Comparing Raman and fluorescence lifetime spectroscopy from human atherosclerotic lesions using a bimodal probe

Abstract

Fluorescence lifetime imaging (FLIm) and Raman spectroscopy are two promising methods to support morphological intravascular imaging techniques with chemical contrast. Both approaches are complementary and may also be used in combination with OCT / IVUS to add chemical specificity to these morphologic intravascular imaging modalities. In this contribution, both modalities were simultaneously acquired from two human coronary specimens using a bimodal probe. A previously trained SVM model was used to interpret the fluorescence lifetime data; integrated band intensities displayed in RGB false color images were used to interpret the Raman data. Both modalities demonstrate unique strengths and weaknesses and these will be discussed in comparison to histologic analyses from the two coronary arteries imaged.

Raman imaging of macrophages incubated with triglyceride-enriched oxLDL visualizes translocation of lipids between endocytic vesicles and lipid droplets

“…Optical techniques are often focused on investigating the composition and vulnerability of plaques (20)(21)(22). But for the characterization of early plaque development, the cellular level of lipid metabolism is also of foremost interest.…”

Current Advances in the Diagnostic Imaging of Atherosclerosis: Insights into the Pathophysiology of Vulnerable Plaque

“…The advantage of combining these imaging modalities is to complement FLIM, an intravascular surface imaging technique, with high molecular specificity data from Raman, which is able to distinguish between calcifications, cholesterol, or carotenoids. The study also suggested that this bimodal probe can be combined with OCT/IVUS, adding chemical specificity to these morphologic intravascular imaging methods [91]. The recent animal study also indicated potential applications of combined OCT-Raman spectroscopy technique for chemical analysis of plaque lipid depositions, including triglycerides as the major component [92].…”

“…Moreover, the employment of Raman spectroscopy-FLIM bimodal probe demonstrated high chemical specificity in detecting plaque components in human coronary specimens [91]. The advantage of combining these imaging modalities is to complement FLIM, an intravascular surface imaging technique, with high molecular specificity data from Raman, which is able to distinguish between calcifications, cholesterol, or carotenoids.…”

In-vivo Raman spectroscopy: from basics to applications

“…Both modalities were simultaneously acquired from two human coronary specimens using a bimodal probe. 135 Raman spectroscopy could distinguish lipid from necrotic cores, whereas FLIM extracted information could identify fibrous caps.…”