title: Visible reflectance hyperspectral imaging: characterization of a noninvasive, in vivo system for determining tissue perfusion.
abstract: We characterize a visible reflectance hyperspectral imaging system for noninvasive, in vivo, quantitative analysis of human tissue in a clinical environment. The subject area is illuminated with a quartz-tungsten-halogen light source, and the reflected light is spectrally discriminated by a liquid crystal tunable filter (LCTF) and imaged onto a silicon charge-coupled device detector. The LCTF is continuously tunable within its useful visible spectral range (525-725 nm) with an average spectral full width at half-height bandwidth of 0.38 nm and an average transmittance of 10.0%. A standard resolution target placed 5.5 ft from the system results in a field of view with a 17-cm diameter and an optimal spatial resolution of 0.45 mm. The measured reflectance spectra are quantified in terms of apparent absorbance and formatted as a hyperspectral image cube. As a clinical example, we examine a model of vascular dysfunction involving both ischemia and reactive hyperemia during tissue reperfusion. In this model, spectral images, based upon oxyhemoglobin and deoxyhemoblobin signals in the 525-645-nm region, are deconvoluted using a multivariate least-squares regression analysis to visualize the spatial distribution of the percentages of oxyhemoglobin and deoxyhemoglobin in specific skin tissue areas.
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Karel J
authors.initials: KJ
authors.lastname: Zuzak
authors.forename: Michael D
authors.initials: MD
authors.lastname: Schaeberle
authors.forename: E Neil
authors.initials: EN
authors.lastname: Lewis
authors.forename: Ira W
authors.initials: IW
authors.lastname: Levin
mesh_terms: D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation / Q000379:methods*; D019719:Diagnostic Equipment; D004912:Erythrocytes / Q000737:chemistry; D006225:Hand / Q000098:blood supply; D006422:Hemerythrin / Q000031:analogs & derivatives* / Q000032:analysis; D006801:Humans; D006940:Hyperemia / Q000097:blood / Q000175:diagnosis; D007091:Image Processing, Computer-Assisted; D007511:Ischemia / Q000097:blood / Q000175:diagnosis; D008955:Models, Cardiovascular; D010108:Oxyhemoglobins / Q000032:analysis*; D015424:Reperfusion; D013057:Spectrum Analysis
chemical_list: D006422:Hemerythrin; D010108:Oxyhemoglobins; C043119:deoxyhemerythrin