Researchers from Cedars-Sinai Medical Center had developed a device that will use light emissions from body tissues to detect the inflammation that is part of plaque formation in the condition of atherosclerosis.
Now, in a study involving laboratory rabbits, a device that stimulates, collects and measures light emissions from body tissues has been able to detect the presence of inflammatory cells that are associated with critical atherosclerotic plaques in humans - plaques that are vulnerable to rupture. The study is described in the August 2005 issue of the journal Atherosclerosis.
Recent atherosclerosis research has found that the composition of plaque and its "vulnerability" to rupture may be more significant than the degree of arterial blockage as a precursor to heart attack and stroke. The lining (intima) of a normal artery consists of several thin layers of cells and connective tissue. Segments containing stable atherosclerotic plaque become thickened with collagen while sections of vulnerable plaque are infiltrated by macrophages. In humans, the inflammatory process weakens the plaque's thin, fibrous cap, often leading to rupture of the plaque and blockage of blood vessels.
An experimental time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) device developed by researchers at Cedars-Sinai Medical Center was used to detect the presence of inflammatory cells in the aortas of animals, with results compared to those from pathology studies.
Laser-induced fluorescence spectroscopy is based on the fact that when molecules in cells are stimulated by light, they respond by becoming excited and re-emitting light of varying colors. Just as a prism splits white light into a full spectrum of color, laser light focused on tissues is re-emitted in colors that are determined by the properties of the molecules. When these emissions are collected and analyzed (fluorescence spectroscopy), they provide information about the molecular and biochemical status of the tissue.
Time resolution adds a greater degree of specificity, measuring not only the wavelength of the emission but the time that molecules remain in the excited state before returning to the ground state. This information is valuable because some emissions overlap on the light spectrum but have different "decay" characteristics.