Research and Clinical Applications of Optical Coherence Tomography in Invasive Cardiology: A Review

In cardiology, optical coherence tomography (OCT) is an invasive imaging technique based on the principle of light coherence. This system was developed to obtain three-dimensional high resolution images to examine coronary artery normal and/or pathological structure. This technique replaces the ultrasound used by its main alternative procedure, intravascular ultrasound, by a near-infrared light source. Acute coronary syndromes due to atherosclerotic vascular disease are the leading cause of mortality in developed and developing countries. As a consequence, intravascular imaging systems became an important area of research and 1991 marks the first use of OCT in coronary artery observations. Since its first appearance in invasive cardiology, OCT maintains a strong presence in the research environments for the identification of vulnerable plaques, as it is able to overcome difficulties presented by other techniques such as virtual intravascular ultrasound, near-infrared spectroscopy, and histology. Moreover, OCT is increasingly being used in the clinical practice as a guide during coronary interventions and in the assessment of vascular response after coronary stent implantation. This review focuses on the relevance of OCT in research and clinical applications in the field of invasive cardiology and discusses the future directions of the field.     

Optical Coherence Tomography Angiography in Diabetes

Diabetic retinopathy is a progressive microvascular disease that leads to increased vessel permeability, retinal ischemia, and retinal neovascularization. Optical coherence tomography angiography (OCTA) is a novel angiography technique that has the capability to advance our understanding of diabetic eye disease by providing high-resolution images of retinal and choroidal microvasculature blood flow and structure. Using OCTA, the vascular changes of diabetic retinopathy including microaneurysms, retinal non-perfusion, intraretinal microvascular abnormalities, and neovascularization can be clearly visualized. OCTA offers several advantages over fluorescein angiography (FA) in that it is faster, safer, and non-invasive, allows better visualization of retinal vessels in both the superficial and deep capillary layers, and can provide quantitative measurements of areas of non-perfusion of the macula and nerve. OCTA capillary perfusion density maps and average perfusion density values provide an easy way to grade progressive vascular change. Despite these advantages, imaging with OCTA can only provide a limited view of the peripheral retina and is unable to demonstrate leakage, staining, or pooling. OCTA requires patients to maintain good fixation to obtain high-resolution images which can be a challenge for those with severe macular disease. In patients who cannot safely undergo FA, OCTA may serve as an alternative form of angiography that can be safely and more frequently performed for the management of diabetic retinopathy.     

The Clinical Atlas of Intravascular Optical Coherence Tomography for iPad

The first comprehensive educational tool devoted exclusively to intravascular OCT is now available from PCR publishing.     

Predictors of Rapid Plaque Progression: An Optical Coherence Tomography Study

ObjectivesThis study sought to identify morphological predictors of rapid plaque progression.BackgroundTwo patterns of plaque progression have been described: slow linear progression and rapid step-wise progression. The former pattern will cause stable angina when the narrowing reaches a critical threshold, whereas the latter pattern may lead to acute coronary syndromes or sudden cardiac death.MethodsPatients who underwent optical coherence tomography (OCT) imaging during the index procedure and follow-up angiography with a minimum interval of 6 months were selected. Nonculprit lesions with a diameter stenosis of ≥30% on index angiography were assessed. Lesion progression was defined as a decrease of angiographic minimum lumen diameter ≥0.4 mm at follow-up (mean, 7.1 months). Baseline morphological characteristics of plaques with rapid progression were evaluated by OCT. In a subgroup with follow-up OCT imaging for plaques with rapid progression, morphological changes from baseline to follow-up were assessed.ResultsAmong 517 lesions in 248 patients, 50 lesions showed rapid progression. These lesions had a significantly higher prevalence of lipid-rich plaque (76.0% vs. 50.5%, respectively), thin-cap fibroatheroma (TCFA) (20.0% vs. 5.8%, respectively), layered plaque (60.0% vs. 34.0%, respectively), macrophage accumulation (62.0% vs. 42.4%, respectively), microvessel (46.0% vs. 29.1%, respectively), plaque rupture (12.0% vs. 4.7%, respectively), and thrombus (6.0% vs. 1.1%, respectively) at baseline compared with those without rapid progression. Multivariate analysis identified lipid-rich plaque (odds ratio [OR]: 2.17; 95% confidence interval [CI]: 1.02 to 4.62; p = 0.045]), TCFA (OR: 5.85; 95% CI: 2.01 to 17.03; p = 0.001), and layered plaque (OR: 2.19; 95% CI: 1.03 to 4.17; p = 0.040) as predictors of subsequent rapid lesion progression. In a subgroup analysis for plaques with rapid progression, a new layer was detected in 25 of 41 plaques (61.0%) at follow-up.ConclusionsLipid-rich plaques, TCFA, and layered plaques were predictors of subsequent rapid plaque progression. A new layer, a signature of previous plaque disruption and healing, was detected in more than half of the lesions with rapid progression at follow-up. (Massachusetts General Hospital Optical Coherence Tomography Registry; NCT01110538)     

