title: High-resolution endoscopic imaging of the GI tract using optical coherence tomography.
abstract: BACKGROUND
  Optical coherence tomography (OCT) has demonstrated the microscopic structure of the gastrointestinal (GI) tract mucosa and submucosa in vitro. We evaluated a prototype OCT system and assessed the feasibility of OCT in the human GI tract.
  
  
  METHODS
  The 2.4 mm diameter prototype OCT probe, inserted through an endoscope, provides a 360-degree radial scan. Images (6.7 frames/sec) are displayed on a television monitor. Tissue contact is not required. In patients undergoing elective endoscopy, OCT images were obtained of normal mucosa (confirmed by biopsy).
  
  
  RESULTS
  Seventy-two sites were imaged (38 patients): esophagus (21), stomach (12), duodenum (11), terminal ileum (4), colon (15), and rectum (9). Varying the distance between the probe and the mucosal surface produced images of the GI wall of varying depth. When held about 1 mm above the mucosal surface, the images consisted of mucosal structures such as colonic crypts, gastric pits, and duodenal villi. With the probe held against the wall, the OCT image comprised several layers interpreted as mucosa, muscularis mucosae, and submucosa. Structures including blood vessels were evident within the submucosa. A probe with a 0.5 mm working distance to the focal point provided the best images. Reducing the frame rate to 4.0 per second facilitated image interpretation.
  
  
  CONCLUSIONS
  OCT is feasible in the human GI tract and provides interpretable high-resolution images of mucosa and submucosa.
authors.affiliation: Department of Medicine, Division of Gastroenterology, School of Biomedical Engineering, and Department of Pathology, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Ohio 44106, USA.
authors.forename: M V
authors.initials: MV
authors.lastname: Sivak
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: J A
authors.initials: JA
authors.lastname: Izatt
authors.forename: A M
authors.initials: AM
authors.lastname: Rollins
authors.forename: R
authors.initials: R
authors.lastname: Ung-Runyawee
authors.forename: A
authors.initials: A
authors.lastname: Chak
authors.forename: R C
authors.initials: RC
authors.lastname: Wong
authors.forename: G A
authors.initials: GA
authors.lastname: Isenberg
authors.forename: J
authors.initials: J
authors.lastname: Willis
mesh_terms: D000328:Adult; D000368:Aged; D019412:Anatomy, Cross-Sectional; D004064:Digestive System / Q000033:anatomy & histology*; D005260:Female; D005753:Gastric Mucosa / Q000033:anatomy & histology*; D005767:Gastrointestinal Diseases / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007413:Intestinal Mucosa / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D012680:Sensitivity and Specificity; D014054:Tomography / Q000295:instrumentation / Q000379:methods*