Quantitative evaluation of atherosclerotic plaque phantom by near-infrared multispectral imaging with three wavelengths

Abstract

Atherosclerosis is a primary cause of critical ischemic disease. The risk of critical event is involved the content of lipid in unstable plaque. Near-infrared (NIR) range is effective for diagnosis of atherosclerotic plaque because of the absorption peaks of lipid. NIR multispectral imaging (NIR-MSI) is suitable for the evaluation of plaque because it can provide spectroscopic information and spatial image quickly with a simple measurement system. The purpose of this study is to evaluate the lipid concentrations in plaque phantoms quantitatively with a NIR-MSI system. A NIR-MSI system was constructed with a supercontinuum light, a grating spectrometer and a MCT camera. Plaque phantoms with different concentrations of lipid were prepared by mixing bovine fat and a biological soft tissue model to mimic the different stages of unstable plaque. We evaluated the phantoms by the NIR-MSI system with three wavelengths in the band at 1200 nm. Multispectral images were processed by spectral angle mapper method. As a result, the lipid areas of phantoms were effectively highlighted by using three wavelengths. In addition, the concentrations of lipid areas were classified according to the similarity between measured spectra and a reference spectrum. These results suggested the possibility of image enhancement and quantitative evaluation of lipid in unstable plaque with a NIR-MSI.