Optical Coherence Tomography: Potential Clinical Applications

Optical coherence tomography (OCT) is a novel intravascular imaging modality using near-infrared light. By OCT it is possible to obtain high-resolution cross-sectional images of the vascular wall structure and assess the acute and long-term effects of percutaneous coronary intervention. For the time being OCT has been mainly used in research providing new insights into the pathophysiology of the atheromatic plaque and of the vascular response to stenting, however, it seems that there is potential for clinical application of OCT in various fields, such as pre-interventional evaluation of coronary arteries, procedural guidance in coronary interventions, and follow-up assessment of vascular healing after stent implantation. This review will focus on the potential and advantages of OCT in the clinical practice of a catheterization laboratory.     

光学相干断层扫描诊断黄斑部视网膜前膜的评价

目的　探讨黄斑部视网膜前膜的光学相干断层扫描 (OCT)图像特征及临床应用价值。方法　对特发性黄斑前膜 9例和继发性黄斑前膜 13例患者进行经黄斑中心凹的OCT线性扫描并测量膜厚度。结果　OCT图像能清晰显示与视网膜分离或部分分离的前膜 13例 ,并可显示与视网膜紧密粘连的前膜及其对视网膜的牵拉形态改变。结论　OCT能直接客观地显示黄斑前膜横断面特征及其与玻璃体视网膜的关系并能提供定量的分析。     

Optical Coherence Tomography in Assessing Plaque Characteristics

Optical coherence tomography (OCT), a new imaging modality, has shown a superior ability in detecting and distinguishing different types of plaques (fibrous, fibrocalcific, and lipid-rich plaques), in visualizing of vascular microstructures such as intraluminal thrombi, vascular dissection, and structure of restenotic tissues, and finally in identifying vulnerable plaques, otherwise missed by intravascular ultrasound. However, limitations in the use of OCT such as poor penetration and its attenuation by blood or the clinical relevance of OCT should be clarified through further investigation, and careful attention should be paid to the future studies on OCT.     

视网膜前膜光学相干断层扫描图像分析

目的探讨光学相干断层扫描（OCT）检查对黄斑区视网膜前膜临床诊断和术后的评估价值。方法对在我院眼底检查拟诊或诊断为黄斑区视网膜前膜的49例患者（61眼）术前及术后进行OCT检查。结果黄斑区视网膜前膜的OCT图像表现为视网膜表面厚薄不一的高反光带，部分视网膜内表面完全紧密粘连，大部分与视网膜内层分离，多数为黄斑中心凹变浅，厚度增加，部分可伴黄斑假性裂孔、板层裂孔、黄斑囊样水肿或视网膜神经上皮脱离。术后黄斑区视网膜前膜消失，部分黄斑区神经上皮损害或黄斑部不同程度水肿。结论OCT检查可直接客观显示黄斑区前膜及术后黄斑区视网膜组织结构的改变。     

Recent Advances in the Field of Optical Coherence Tomography

Purpose of Review

The scope of this text is to critically review the most important recent advances in the field of optical coherence tomography, both from a clinical, scientific, and technical point of view.

Recent Findings

In recent years, important steps forward have been put in the field of optimization of PCI (with a focus on optimal sizing of stents and optimization of stent expansion after implantation) and the differentiation and its possible applications of various underlying morphologic characteristics of acute coronary syndrome lesions. Several efforts have been made to elucidate underlying mechanical causes of stent thrombosis, based on optical coherence tomography (OCT) imaging. This had led to the recognition of neoatherosclerosis as an important cause for very late stent thrombosis, fueling new research into this area and to the development of intracoronary devices which could be even more safe for patients on the very long term.

Summary

With an ever increasing use for clinical and scientific applications in coronary artery disease, OCT has come to a mature and solid tool in the armamentarium of the coronary artery disease specialist. With new areas deserving more intensified focus and several innovations ahead, it seems that OCT is there to defend its position as the standard intracoronary imaging modality for the next decennium.

     

外伤性黄斑病变光学相干断层成像的应用研究

目的探讨光学相干断层成像（OCT）在外伤性黄斑病变中应用的临床意义。方法对56例外伤性黄斑病变（56眼）行OCT检查,并进行图像分析。结果OCT检查显示全层黄斑孔23眼、板层黄斑孔3眼、黄斑前膜3眼、黄斑区出血8眼、神经上皮浆液性脱离5眼、出血性色素上皮脱离各4眼、黄斑水肿4眼、黄斑区神经上皮层变薄6眼。结论OCT在外伤性黄斑病变的鉴别诊断、病情监测及对其发病机制的分析研究等方面均有重要的应用价值。     

