

light reflected by GI mucosa, converting this light reflected by GI mucosa, converting this using postprocessing software to enhance lesion using postprocessing software to enhance lesion characteristics. characteristics.

I-Scan has three different I-Scan has three different modes; surface modes; surface enhancement, contrast enhancement&enhancement, contrast enhancement&tone tone enhancement modes. enhancement modes.

By augmenting light contrast, suppressing visible By augmenting light contrast, suppressing visible red light & enhancing blue light, it is possible in red light & enhancing blue light, it is possible in the various modes to provide topographical the various modes to provide topographical information & enhance information & enhance mucosal vasculature.mucosal vasculature.

Types: AFITypes: AFI Autofluorescence imaging (AFI) takes advantage Autofluorescence imaging (AFI) takes advantage

of the differential presence of naturally occurring of the differential presence of naturally occurring endogenous fluorophores within the GI mucosa. endogenous fluorophores within the GI mucosa.

This results in an image composed of a mixture This results in an image composed of a mixture of green/mauve hues, which represent areas of of green/mauve hues, which represent areas of normal/dysplastic mucosa, respectivelynormal/dysplastic mucosa, respectively

Types: CLETypes: CLE Confocal laser endomicroscopy works by focusing Confocal laser endomicroscopy works by focusing

blue laser light through a single lens onto a blue laser light through a single lens onto a specific target. specific target.

The reflected light is filtered through a pinhole, The reflected light is filtered through a pinhole, thereby reducing light scatter, creating highly thereby reducing light scatter, creating highly detailed images from a thin focal plane.detailed images from a thin focal plane.

This is available as a miniature scanner This is available as a miniature scanner integrated onto the endoscope tip or separately integrated onto the endoscope tip or separately as a probe-based accessory fed through the as a probe-based accessory fed through the working channel of a standard endoscope.working channel of a standard endoscope.

Administration of an intravenous fluorescent Administration of an intravenous fluorescent contrast agent is necessary in order to achieve contrast agent is necessary in order to achieve delineation of the subsurface architecture.delineation of the subsurface architecture.

CLE offers image detail comparable to CLE offers image detail comparable to histopathological sections.histopathological sections.

Eso applications:Eso applications: Barrett’ s oesophagus annual risk of progression of Barrett’ s oesophagus annual risk of progression of

0.33%.0.33%. The standard of care is currently the Seattle The standard of care is currently the Seattle

protocol, with quadrantic biopsies taken at 2 cm protocol, with quadrantic biopsies taken at 2 cm intervals within the Barrett’ s segment. intervals within the Barrett’ s segment.

A meta-analysis demonstrated sensitivity/specificity A meta-analysis demonstrated sensitivity/specificity of 96% /and 94%, respectively, for the detection of of 96% /and 94%, respectively, for the detection of high-grade dysplasia.high-grade dysplasia.

AFI has shown initial promising results in increasing AFI has shown initial promising results in increasing dysplasia detection but unfortunately is associated dysplasia detection but unfortunately is associated with a high false positive rate, which can be as high with a high false positive rate, which can be as high as 80% so incorporated with NBI & HD WLE to as 80% so incorporated with NBI & HD WLE to create endoscopic trimodal imaging (ETMI). create endoscopic trimodal imaging (ETMI).

The use of AFI is currently limited to expert The use of AFI is currently limited to expert endoscopists in high-risk endoscopists in high-risk patients.patients.

Eso applications:Eso applications: A meta-analysis found the sensitivity of CLE in A meta-analysis found the sensitivity of CLE in

the detection of neoplasia to be 89%, with fewer the detection of neoplasia to be 89%, with fewer biopsies required compared with WLE biopsies required compared with WLE assessment.assessment.

At present there is insufficient evidence for the At present there is insufficient evidence for the use of optical imaging techniques in preference use of optical imaging techniques in preference of quadrantic biopsies for routine Barrett’ s of quadrantic biopsies for routine Barrett’ s surveillance.surveillance.

These have proven useful in high-risk patients, in These have proven useful in high-risk patients, in whom quadrantic biopsies have detected the whom quadrantic biopsies have detected the presence of dysplasia and in the context of presence of dysplasia and in the context of treatment planning, where accurate delineation treatment planning, where accurate delineation of lesion margins prior to resection is paramount.of lesion margins prior to resection is paramount.

Stomach applications:Stomach applications: At present, where atrophy is suspected it is At present, where atrophy is suspected it is

recommended that biopsies are taken as per the recommended that biopsies are taken as per the Sydney protocol, with non-targeted biopsies within the Sydney protocol, with non-targeted biopsies within the antrum, incisura & fundus.antrum, incisura & fundus.

HD WLE allows for the detection of IM&dysplasia with HD WLE allows for the detection of IM&dysplasia with a sensitivity of 76% & 97%, respectively,while the use a sensitivity of 76% & 97%, respectively,while the use of magnification NBI has been shown to be accurate in of magnification NBI has been shown to be accurate in differentiating between malignant&normal mucosa differentiating between malignant&normal mucosa with a sensitivity of 97%. In high risk patients as in with a sensitivity of 97%. In high risk patients as in JapanJapan

FICE When used for assessment prior to endoscopic FICE When used for assessment prior to endoscopic mucosal dissection helps to achieve clear resection mucosal dissection helps to achieve clear resection margins.margins.