血管内光学干涉断层成像在老年冠脉临界病变诊疗中的应用

尽管多种无创性冠脉影像诊断方法以及冠脉造影已经成为现代冠心病诊疗的重要手段,但是在决定冠脉临界病变程度、是否需要进行介入治疗、以及早期识别易损斑块和准确评价支架植入即刻和远期效果等方面仍然存在很多困难与争议。血管内光学干涉断层成像在管腔狭窄程度、范围以及斑块性质的显示方面有不可比拟的优势,其组织分辨率大约较IVUS高10倍,近似病理组织学程度,但是其在老年冠心病人中的应用极少。本文综述冠脉临界病变的影像诊断进展,以有助于危险评估、治疗决策,最终促进介入治疗的合理应用。     

光学相干断层成像在冠状动脉粥样硬化性心脏病的临床应用进展

光学相干断层成像是一种利用光学原理的血管内成像新技术,具有高分辨率及良好的组织相关性,对于识别冠状动脉内不同斑块具有很重要的意义,现就其在冠状动脉粥样硬化性心脏病的诊断及治疗中的应用做一综述。     

心肌桥的光学相干断层成像诊断及临床意义

目的研究心肌桥（myocardial bridge,MB）在光学相干断层成像（optical coherence tomography,OCT）中的形态特征以及与动脉硬化的关系。方法对常规冠状动脉造影（coronary angiography,CAG）过程中发现的12例MB患者（男7例,女5例;年龄58.07±12.08岁）进行OCT检查,观察MB的位置、长度以及MB近段2cm血管有无内膜增厚和斑块,并准确测量。结果共发现MB12处,均位于左前降支（LAD）中远段。OCT与CAG测得MB长度对比为20.5±4.2mm比15.6±3.5mm（P〈0.01）,两者测得最窄处面积狭窄百分率为48.7%±4.8%比55.3%±2.6%（P〈0.05）。所有MB段和远段冠状动脉内未发现明显粥样硬化斑块,MB近段2cm内冠状动脉段均发现不同程度内膜增厚（0.64±0.23mm）。结论OCT能清楚显示MB的活体结构及形态特征,操作安全。MB近段冠状动脉内膜均有不同程度增生。     

Impact of Diabetes Mellitus on Vascular Healing Process After Everolimus-Eluting Stent Implantation: An Optical Coherence Tomography Study

Background/purposeTo study the impact of diabetes mellitus (DM) on vascular healing process after implantation of everolimus-eluting stent (EES).Methods/materialsData from 3 prospective studies (HEAL-EES, REVER, and RESERVOIR), including patients with EES implantation and OCT follow-up, were merged. Differences in vascular healing process assessed by OCT were compared between DM and non-DM using generalized estimating equations. Neointimal proliferation, neointimal signal pattern (high, low, and layered), and uncovered/malapposed struts were evaluated.ResultsA total of 96 lesions (61 DM lesions and 35 non-DM lesions) were included. Mean OCT follow-up time was 8.9 ± 1.5 months and comparable between groups. DM were older, high frequently female and acute coronary syndrome, and received smaller stent than non-DM. No differences were observed in quantitative vascular healing process between groups. However, DM exhibited higher low and layered signal pattern neointima compared to non-DM at lesion level (p = 0.030) and cross-section level (p < 0.001). Uncovered/malapposed struts were comparable between groups.ConclusionsQuantitative vascular healing process was comparable between groups. However, DM was significantly associated with low signal pattern, which is characteristic of focal inflammation, after EES implantation. Further study might be required to study relationship between neointimal signal pattern and clinical events.     

Optical Coherence Tomography of the Coronary Arteries

Intravascular imaging, particularly optical coherence tomography, has brought significant improvement in diagnostic and therapeutical approaches to coronary artery disease and has offered superior high-resolution visualization of coronary arteries. The ability to obtain images of intramural and transmural coronary structures allows the study of the process of atherosclerosis, effect of therapies, mechanism of acute coronary syndrome and stent failure, and performance of new devices and enables the interventional cardiologist to optimize the effect of percutaneous coronary intervention. In this review, we provide the summary of the latest published data on clinical use of optical coherence tomography as well as practical algorithm for optical coherence tomography-guided percutaneous coronary intervention for daily interventional practice.     

Optical Biopsy in Human Pancreatobiliary Tissue Using Optical Coherence Tomography

Optical coherence tomography (OCT) is a newtechnique for performing high-resolution,cross-sectional tomographic imaging in human tissue. OCTis analogous to ultrasound B mode imaging except that ituses light rather than acoustical waves. As aresult, OCT has over 10 times the resolution ofcurrently available clinical high-resolutioncross-sectional imaging technologies. In this work, weinvestigate the capability of OCT to differentiate thearchitectural morphology of pancreatobiliary tissues.Normal pancreatobiliary tissues, including thegallbladder, common bile duct, pancreatic duct, andpancreas were taken postmortem and imaged using OCT. Imageswere compared to corresponding histology to confirmtissue identity. Microstructure was delineated indifferent tissues, including tissue layers, glands,submucosal microvasculature, and pancreatic islets ofLangerhans. The ability of OCT to providehigh-resolution imaging of pancreatobiliaryarchitectural morphology suggests the feasibility ofusing OCT as a powerful diagnostic endoscopic imaging technology toimage early stages of pancreatobiliarydisease.