光学相干断层扫描在青光眼早期诊断中的应用价值

目的探讨频域光学相干断层扫描(OCT)对发现和诊断早期青光眼的应用价值。方法将84例(160眼)行眼底视乳头OCT检查的患者按检查结果分为3组:疑似青光眼组(SG组,34例,68眼)、确诊青光眼早中期组(DG早中期组,40例,72眼)和正常组(10例,20只眼)。分别对各组采集的各象限(颞侧、上方、鼻侧、下方)视神经纤维层(RNFL)厚度、平均RNFL、视盘参数(水平及垂直杯盘比、杯/盘面积比)的数据进行比较;将OCT测得的各组眼的平均RNFL厚度值与视野平均缺损(MD)进行直线相关性分析。结果 SG组下方、上方象限及平均RNFL厚度,DG早中期组下方、上方、鼻侧、颞侧象限及平均RNFL厚度均明显低于正常组(均P<0.05);SG组鼻侧、颞侧RNFL厚度与正常组比较差异均无统计学意义(均P>0.05)。DG早中期组各象限(上方、下方、鼻侧)及平均RNFL厚度明显低于SG组(均P<0.05);颞侧RNFL厚度比较差异无统计学意义(P>0.05)。DG早中期组及SG组的水平及垂直杯盘比、杯/盘面积较正常组明显变大(均P<0.05)。各组的平均RNFL厚度值与MD呈高度正相关(r=0.703,P=0.00)。结论频域OCT能直观、精确地以图像及数据的方式显示视神经病变的微观层面,能检测出视野损害前的早期青光眼RNFL局限性损害,具有简便、非侵入性、重复性好、可长期随访等特点,有利于对青光眼患者的早期诊断。     

光学相干断层成像术检测视网膜厚度的误差研究

目的:探讨光学相干断层成像术(OCT)检测视网膜厚度的误差并对误差原因进行分析。方法:在1个月内随机5次对38例自愿者(共76眼)采用OTC进行视网膜神经上皮层厚度检测,测量结果采用"重复测量回归分析"方法进行统计分析。结果:各位点测量值的类内相关系数(ICC值)在0.53～0.72之间(均大于0.5),表明采用OCT测量视网膜厚度具有良好的可重复性;但各象限点视网膜厚度的ICC值略有差异,产生这些差异除了与OCT仪器的固有因素有关外,还与受检者的依从性等因素相关。结论:OCT是一种可靠的视网膜厚度定量检测工具,但还需克服诸多不利因素以提高检测的精确度。     

重度非增生型糖尿病视网膜病变多焦视网膜电图与光学相干断层扫描的图像特征及临床意义

[目的]观察重度非增生型糖尿病视网膜病变（NPDR）的多焦视网膜电图（mfERG） 及视网膜光学相干断层扫描（OCT）的图像特征及临床意义.[方法]对临床确诊的重度NPDR 患者组20例（25只眼）和正常对照组20例（20只眼） 进行mfERG与OCT检查,并对所得数据进行统计分析.[结果]重度NPDR患者组mfERG 2-5环的反应密度均低于正常对照组,且有显著性差异（P〈0.05）,N1波潜伏期在4环、P1波潜伏期在3~5环与正常对照组相比显著延长（P〈0.05）.重度NPDR患者组OCT显示视网膜黄斑中心凹厚度平均值高于正常对照组,差异有统计学意义.[结论]MfERG可有效地评价重度NPDR患者黄斑区视网膜的功能,重度NPDR患者OCT断层扫描像与其已知的视网膜病变特点相一致.     

光学相干断层成像检查术应用于冠心病患者的护理

目的探讨光学相干断层成像术(optical coherence tomography,OCT)应用于冠心病患者的护理方法。方法回顾并总结64例接受OCT检查的冠心病患者的临床资料。结果 64例患者均成功完成OCT检查,检查过程中有18例(28.1%)患者出现轻度胸闷和心电图T波改变;26例(40.6%)患者心电图出现变化但无胸闷症状,血流恢复后心电图恢复到检查前水平;20例(31.3%)患者无不适感及心电图变化。结论精心、细致的护理配合对患者顺利完成OCT检查具有重要意义。     

