Intracoronary Near-Infrared Spectroscopy (NIRS) Imaging for Detection of Lipid Content of Coronary Plaques: Current Experience and Future Perspectives

Abstract

Acute coronary syndromes are frequently caused by “vulnerable” coronary plaques with a lipid-rich core. In 1993 near-infrared spectroscopy (NIRS) was first used to detect the lipid (cholesterol) content of atherosclerotic plaques in an experimental animal study. NIRS was then carefully validated using human atherosclerotic plaques (ex vivo), and has subsequently been developed for intracoronary imaging in humans, for which now an FDA-approved catheter-based NIRS system is available. NIRS provides a “chemogram” of the coronary artery wall and is used to detect lipid-rich plaques. Using this technology, recent studies have shown that lipid-rich plaques are very frequent in the culprit lesion of patients with an acute coronary syndrome, and are also common in non-culprit coronary lesions in these patients as compared to patients with stable coronary disease. First studies are evaluating the impact of statin therapy on coronary NIRS-detected lipid cores. Intracoronary NIRS imaging represents a highly interesting method for coronary plaque characterization in humans and may become a valuable tool for the development of novel therapies aiming to impact on the biology of human coronary artery plaques, likely in combination with other intracoronary imaging techniques, such as optical coherence tomography.

Autofluorescence and infrared fundus imaging for detection of retinal emboli and unmasking undiagnosed systemic abnormalities

“…[56] In Case 3, there was the clinical suspicion of a small calcium or cholesterol embolus as it did not appear like a fibrinoplatelet embolus. Lack of hyperautofluorescence ruled out the possibility of any calcific embolus.…”

Intracoronary Imaging in the Detection of Vulnerable Plaques

“…NIRS is a recently developed imaging modality, first tested in vivo in humans in 2001, and is developed for clinical applications over the past decade [ 64 , 65 ]. NIRS uses a catheter-mounted core of optical fibres to emit and receive diffuse reflectance near-infrared light ( λ o = 0.8–2.5 μm) [ 66 , 67 ]. Similar to OCT, the NIRS catheter contains an optical fibre which rotates (240 rotations min −1 ) to acquire an image and is mounted on an automated pullback device.…”

Systems Biology and Noninvasive Imaging of Atherosclerosis

“…For example, transesophageal US was recently employed in mongrel dogs to quantify changes in aortic area and elastic properties from velocity-vector imaging (VVI) with aging 80 . Another study used a combination of multi-vessel IVUS and novel near infra-red spectroscopy (NIRS) 81, 82 to evaluate features of vulnerability in fibroatheromas of diabetic/hypercholesterolemic pigs 83 . Longitudinally, IVUS demonstrated a progressive increase in plaque and media areas, with the appearance of necrotic cores and regions of positive vascular remodeling.…”