Intravascular photoacoustic and optical coherence tomography imaging dual-mode system for detecting spontaneous coronary artery dissection: A feasibility study

In this work,we present an intravascular dual-mode endoscopic system capable of both intravascular photoacoustic imaging(IVPAI)and intravascular optical coherence tomography(IVOCT)for recognizing spontaneous coronary artery dissection(SCAD)phantoms.IVPAI provides high-resolution and high-penetration images of intramural hematoma(IMH)at different depths,so it is especially useful for imaging deep blood clots associated with imaging phantoms.IVOCT can readily visualize the double-lumen morphology of blood vessel walls to identify intimal tears.We also demonstrate the capability of this dual-mode endoscopic system using mimicking phantoms and biological samples of blood clots in ex vivo porcine arteries.The results of the experiments indicate that the combined IVPAI and IVOCT technique has the potential to provide a more accurate SCAD assessment method for clinical applications.

Vascular Stress Analysis Based on in vivo Intravascular Optical Coherence Tomography Image Segmentation

Identification of carotid artery atherosclerosis is crucial for the diagnosis of the cerebral apoplexy and other vascular diseases.Intravascular optical tomography(IVOCT)has been employed to clinical coronary imaging for several years.Vessel morphological information on IVOCT images together with blood flow information on Doppler OCT(DOCT)images could provide a more accurate internal environment of arteries.Images integrated with fluid-structure interaction(FSI)could obtain the accurate mechanical responses and the quantitative material characters.A porcine carotid artery was imaged with an intravascular system(C7-XR,St.Jude Medical Inc.St.Paul,Minnesota,USA)in vivo,during which 120 images of one section and 600 images of a 5 mm/s pull back were captured within 6 s.Those images were then overlapped with Doppler phase changes to imply the changes in flow profiles.Segmentation and quantification of vessel structure was done in the software(MATLAB 2014b),including specifically the segmentation of lumen,imaging catheter,vessel wall and the guide wire.Appropriate interpolation functions are selected in the coordinate transformation algorithm to have smooth boundaries from images.A set of flow algorithms include image segmentation,three-dimensional/two-dimensional model reconstruction,inversion of material parameters,fitting of experimental velocity data and theoretical derivation based on simulation results is proposed.All steps are programmed to provide a theoretical basis for the future simplified process control.3D-reconstruction FSI model was built in SOLIDWORKS by lofting operation based on the segmentation results.Commercial finite element software(COMSOL 5.3,Sweden)numerically analyzed the entity model to obtain vessel stress/strain and flow shear stress data.Boundary conditions are from the OCT detection.Material of the artery was set to be the modified Mooney-Rivlin constitutive model and the parameters used were adjusted in an algorithm to match an ex vivo experiment.Wall shear stresses(WSS)and vessel deformations were chosen to measure the conditions of the artery and would serve as a target variables for future prediction.Thus,the geometric information together with the data of materials and other mechanical properties are possible to obtain during the imaging process.Segmentation process provided anatomically correct models of a two-layered artery.Numerical simulation permits reliable stress distribution in which the position of catheter and the artery curvature have a neglectable disturbance.Shear stress of the fluid is quite small compared with that of the wall at the same interface,which shows good agreement with the former studies.Moreover,a high flushing speed of 0.1 mps have little impact on the stress distributions and magnitudes,which denotes that the OCT imaging process brings little harm to the vessel.It is the first attempt to combine the OCT imaging and Doppler OCT within a full algorithm and a structural analysis.This study is helpful for the biomechanical property studies of carotid arteries and the development of medical imaging technology.

Pencil-beam scanning catheter for intracoronary optical coherence tomography

Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to control beam profiles,but the spacer length should be well controlled to obtain desired beam profiles and thus it sets an obstacle in mass catheter fabrication.Besides,although GRIN lens with large gradient constant can provide tight focus spot,it has short depth of focus and fast-expanded beam which leads to poor lateral resolution for deep tissue.In this paper,a type of spacer-removed probe is demonstrated with a small gradient constant GRIN lens.This design simplifies the fabrica-tion process and is suitable for mass production.The output beam of the catheter is a narrow nearly collimated light beam,referred to as pencil beam here.The full width at half maximum beam size varies from 35.1μm to 75.3μm in air over 3-mm range.Probe design principles are elaborated with probe/catheter fabrication and performance test.The in vivo imaging of the catheter was verified by a clinical ICOCT system.Those results prove that this novel pencil-beam scanning catheter is potentially a good choice for ICOCT systems.

