Advances in Endoscopic Imaging

SGNA meetingFebruary 20, 2010

Amar R. Deshpande, MD

Asst Professor of Medicine

Division of Gastroenterology

University of Miami Miller School of Medicine

Objectives

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

Why do endoscopy?Many indications for upper and lower endoscopyWe will focus on identification (and therefore removal) of precancerous lesions

adenomatous colon polypsBarrett esophagus with dysplasiaflat dysplasia in inflammatory bowel disease

Finding lesions in earlier stages leads to better survival and cure rates

Conventional EndoscopyAlso referred to as white-light endoscopy (WLE)◦ current gold standard for detection and removal

of pre-cancerous lesionsHowever, 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 visualizeTherefore, new modalities are needed◦ improved crypt and capillary pattern visualization

can help classify mucosal lesions/polypsvan Rijn JC, Reitsma JB, et al. Polyp miss rate determined by tandem colonoscopy: a systematic review. American

Journal of Gastroenterology 2006 Feb;101(2):343-50.Suzuki N, Saunders BP, Brown G. Flat colorectal neoplasms: endoscopic detection, clinical relevance and

management. Techniques in Coloproctology 2004 Dec;8 Suppl2:s261-6.

Armamentarium of Endoscopy

Digital advances in white-light endoscopy◦ High definition (HD) endoscopy

uses high-density pixel CCD chips (resolution ∞ pixel density)

◦ Magnification endoscopycan magnify 1.5x to 150xoptical zoom maintains resolution, electronic zoom does not

Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr OpinGastroenterol 2009 Sep;25(5):412-21.

Bruno NJ. Magnification endoscopy, high resolution endoscopy: towards a better optical diagnosis. Gut 2003; 52(suppl.4):7-11.

Armamentarium of Endoscopy

Using dyes to highlight mucosal surface abnormalities (chromoendoscopy)◦ 1st 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 (1887-1960). Obstet Gynecol Surv. 2004 May;59(5):319-20.

Tada M, Katoh S, Kohli Y, et al. On the dye spraying method in colonofiberoscopy. Endoscopy 1977 May;8(2):70-4.

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].

hyperplastic adenoma(papillary) (nonbranched)

Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr OpinGastroenterol 2009 Sep;25(5):412-21.

Armamentarium of Endoscopy

Digital filtering techniques (virtual chromoendoscopy)

◦ Narrow-band imaging (NBI)

◦ Post-image acquistion techniquesFujinon intelligent chromoendoscopy (FICE)i-scan (Pentax)

NBI

All colors have different wavelengthsWhat 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 colorsBy narrowing the band-width (415-540nm – blues and greens, not reds), capillary definition can be noted

www.olympus-global.com/.../nr061226evisse.cfm

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

Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr OpinGastroenterol 2009 Sep;25(5):412-21.

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 mucosagreen is normal mucosapurple is areas of attenuated fluorescence abnormal mucosa

WLE (a), AFI (b), NBI (c)

Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr OpinGastroenterol 2009 Sep;25(5):412-21.

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

Goetz M, Kiesslich R. Advanced imaging of the gastrointestinal tract: research vs. clinical tools? Curr OpinGastroenterol 2009 Sep;25(5):412-21.

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

DrawbacksMore time-consumingMost 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

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 time-consuming and have not yet clearly shown to positively impact survivalStill a work in progress…