Three-dimensional endomicroscopy of the human colon using optical coherence tomography

Abstract

Three-dimensional (3D) endomicroscopy imaging of the human gastrointestinal tract is demonstrated in vivo using a swept source optical coherence tomography (OCT) system. 3D datasets of normal and pathologic regions of the colon, rectum, and anal verge were obtained from seven volunteers undergoing diagnostic or therapeutic colonoscopy. 3D-OCT enables high resolution endomicroscopy examination through visualization of tissue architectural morphology using virtual cross-sectional images with arbitrary orientations as well as en face projection images. Axial image resolutions of 6 mum in tissue are obtained over a approximately 180 mm2 field with an imaging range of 1.6 mm. A Fourier domain mode locked (FDML) laser providing a tuning range of 180 nm at a sweep rate of 62 kHz is used as the system light source. This clinical pilot study demonstrates the potential of 3D-OCT for distinguishing normal from pathologic colorectal tissue, assessing endoscopic therapies and healing progression.

Fig. 1

3D-OCT images of columnar epithelial tissue in the human colon. a, En face image constructed by axial summation of the entire dataset. Dashed lines show locations of cross-sections. b, XZ cross-section showing typical columnar structure. c, YZ cross-section. d, Enlarged view of a, showing en face crypt pattern. e, Representative en face histology of human colon. f, White light video endoscopy image of region analyzed with 3D-OCT.

Fig. 2

3D-OCT images near the dentate line. a, En face image constructed by axial summation of entire dataset. Dashed lines show locations of cross-sections. b, XZ cross-section showing typical squamous structure. c, YZ cross-section showing shift from columnar C to squamous S epithelium over a transition zone T. d, White light video endoscopy image of region analyzed with 3D-OCT. e, Representative cross-sectional histology of columnar epithelium. f, Representative cross-sectional histology of squamous epithelium. Arrows in b and f indicate normal anal vessels.

Fig. 3

Conventional examination of UC. a, White light video endoscopy image of UC showing the 3D-OCT probe in position. The tissue surface is inflamed with ulcerations and bleeding. b, Representative cross-sectional histology of UC showing an ulcerative pseudo-polyp.

Fig. 4

3D-OCT images of ulcerative colitis. a, En face image constructed by summation of 20 um axial section. Large subsurface voids and ulcerations are present, while regular crypt pattern is absent. Dashed lines show locations of cross-sectional images. b, XZ cross-section containing normal squamous epithelium S and ulcerative colitis U. c, YZ cross-section showing similar structure. d, Enlarged view of left portion of c, showing disorganized structure and superficial voids. e, Enlarged view of right portion of c, showing regular squamous epithelium. (Media 1)

Fig. 5

Conventional examination of radiation proctitis. a, White light video endoscopy image of radiation proctitis prior to treatment with radiofrequency ablation. Arrows indicate regions of bleeding and ulceration. b, Image 12 months after treatment. c, Image 14 months after treatment. d, Representative cross-sectional histology image of radiation proctitis. Arrow indicates a large superficial vessel.

Fig. 6

3D-OCT images of radiation proctitis 12 months after treatment. a, Full thickness en face summation. Arrow indicates a large abnormality. b, 20 um en face summation. Subsurface vessels and voids are present. Dashed lines show locations of cross-sectional images. c, XZ cross-section showing irregular epithelium with vascular structures V. Dashed line shows depth of the en face image in b. d-f, YZ cross-sections showing similar features, including vascular structures V and superficial focal fibrosis F. (Media 2)

Fig. 7

3D-OCT images of radiation proctitis 14 months after treatment. a, 20 um en face summation. Columnar epithelium proximal of the dentate line appears normal. Squamous epithelium is largely normal, with likely former ectatic vessels shown by arrows. Dashed lines show locations of cross-sectional images. b, XZ cross-section showing regular squamous S and columnar C epithelium. c, YZ cross-sections showing similar features. d, Arbitrary cross-section through the long axis of an ectatic vessel remnant R. (Media 3)