Abstract

Tissue specimens obtained from a normal healthy aorta and from a plaque damaged aortal portion were sliced to a thickness of ∼10 μm. They were washed thoroughly with a saline solution to remove traces of hemoglobin and had a neutral grayish-white appearance with no evident chromophores. The samples were supported between CaF₂ plates while being measured. Transmittance (7) measurements were performed over the 300–2500-nm spectral region by placing the samples in the entrance port of an integrating sphere reflectometer, an arrangement that captured all the forward scattered beam. The specimens were placed next in an integrating sphere with center-mounted sample and the combined transmittance plus reflectance (T + R) of each was measured over the same wavelength range. The measured absorptance [A = 1− (T + R)] spectra of both normal tissue and tissue containing plaque revealed no discrete absorption features in the 250-700-nm region. In general, absorptance increased toward shorter wavelengths and the greatest difference between the absorptance of normal aortal tissue and plaque occurred in the 250–350-nm region. These results indicate that laser angioplasty may be improved by the use of UV lasers that operate in the 250–350-nm region and can interact more strongly with plaque than with the surrounding arterial wall.

© 1985 Optical Society of America