中心性浆液性脉络膜视网膜病变的谱域光学相干断层扫描特征

  目的  观察中心性浆液性脉络膜视网膜病变(central serous chorioretinopathy, CSC)的谱域光学相干断层扫描(spectral domain optical coherence tomography, SD-OCT)图像特征。  方法  对临床上已确诊为CSC的34例(40只眼)患者进行SD-OCT和荧光素眼底血管造影(fundus fluorescein angiography, FFA)检查, 分析其图像特征并对二者结果进行比较。  结果  40只眼的SD-OCT检查结果显示, 37只眼(92.5%)有黄斑区局限性神经上皮脱离, 3只眼(7.5%)仅有色素上皮脱离。神经上皮脱离的37只眼中, 9只眼(24.3%)感光细胞内外节结合部信号增强、增厚, 28只眼(75.7%)信号减弱或消失; 伴有色素上皮脱离20只眼(54.1%), 伴有色素上皮层增厚、不规则或隆起12只眼(32.4%), 仅有神经上皮脱离5只眼(13.5%)。3只眼SD-OCT与FFA均表现为色素上皮脱离者, 二者色素上皮脱离位置和大小相一致。28只眼FFA表现为荧光渗漏点者, SD-OCT在相应位置均有色素上皮增厚、不规则、隆起或脱离。SD-OCT较FFA能发现更多的色素上皮脱离和神经上皮脱离。  结论  CSC患者的SD-OCT多数在神经上皮脱离区内存在视网膜色素上皮的增厚、不规则、隆起或脱离, 感光细胞内外节结合部信号多数减弱或消失。     

Optical Coherence Tomography: A Noninvasive Method to Assess Wound Reepithelialization

Background Accurate assessment of wound healing may require invasive tissue biopsies, limiting its clinical usefulness in humans. Optical coherence tomography (OCT) is a novel, high‐resolution method using light reflection to obtain noninvasive cross sectional imaging of biological tissues. Objectives To evaluate the utility of OCT for assessing wound reepithelialization in a porcine model. Methods The authors conducted an animal study with two domestic pigs. Excisional cutaneous wounds were created over the ventral surface of the animals using an electric dermatome set at a depth of 600 μm. The wounds were excised two or three days later and precisely marked to guide initial OCT and subsequent tissue slicing and microscopy. Comparing hematoxylin and eosin–stained histologic sections and the corresponding OCT images from each tissue sample permitted identification of the correlative micromorphology. Scatter and Bland–Altman plots were used to present the data. The primary measure of agreement was the standard deviation of the pairwise differences in percent reepithelialization between OCT and histology together with a 95% confidence interval. Results In normal skin, the epidermis was characterized by a thin, bright layer indicating a high degree of light scattering on OCT. The dermis below was characterized by a thicker, darker area indicating less scattering of light. All fresh excisional wounds lacked an outer bright layer of epidermis immediately after injury. At days 2 and 3, the wounds were partially reepithelialized. A new bright layer with intense light scattering was present on OCT corresponding to the neoepidermis on hematoxylin and eosin–stained sections. The correlation between percent reepithelialization measured with OCT and histology was 0.66 (p < 0.001), and the standard deviation of the differences was 11.0% (95% confidence interval = 8.4% to 16.1%). Conclusions OCT accurately detects the presence or absence of the epidermal layer of skin, allowing noninvasive tracking of wound reepithelialization.     

Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography

Quantification of chromophore concentrations in reflectance mode remains a major challenge for biomedical optics. Spectroscopic Optical Coherence Tomography (SOCT) provides depth-resolved spectroscopic information necessary for quantitative analysis of chromophores, like hemoglobin, but conventional SOCT analysis methods are applicable only to well-defined specular reflections, which may be absent in highly scattering biological tissue. Here, by fitting of the dynamic scattering signal spectrum in the OCT angiogram using a forward model of light propagation, we quantitatively determine hemoglobin concentrations directly. Importantly, this methodology enables mapping of both oxygen saturation and total hemoglobin concentration, or alternatively, oxyhemoglobin and deoxyhemoglobin concentration, simultaneously. Quantification was verified by ex vivo blood measurements at various pO₂ and hematocrit levels. Imaging results from the rodent brain and retina are presented. Confounds including noise and scattering, as well as potential clinical applications, are discussed.OCIS codes: (110.4500) Optical coherence tomography, (170.3880) Medical and biological imaging     

Depth-resolved imaging and detection of micro-retroreflectors within biological tissue using Optical Coherence Tomography

A new approach to in vivo biosensor design is introduced, based on the use of an implantable micron-sized retroreflector-based platform and non-invasive imaging of its surface reflectivity by Optical Coherence Tomography (OCT). The possibility of using OCT for the depth-resolved imaging and detection of micro-retroreflectors in highly turbid media, including tissue, is demonstrated. The maximum imaging depth for the detection of the micro-retroreflector-based platform within the surrounding media was found to be 0.91 mm for porcine tissue and 1.65 mm for whole milk. With further development, it may be possible to utilize OCT and micro-retroreflectors as a tool for continuous monitoring of analytes in the subcutaneous tissue.