The average depth of blood vessels in a cutaneous site, either normal or diseased, can be specified by a simple rapid noninvasive optical measurement. An optical fiber spectrophotometer delivers white light via optical fibers to a skin site. The light reflected by tissue scattering and successfully collected by optical fibers is carried to a diode array spectrophotometer for spectral analysis. The reflectance spectrum is analyzed to specify the component of the optical density (OD) spectrum which is attributed to the cutaneous blood. Then the ratio of the OD_{420 nm}/OD_{585 nm} provides a quantitative indication of the average depth of the blood in the skin site. The purple light (420 nm) less easily penetrates the skin to sample the cutaneous blood content than does the yellow light (585 nm). The calibration of the measurement was accomplished by Monte Carlo simulations of measurements on skin with a layer of blood at various depths. In a study of 47 neonates, the amount of blood content ranged from 4 - 12 mg hemoglobin/g tissue (equivalent to 0.8 - 2.4% of the skin volume being whole blood), and the average depth of blood ranged from 250 - 425 micrometers .

Date Published: 7 September 1994
PDF: 7 pages
Proc. SPIE 2128, Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV, (7 September 1994); doi: 10.1117/12.184904

Published in SPIE Proceedings Vol. 2128:
Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV
R. Rox Anderson M.D.; R. Rox Anderson M.D., Editor(s)