SBIR-STTR Award

Atherosclerosis is the leading cause of death in industrialized countries, worldwide. In the United States, myocardial infarctions, almost entirely attributable to coronary artery atherosclerosis, account for 20 to 25% of all deaths. Therapies are available, but no reliable methods can predict in advance which lesions will progress. One major reason is that in situ biopsies of blood vessels is difficult and risky, so histopathology cannot be used routinely to provide information about the state of diseased vessels. A substantial literature of in vitro studies show that fluorescence spectroscopy of arterial walls can distinguish between normal, atherosclerotic and calcified atherosclerotic plaque. Few successful in vivo studies have been done, however, for several reasons. One reason is the lack of a suitable optical probe. Another reason is that hemoglobin absorption often distorts the fluorescence signatures to the point where they cannot be properly analyzed. NLI proposes to address these limitations by designing, fabricating and testing a new side-looking optical probe which will measure, in vivo, both fluorescence and reflectance from arterial tissue. From these two measurements intrinsic fluorescence spectra, undistorted by scattering and absorption processes can be obtained, which will greatly improve the reliability of the optical diagnosis.

Thesaurus Terms:
atherosclerotic plaque, biomedical equipment development, cardiovascular disorder diagnosis, diagnosis design /evaluation, fluorescence spectrometry, fluorescent dye /probe, optics

Published studies indicate that visible wavelength reflectance and fluorescence spectroscopy are each promising techniques for clinically recognizing vulnerable plaque (VP) - a condition prone to rupture and produce arterial thrombosis. Reflectance is already visually accessible in normal angioscopy, and yellow lipid may be seen diffusely through an otherwise white fibrous cap, depending on its thickness, and form a qualitative indication for VP. Progress toward a clinically useful instrument for recognizing VP by quantified spectroscopy requires an arterial, optical-fiber based side-looking probe (SLP). It is a primary goal of the Phase-2 program to accomplish this by building on the Phase-1 tissue-probe-spectroscopy modeling, probe construction techniques developed, and probe - tissue measurements obtained. In the Phase-2 program three SLP designs will be produced and clinically tested in peripheral arteries. The data will be reduced to provide spectrally resolved diffuse reflectance and intrinsic fluorescence. Comparison will be made to results from concurrent Monte Carlo modeling, results from pathology, and results from the measurements of others with respect to characterizing the tissue and recognizing lesions with thin fibrous caps with a significant lipid core - hallmarks of VP. We expect that bringing together the colorimetry information with intrinsic fluorescence will produce results better than either alone.

Thesaurus Terms:
angiography, atherosclerotic plaque, biomedical equipment development, cardiovascular disorder diagnosis, fluorescence spectrometry, reflection spectrometry, venous thrombosis cardiovascular imaging /visualization, clinical biomedical equipment, diagnosis quality /standard, peripheral blood vessel bioengineering /biomedical engineering, clinical research, colorimetry, fiber optics, human subject, videotape /videodisc