Advances in Endoscopic Imaging

Transcription

1 Advances in Endoscopic Imaging SGNA meeting February 20, 2010 Amar R. Deshpande, MD Asst Professor of Medicine Division of Gastroenterology University of Miami Miller School of Medicine

2 Objectives To recognize new technologies available to detect abnormal mucosal findings To gain an understanding of the principles of the various types of endoscopic imaging To appreciate the role of advanced imaging in endoscopic practice

3 Why do endoscopy? Many indications for upper and lower endoscopy We will focus on identification (and therefore removal) of precancerous lesions adenomatous colon polyps Barrett esophagus with dysplasia flat dysplasia in inflammatory bowel disease Finding lesions in earlier stages leads to better survival and cure rates

4 Conventional Endoscopy Also referred to as white-light endoscopy (WLE) current gold standard for detection and removal of pre-cancerous lesions However, there is a clear miss rate up to 22% of polyps seen on tandem colonoscopy were missed on first study non-raised lesions can be the hardest to visualize Therefore, new modalities are needed improved crypt and capillary pattern visualization can help classify mucosal lesions/polyps van Rijn JC, Reitsma JB, et al. Polyp miss rate determined by tandem colonoscopy: a systematic review. American Journal of Gastroenterology 2006 Feb;101(2): Suzuki N, Saunders BP, Brown G. Flat colorectal neoplasms: endoscopic detection, clinical relevance and management. Techniques in Coloproctology 2004 Dec;8 Suppl2:s261-6.

5 Armamentarium of Endoscopy Digital advances in white-light endoscopy High definition (HD) endoscopy uses high-density pixel CCD chips (resolution pixel density) Magnification endoscopy can magnify 1.5x to 150x optical zoom maintains resolution, electronic zoom does not

6 Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr Opin Gastroenterol 2009 Sep;25(5): Bruno NJ. Magnification endoscopy, high resolution endoscopy: towards a better optical diagnosis. Gut 2003; 52(suppl.4):7-11.

7 Armamentarium of Endoscopy Using dyes to highlight mucosal surface abnormalities (chromoendoscopy) 1 st described in the 1920s in cervical dysplasia with Lugol s solution, squamous epithelium (highly glycogenated) was dark, dysplasia/neoplasia was not described in the 1970s at colonoscopy; fine mucosal changes and inflammation seen with dye (indigo carmine and methylene blue) in patients with UC Powell JL. Biographic sketch: Powell's Pearls: Walter Schiller, MD ( ). Obstet Gynecol Surv May;59(5): Tada M, Katoh S, Kohli Y, et al. On the dye spraying method in colonofiberoscopy. Endoscopy 1977 May;8(2):70-4.

8 Armamentarium of Endoscopy Different dye options absorptive (methylene blue, Lugol s iodine, toluidine blue): taken up by the mucosa of specialized epithelium (e.g. Barrett) reactive (Congo red, acetic acid): change color on contact with specific cellular constituents expressed in diseased mucosa contrast (Indigo carmine): pool in crevices and depressions within the mucosa, accentuating uneven mucosal surfaces Yeung TM, Mortensen NJ. Advances in endoscopic visualization of colorectal polyps. Colorectal Dis 2009 Nov 23. [Epub ahead of print].

9 hyperplastic (papillary) adenoma (nonbranched) Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr Opin Gastroenterol 2009 Sep;25(5):

10 Armamentarium of Endoscopy Digital filtering techniques (virtual chromoendoscopy) Narrow-band imaging (NBI) Post-image acquistion techniques Fujinon intelligent chromoendoscopy (FICE) i-scan (Pentax)

11 NBI All colors have different wavelengths What we see is what is reflected (everything else is absorbed) In traditional white-light endoscopy, it is hard to see capillary patterns (red) due to scattering from other colors By narrowing the band-width ( nm blues and greens, not reds), capillary definition can be noted

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13 FICE and i-scan use post-image acquisition algorithms to modulate the light reflected from the mucosa, highlighting surface contrast, vessel pattern and pit pattern

14 Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr Opin Gastroenterol 2009 Sep;25(5):

15 Armamentarium of Endoscopy Autofluorescence imaging (AFI) submucosa produces green fluorescence when exited by blue light abnormalities in mucosa or its capillaries above the submucosa blunt the intensity differences in fluorescence can suggest abnormal mucosa green is normal mucosa purple is areas of attenuated fluorescence abnormal mucosa

16 WLE (a), AFI (b), NBI (c) Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr Opin Gastroenterol 2009 Sep;25(5):

17 Armamentarium of Endoscopy Confocal microscopy + endoscopy Confocal Laser Endomicroscopy (CLE) need to inject dye intravenously as well Endoscopically localize an abnormal area (e.g. tongue of Barrett, polyp), then apply confocal microscopy to evaluate on a cellular level Because of need for localization, may need to combine with chromoendoscopy for general dysplasia screening (e.g. UC)

18 Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr Opin Gastroenterol 2009 Sep;25(5):

19 Does it make a difference? Many trials have looked at each of these modalities vs WLE dysplasia screening in Barrett esophagus dysplasia screening in IBD detection of subtle adenomatous lesions Most have shown improved detection of dysplastic or adenomatous changes and the ability to target biopsies

20 Drawbacks More time-consuming Most endoscopists would need training: interpreting pit patterns and capillary formations interpreting microscopic findings No convincing data to support improved survival in those whose <6mm adenomas are removed perhaps CT colography (in which patients with small polyps are followed radiographically) will provide more insight

21 Conclusions There are many new endoscopic imaging modalities that have allowed: visualization of subtle or flat lesions improved detection of dysplasia targeting of biopsies These modalities are more timeconsuming and have not yet clearly shown to positively impact survival Still a work in progress