Comprehensive Assessment of High-Risk Plaques by Dual-Modal Imaging Catheter in Coronary Artery

Macrophage-mannose-receptor-targeted photoactivatable agent for in vivo imaging and treatment of atherosclerosis

Previous studies have demonstrated the effects of theranostic agents on atherosclerotic plaques. However, there is limited information on targeted theranostics for photodynamic treatment of atherosclerosis. This study aimed to develop a macrophage-mannose-receptor-targeted photoactivatable nanoagent that regulates atherosclerosis and to evaluate its efficacy as well as safety in atherosclerotic mice. We synthesised and characterised D-mannosamine (MAN)-polyethylene glycol (PEG)-chlorin e6 (Ce6) for phototheranostic treatment of atherosclerosis. The diagnostic and therapeutic effects of MAN-PEG-Ce6 were investigated using the atherosclerotic mouse model. The hydrophobic Ce6 photosensitiser was surrounded by the hydrophilic MAN-PEG outer shell of the self-assembled nanostructure under aqueous conditions. The MAN-PEG-Ce6 was specifically internalised in macrophage-derived foam cells through receptor-mediated endocytosis. After laser irradiation, the MAN-PEG-Ce6 markedly increased singlet oxygen generation. Intravital imaging and immunohistochemistry analyses verified MAN-PEG-Ce6's specificity to plaque macrophages and its notable anti-inflammatory impact by effectively reducing mannose-receptor-positive macrophages. The toxicity assay showed that MAN-PEG-Ce6 had negligible effects on the biochemical profile and structural damage in the skin and organs. Targeted photoactivation with MAN-PEG-Ce6 thus has the potential to rapidly reduce macrophage-derived inflammatory responses in atheroma and present favourable toxicity profiles, making it a promising approach for both imaging and treatment of atherosclerosis.

Dual modality intravascular catheter system combining pulse-sampling fluorescence lifetime imaging and polarization-sensitive optical coherence tomography

The clinical management of coronary artery disease and the prevention of acute coronary syndromes require knowledge of the underlying atherosclerotic plaque pathobiology. Hybrid imaging modalities capable of comprehensive assessment of biochemical and morphological plaques features can address this need. Here we report the first implementation of an intravascular catheter system combining fluorescence lifetime imaging (FLIm) with polarization-sensitive optical coherence tomography (PSOCT). This system provides multi-scale assessment of plaque structure and composition via high spatial resolution morphology from OCT, polarimetry-derived tissue microstructure, and biochemical composition from FLIm, without requiring any molecular contrast agent. This result was achieved with a low profile (2.7 Fr) double-clad fiber (DCF) catheter and high speed (100 fps B-scan rate, 40 mm/s pullback speed) console. Use of a DCF and broadband rotary junction required extensive optimization to mitigate the reduction in OCT performance originating from additional reflections and multipath artifacts. This challenge was addressed by the development of a broad-band (UV-visible-IR), high return loss (47 dB) rotary junction. We demonstrate in phantoms, ex vivo swine coronary specimens and in vivo swine heart (percutaneous coronary access) that the FLIm-PSOCT catheter system can simultaneously acquire co-registered FLIm data over four distinct spectral bands (380/20 nm, 400/20 nm, 452/45 nm, 540/45 nm) and PSOCT backscattered intensity, birefringence, and depolarization. The unique ability to collect complementary information from tissue (e.g., morphology, extracellular matrix composition, inflammation) with a device suitable for percutaneous coronary intervention offers new opportunities for cardiovascular research and clinical diagnosis.

Feasibility and safety of non-contrast optical coherence tomography imaging using hydroxyethyl starch in coronary arteries

Intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition. Alternative flushing media needs to be investigated to reduce the risk of contrast-induced renal dysfunction. We investigated the feasibility and safety of pentastarch (hydroxyethyl starch) for clinical OCT imaging. We prospectively enrolled 43 patients with 70 coronary lesions (46-stented; 24-native). Total 81 OCT pullback pairs were obtained by manual injection of iodine contrast, followed by pentastarch. Each pullback was assessed frame-by-frame using an automated customized lumen contour/stent strut segmentation algorithm. Paired images were compared for the clear image segments (CIS), blood-flushing capability, and quantitative morphometric measurements. Overall image quality, as assessed by the proportion of CIS, was comparable between the contrast- and pentastarch-flushed images (97.1% vs. 96.5%; p = 0.160). The pixel-based blood-flushing capability was similar between the groups (0.951 [0.947-0.953] vs. 0.950 [0.948-0.952], p = 0.125). Quantitative two- and three-dimensional morphometric measurements of the paired images correlated well (p < 0.001) with excellent inter-measurement variability. All patients safely underwent OCT imaging using pentastarch without resulting in clinically relevant complications or renal deterioration. Non-contrast OCT imaging using pentastarch is clinically safe and technically feasible with excellent image quality and could be a promising alternative strategy for patients at high risk of renal impairment.

Intravascular Ultrasound and Optical Coherent Tomography Combined Catheter

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are established intravascular imaging tools for evaluating plaque characteristics and volume, together with guiding percutaneous coronary interventions. The high tissue penetration of IVUS facilitates assessment of the entire vessel wall, whereas the higher resolution of OCT allows detailed assessment of endoluminal structures. A combined IVUS-OCT probe works synergistically, facilitating a greater understanding of de novo coronary artery disease and a better correlation with pathological specimens. In this review, we discuss the rationale and potential roles of the combined IVUS-OCT catheter system.

Histological classification of atherosclerotic arteries using high-speed confocal Raman microscopy with machine learning

Confocal Raman microscopy is a useful tool to observe composition and constitution of label-free samples at high spatial resolution. However, accurate characterization of microstructure of tissue and its application in diagnostic imaging are challenging due to weak Raman scattering signal and complex chemical composition of tissue. We have developed a method to improve imaging speed, diffraction efficiency, and spectral resolution of confocal Raman microscopy. In addition to the novel imaging technique, the machine learning method enables confocal Raman microscopy to visualize accurate histology of tissue sections. Here, we have demonstrated the performance of the proposed method by measuring histological classification of atherosclerotic arteries and compared the histological confocal Raman images with the conventional staining method. Our new confocal Raman microscopy enables us to comprehend the structure and biochemical composition of tissue and diagnose the buildup of atherosclerotic plaques in the arterial wall without labeling.

Global research trends in in-stent neoatherosclerosis: A CiteSpace-based visual analysis

BACKGROUND

Recent studies have shown that in-stent neoatherosclerosis (ISNA/NA) is an important cause of late stent failure. A comprehensive understanding of the current state of research in this field will facilitate the analysis of its development trends and hot frontiers. However, no bibliometric correlation has been reported yet. Here, we analyze the relevant literature since the emergence of the concept and provide valuable insights.

METHODS

Publications were collected from the Web of Science Core Collection (WoSCC) and PubMed. Microsoft Excel, SPSS and CiteSpace were used to analyze and present the data.

RESULTS

A total of 498 articles were collected, with Japan and Cardiovasc Res Fdn being the main publishing forces in all country/region and institutions. J AM COLL CARDIOL is the journal with the most published and co-cited articles. According to co-citation analysis, optical coherence tomography, thrombosis, implantation, restenosis, drug-eluting stent, and bare metal stent have become more and more popular recently.

CONCLUSION

ISNA is a niche and emerging field. How to reduce the incidence of ISNA and improve the late patency rate of coronary stents may remain a hot spot for future research. The pathogenesis of ISNA also needs to be explored in more depth.