Coronary atherosclerotic plaque characterization using IVUS elastography and Raman spectroscopy

The composition of atherosclerotic lesions is considered to be an important determinant for the development of acute coronary ischemic syndromes. We investigated the potentials of a combination of intravascular ultrasound (IVUS) elastography and intravascular near infrared Raman spectroscopy, to assess the geometry and physical and chemical composition of normal vessel wall and plaque. Intact human coronary arteries were mounted in an in vitro pressurized perfusion setup. At selected cross-sections, two echo-frames were acquired at different intraluminal pressures to obtain elastograms. Subsequently, Raman spectra were acquired in 30 seconds at four different angles using a sideways viewing Raman catheter. Spectra were modeled to extract quantitative chemical information. Calcified areas were identifiable on the echograms, elastograms and Raman spectra. A combination of geometric information provided by the echogram, chemical information as obtained with Raman spectroscopy, and high stress regions determined by the elastogram, may prove to be valuable for identification of vulnerable plaques in vivo.