Evidence for the use of I-Scan is still preliminary.Evidence for the use of I-Scan is still preliminary. CLE have demonstrated very promising results, When CLE have demonstrated very promising results, When

combined with NBI there is 82% accuracy in combined with NBI there is 82% accuracy in histological classification of early gastric neoplasia.histological classification of early gastric neoplasia.

Colon applications:Colon applications: Screening associated with 80% reduction in the Screening associated with 80% reduction in the

subsequent development CRCsubsequent development CRC..

Colon applications:ADRColon applications:ADR Despite its benefits colonoscopy is limited by Despite its benefits colonoscopy is limited by

polyp miss rates of up to 26%.polyp miss rates of up to 26%. Disappointingly, studies evaluating the use of HD Disappointingly, studies evaluating the use of HD

WLE have shown only a modest improvement in WLE have shown only a modest improvement in ADR. ADR.

There is no convincing evidence for increased There is no convincing evidence for increased ADRs associated with the use of AFI, CLE, I-Scan ADRs associated with the use of AFI, CLE, I-Scan or FICE.or FICE.

Colon applications:Polyp Colon applications:Polyp typetype

Use of NBI for optical diagnosis proven accurate Use of NBI for optical diagnosis proven accurate when performed by experts.when performed by experts.

There was 91% accuracy for diagnosing There was 91% accuracy for diagnosing neoplastic polyps, which when coupled with high neoplastic polyps, which when coupled with high confidence predictions resulted in an increased confidence predictions resulted in an increased diagnostic accuracy.diagnostic accuracy.

The use of FICE and I-Scan are comparable to the The use of FICE and I-Scan are comparable to the use of NBI.use of NBI.

CLE has proven to be highly sensitive CLE has proven to be highly sensitive (95%)&specific (94%) among 11 pooled trials (95%)&specific (94%) among 11 pooled trials &the most promising.&the most promising.

Colon applications:IBD Colon applications:IBD dysplasiadysplasia

Dye-based chromoendoscopy with methylene blue can Dye-based chromoendoscopy with methylene blue can increase dysplasia detection rates threefold to increase dysplasia detection rates threefold to fourfold.fourfold.

To date NBI has been shown to be comparable to HD To date NBI has been shown to be comparable to HD WLE combined with chromoendoscopy, rather than WLE combined with chromoendoscopy, rather than superior. superior.

It is not yet clear whether AFI has a role in dysplasia It is not yet clear whether AFI has a role in dysplasia detection in UC. detection in UC.

review of images taken withreview of images taken with WLE & AFI showed a good correlation.WLE & AFI showed a good correlation. To date CLE has demonstrated an impressive 97% To date CLE has demonstrated an impressive 97%

accuracy in differentiating between dysplasia-accuracy in differentiating between dysplasia-associated lesions or masses& adenoma-like masses associated lesions or masses& adenoma-like masses &more sensitive in detecting dysplasia than WLE with &more sensitive in detecting dysplasia than WLE with dyebased chromoendoscopy,but time-consuming dyebased chromoendoscopy,but time-consuming nature so unlikely to be pragmatic for standard nature so unlikely to be pragmatic for standard surveillance.surveillance.

Emerging newer technos:Emerging newer technos: Optical coherence tomography:Optical coherence tomography:

Emerging newer technos:Emerging newer technos: SpectroscopySpectroscopy These are , narrow field techniques, allowing for These are , narrow field techniques, allowing for

interrogation of a single point at a time and are interrogation of a single point at a time and are therefore time-consuming.therefore time-consuming.

Emerging newer technos:Emerging newer technos: Molecular imagingMolecular imaging Identifying abnormal tissue by means of the Identifying abnormal tissue by means of the

differential expression molecules in health & differential expression molecules in health & disease. disease.

The use of glycans as a molecular target has been The use of glycans as a molecular target has been described in Barrett’s oesophagus, with described in Barrett’s oesophagus, with fluorescently labelled lectins used to highlight fluorescently labelled lectins used to highlight dysplastic tissue with high specificity.dysplastic tissue with high specificity.

Abstract:Abstract: Aim to detect early lesions amenable to curative endoscopic Aim to detect early lesions amenable to curative endoscopic

trt.trt. This requires an improvement in diagnostics, with a focus on This requires an improvement in diagnostics, with a focus on

identifying & characterising subtle mucosal changes. identifying & characterising subtle mucosal changes. Optical technologies used to predict histology& enable the Optical technologies used to predict histology& enable the

formulation of a real-time in vivo diagnosis ‘optical biopsy’. formulation of a real-time in vivo diagnosis ‘optical biopsy’. In selected situations advanced imaging techniques are In selected situations advanced imaging techniques are

useful for optical diagnosis of GI pathology. useful for optical diagnosis of GI pathology. To date most used in clinical trials or within tertiary To date most used in clinical trials or within tertiary

hospitals with selected populations.hospitals with selected populations. These techniques however, represent progress in terms of These techniques however, represent progress in terms of

diagnostic capability &paradigm shift in the role of diagnostic capability &paradigm shift in the role of endoscopy in patient management. endoscopy in patient management.

Optical imaging is undoubtedly a useful addition in the Optical imaging is undoubtedly a useful addition in the armamentarium for the diagnosis of treatable early GIT armamentarium for the diagnosis of treatable early GIT pathology.pathology.