Spectral variations in narrow band imaging depth-selectivity: Mucosal scattering vs. hemoglobin absorption

Quanzeng Wang, Du Le, Jessica C. Ramella-Roman, Joshua Pfefer

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Spectral variations in contrast enhancement of mucosal vasculature are a key feature of narrow band imaging (NBI) devices. In prior NBI studies, the enhanced visualization of larger, deeper vessels with green light (e.g., 540 nm) relative to violet light (e.g., 415 nm) has often been attributed to the well-known monotonic decrease in scattering coefficient with wavelength in biological tissues. We have developed and implemented numerical and experimental approaches to elucidate and quantify this and other light-tissue interaction effects relevant to NBI. A Monte Carlo model incorporating vessel-like inclusions with a range of diameters (20 to 400 microns) and depths (20 to 400 microns) was used to predict reflectance and fluence distributions in the tissue and calculate vessel contrast values. These results were compared to experimental measurements based on a liquid phantom with a hemoglobin-filled capillary. By comparing results for cases representing mucosa regions with and without blood, we were able to evaluate the relative significance of absorption and scattering on spectral variations in depth-selectivity. Results indicate that at 415 nm, detection of superficial vasculature with NBI was almost entirely dependent on the absorption coefficient of the blood in the vessel of interest. The enhanced visualization of deep vessels at 540 nm bands relative to 415 nm was due primarily to absorption by the superficial vasculature rather than a decrease in scattering coefficient. While computationally intensive, our numerical modeling approach provides unique insights into the light propagation mechanisms underlying this emerging clinical imaging technology.

Original languageEnglish (US)
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
StatePublished - 2013
Externally publishedYes
EventDesign and Quality for Biomedical Technologies VI - San Francisco, CA, United States
Duration: Feb 2 2013Feb 3 2013


OtherDesign and Quality for Biomedical Technologies VI
Country/TerritoryUnited States
CitySan Francisco, CA

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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