Cardiovascular Imaging Technique Combines Optical Methods to Assess Plaque Structure, Prevent Heart Attacks and Strokes

Coronary artery disease remains the leading cause of death worldwide. In its most severe form, plaque erosion or rupture leads to the formation of blood clots, which can result in a myocardial infarction. Preventing coronary artery disease requires knowledge of the underlying details of atherosclerotic plaque.

(Photo: Wikimedia Commons/ Manu5)

Understanding Plaque Formation

When cholesterol, fats, and other substances accumulate in the walls of arteries, these vessels can thicken or harden, a condition known as atherosclerosis. If an atherosclerotic plaque inside the artery ruptures, a heart attack or stroke may occur.

Most of what experts know about the development of atherosclerosis comes from histopathology studies of coronary specimens from dead bodies. Plaque formation and evolution, however, are dynamic processes that involve a complex interplay of various factors.

Because of this, better clinical management is needed to help cardiologists tailor treatments and develop new therapies against atherosclerosis. This can be achieved with the aid of advanced intravascular imaging tools that can provide more accurate information.

Imaging systems like intravascular ultrasound and intravascular OCT make studying plaques in living patients possible. However, there is still a need for enhanced methods and tools for investigating and characterizing atherosclerosis. Hybrid imaging modalities that can assess biochemical and morphological plaque features can address this.

Catheter-Based Imaging Technique

In a recent study, researchers have developed a novel device for imaging dangerous plaques that can build up inside the coronary arteries. The flexible tool combines fluorescence lifetime imaging (FLIM) and polarization-sensitive optical coherence tomography (PSOCT) to gather information about atherosclerotic plaques' morphology, composition, and microstructure. The details of their work are discussed in the paper "Dual modality intravascular catheter system combining pulse-sampling fluorescence lifetime imaging and polarization-sensitive optical coherence tomography."

The experts focused on developing and validating multi-spectral FLIM as an intravascular imaging modality. They combined it with PSOCT to provide high-resolution morphological data, birefringence, and depolarization measurements. When used together, FLIM and PSOCT offered unprecedented information on plaque's biochemical composition, microstructure, and morphology.

FLIM and PSOCT must be combined into a single device without compromising the performance of either modality. To achieve high PSOCT performance, the research team used a rotary collimator with high light throughput and a high return loss. The catheter-based device they developed has dimensions and flexibility similar to the intravascular imaging tool currently used in clinical settings.

The experts tested the new system with artificial tissue to demonstrate basic functionality on well-characterized samples. The device can measure the properties of a healthy coronary artery taken from a pig. In vivo testing in swine hearts revealed that the performance of the hybrid catheter system was sufficient to support clinical validation.

The team plans to use the intravascular imaging system to study plaques in ex vivo human coronary arteries. The optical signals taken from the system will be compared with plaque characteristics identified by expert pathologists. This way, the experts can better understand the features identified by FLIM-PSOCT and use this information to design prediction models.