Intravascular Polarimetry: Clinical Translation and Future Applications of Catheter-Based Polarization Sensitive Optical Frequency Domain Imaging

Abstract

Optical coherence tomography (OCT) and optical frequency domain imaging (OFDI) visualize the coronary artery wall and plaque morphology in great detail. The advent of these high-resolution intracoronary imaging modalities has propelled our understanding of coronary atherosclerosis and provided enhanced guidance for percutaneous coronary intervention. Yet, the lack of contrast between distinct tissue types and plaque compositions impedes further elucidation of the complex mechanisms that contribute to acute coronary syndrome (ACS) and hinders the prospective identification of plaques susceptible to rupture. Intravascular polarimetry with polarization-sensitive OFDI measures polarization properties of the coronary arterial wall using conventional intravascular imaging catheters. The quantitative polarization metrics display notable image contrast between several relevant coronary plaque microstructures that are difficult to identify with conventional OCT and OFDI. Tissues rich in collagen and smooth muscle cells exhibit birefringence, while lipid and macrophages cause depolarization. In this review, we describe the basic principles of intravascular polarimetry, discuss the interpretation of the polarization signatures, and outline promising avenues for future research and clinical implications.

Automated Coronary Optical Coherence Tomography Feature Extraction with Application to Three-Dimensional Reconstruction

“…The complementary capabilities of these two imaging modalities have already demonstrated their potential to increase positive predictive capability when detecting TCFA [ 215 ]. Developments in OCT also show promise for providing useful histopathological information, with PS-OCT [ 108 ] demonstrating incremental value in the segmentation of artery layers and the outer wall [ 110 ]. Furthermore, molecular information obtained from multi-modal imaging could assist in automatically segmenting emerging vulnerable features, such as layered plaques, indicative of previously destabilized plaque that has since healed, or collagen arrangement within the fibrous cap, which could suggest lesion instability [ 216 , 217 ].…”

“…By extracting further information on vascular tissue components through polarization-sensitive OCT (PS-OCT) [ 107 , 108 , 109 ], Haft-Javaherian et al, were able to detect the lumen, intima and medial layers with impressive absolute distance errors of 2.36 ± 3.88 µm, 6.89 ± 9.99 µm and 7.53 ± 8.64 µm, respectively ( Figure 6 ) [ 110 ]. Comparisons between the automated approach (blue) and expert annotation (red) showed strong ability to handle many difficult, yet common, features observed in OCT pullbacks.…”

Carotid Artery Stiffness: Imaging Techniques and Impact on Cerebrovascular Disease

“…The exact relationship between arterial stiffness and the development of atherosclerotic plaque is a topic of considerable interest given that a more complete understanding of plaque formation may open new avenues for treating carotid atherosclerosis. This complex association may be more fully elucidated with the help of newer imaging technologies, such as optical coherence tomography, which allows for in vivo characterization of plaque as well as collagen and smooth muscle cells (26)(27)(28)(29). This technology and others may help in furthering our mechanistic understanding of arterial stiffness.…”

Coronary Computed Tomography Angiography Assessment of High-Risk Plaques in Predicting Acute Coronary Syndrome

“…In addition to CCTA, positron emission tomography (PET), magnetic resonance coronary angiography (MRCA), IVUS, OCT, and other imaging modalities are also effective methods to assess coronary atherosclerotic plaques (92)(93)(94)(95)(96)(97)(98). Notably, CCTA has irreplaceable advantages over other examinations.…”

“…However, there still remain certain drawbacks in CCTA. Compared with IVUS and OCT (92)(93)(94)(95)(96)(97)(98), CCTA has relatively lower spatial resolution, which hindered the detection of microscopic structure in histology (9,104), such as the fibrous cap thickness or plaque rupture. Further CCTA studies are needed to investigate pathophysiology of rapid progression of high-risk coronary plaques leading to ACS, which will offer clinical utility on the management of patients with CAD.…”