Abstract 2779: Two- Dimentional Imaging Of Lipids Deposited In The Coronary Plaques By Near-infrared Fluorescence Angioscopy
Background: The lipids deposited deep in the vascular wall are hardly detectable by any available imaging modalities including IVUS and OCT. Since near-infrared (NIR) light penetrates relatively deeply into the tissues, we devised a near-infrared fluorescence angioscope (NIRFA) for two dimensional imaging of lipids deposited even in deep layers of vascular wall.
Aim: To examine feasibility of NIRFA for imaging of lipids in coronary arterial wall in man.
Methods: NIRFA is composed of a quartz fiberscope incorporated in 5F balloon catheter, fluorescence exciter, fluorescence emitter, ICCD and recorder. NIR exciter filter of 710nm and emitter filter of 780nm were employed since among the major 30 substances composing atherosclerotic plaques, free cholesterol and cholesteryl esters alone exhibit NIR autofluorescence while oxLDL and TG not.
In vitro study: Coronary artery removed from human cadaver was perfused with saline and an angioscope was introduced into it for imaging of lipids and the obtained NIR images were compared with histology.
Clinical study: During routine coronary angiography, lipid deposition in the coronary artery was surveyed by NIRFA in 7 patients with coronary artery disease.
In vitro study. Coronary segments without lipid deposition by histology did not exhibit autofluorescence. Those with lipid deposition by histology, the lipids deposited within 700μm in depth from luminal surface exhibited autofluorescence. Deposited lipids not forming lipid pool exhibited strong and homogenous autofluorescence. Lipid pool exhibited no or weak autofluorescence surrounded by strong ones, indicating it is filled with oxLDL and/or TG.
Clinical study. Autofluorescence was frequently detected not only in yellow plaques but also in white plaques by conventional angioscopy and hard plaques by IVUS.
Also, autofluorescence was frequently detected in apparently normal coronary segments.
Conclusion: The results indicate that this NIRFA is feasible for two dimensional imaging of lipids deposited even in deep layers of coronary arterial wall which are not detectable by conventional angioscopy, OCT and IVUS.