title: Elastic scattering spectroscopy as an optical marker of inflammatory bowel disease activity and subtypes.
abstract: BACKGROUND
  In 10% to 15% of individuals, inflammatory bowel disease (IBD) is difficult to classify as ulcerative colitis (UC) or Crohn's disease (CD). Previous work has demonstrated that probe-based elastic scattering spectroscopy (ESS) can produce spectra, informed by parameters like tissue ultrastructure and hemoglobin content, capable of differentiating pathologies. This study investigates whether ESS is an in vivo optical biomarker for the presence, activity, and type of IBD in the colon.
  
  
  METHODS
  Pilot study, a retrospective data analysis. ESS spectra of endoscopically normal and inflamed colon were obtained from 48 patients with IBD and 46 non-IBD controls. Measurements from patients with IBD were categorized as CD or UC based on clinical diagnosis. Spectra were analyzed using high-dimensional methods. Leave-one-patient-out cross-validation was used to obtain diagnostic performance estimates.
  
  
  RESULTS
  Patients with IBD were distinguishable from non-IBD controls with a sensitivity of 0.93 and specificity of 0.91 based on readings from endoscopically normal mucosa, and 0.94 and 0.93 from inflamed mucosa. In patients with IBD, histologically normal and inflamed colon were distinguishable with per-class accuracies of 0.83 and 0.89, respectively; histologically normal from inactive inflammation with accuracies of 0.73 and 0.89, respectively; and inactive from active colitis with accuracies of 0.87 and 0.84, respectively. The diagnosis of CD versus UC was made with per-class accuracies of 0.92 and 0.87 in normal and 0.87 and 0.85 in inflamed mucosa, respectively.
  
  
  CONCLUSIONS
  ESS, a simple, low-cost clinically friendly optical biopsy modality, has the potential to enhance the endoscopic assessment of IBD and its activity in real time and may help to distinguish CD from UC.
authors.affiliation: *Department of Medicine, Section of Gastroenterology, Boston University School of Medicine, Boston, Massachusetts; †Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; ‡Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts; §Department of Biomedical Engineering, College of Engineering, Boston University, Boston, Massachusetts; and ‖Gastroenterology Unit, Medical Service, VA Boston Healthcare System, Boston, Massachusetts.
authors.forename: Eladio
authors.initials: E
authors.lastname: Rodriguez-Diaz
authors.forename: Christopher
authors.initials: C
authors.lastname: Atkinson
authors.forename: Lisa I
authors.initials: LI
authors.lastname: Jepeal
authors.forename: Adam
authors.initials: A
authors.lastname: Berg
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Huang
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Cerda
authors.forename: Michael J
authors.initials: MJ
authors.lastname: OʼBrien
authors.forename: Irving J
authors.initials: IJ
authors.lastname: Bigio
authors.forename: Francis A
authors.initials: FA
authors.lastname: Farraye
authors.forename: Satish K
authors.initials: SK
authors.lastname: Singh
mesh_terms: D000328:Adult; D000368:Aged; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000473:pathology; D003106:Colon / Q000473:pathology; D003424:Crohn Disease / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology; D008297:Male; D008875:Middle Aged; D061848:Optical Imaging / Q000379:methods* / Q000592:standards; D010865:Pilot Projects; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013057:Spectrum Analysis