基于深度学习的冠状动脉IVOCT图像中易损斑块识别算法研究进展

介绍了冠状动脉血管内光学相干断层成像(intravascular optical coherence tomography,IVOCT)图像中易损斑块的智能识别算法的研究现状,分析了传统机器学习算法在易损斑块识别领域的不足及深度学习算法的优势。从斑块分类、检测、分割3个方面阐述了基于深度学习的斑块识别网络的结构特征及针对性的结构改进方法,指出了现有基于深度学习的识别算法的局限性,提出了提升识别精度、理解易损斑块破裂机理是该领域的未来发展方向。

基于Transformer的结构强化IVOCT导丝伪影去除方法

为去除导丝伪影以提高血管内光学相干断层扫描(IVOCT)的图像质量,辅助医师更加准确地诊断心血管疾病,降低误诊及漏诊的概率,针对IVOCT图像结构信息复杂且伪影区域占比大的难点,提出一种采用生成对抗网络(GAN)架构的基于Transformer的结构强化网络(SETN)。首先,GAN的生成器在提取纹理特征的原始图像(ORI)主干生成网络的基础上,并联了RTV(Relative Total Variation)图像强化生成网络用于获取图像的结构信息;其次,在ORI/RTV图像的伪影区域重建过程中,引入了分别关注时/空间域信息的Transformer编码器,用于捕获IVOCT图像序列的上下文信息以及纹理/结构特征之间的关联性;最后,利用结构特征融合模块将不同层次的结构特征融入ORI主干生成网络的解码阶段,配合判别器完成导丝伪影区域的图像重建。实验结果表明,SETN的导丝伪影去除结果在纹理和结构的重建上均十分优秀。此外,导丝伪影去除后IVOCT图像质量的提高,对于IVOCT图像的易损斑块分割及管腔轮廓线提取任务均具有积极意义。

Multimodal intravascular imaging technology for characterization of atherosclerosis

Early detection of vulnerable plaques is the critical step in the prevention of acute coronary events.Morphology,composition,and mechanical property of a coronary artery have been demonstrated to be the key characteristics for the identification of vulnerable plaques.Several intravascular multimodal imaging technologies providing co-registered simultaneous images have been developed and applied in clinical studies to improve the characterization of atherosclerosis.In this paper,the authors review the present system and probe designs of representative intra-vascular multimodal techniques.In addition,the scientific innovations,potential limitations,and future directions of these technologies are also discussed.

支架术后即刻冠状动脉光学相干断层扫描结果的临床影响

冠状动脉光学相干断层扫描的分辨率为10μm,它可为术者提供支架贴壁不良、组织脱垂、支架内血栓和支架边缘夹层等支架术后即刻结果,但其对临床预后的影响一直存在争议。现总结既往研究,并就支架术后即刻冠状动脉光学相干断层扫描结果的研究进展及临床影响进行综述。

Neointimal coverage of sirolimus-eluting stents 6 months and 12 months after implantation： evaluation by optical coherence tomography

Optical coherence tomography （OCT） is a new imaging modality with resolution of approximately 10 pm and can be employed to visualize intracoronary characteristics. Sirolimus-eluting stents （SES） are susceptible to late thrombosis due to delayed reendothelialization over the stent struts, which may result in acute myocardial infarction or death. This study was designed to evaluate the re-endothelialization and neointimal coverage of SES with OCT 6 months and 12 months after implantation.Methods A total of 36 patients enrolled in the study underwent OCT examination 6 months （17 patients） and 12 months （19 patients） after SES implantation, The strut apposition to the vessel wall and neointimal coverage on SES struts were evaluated by OCT, Results Forty-six SES and 6561 struts were analyzed, At 6 months, 3041 struts （98.7%） were well-apposed and 39 struts （1,3%） were malapposed, At 12 months, 3434 struts （98,6%） were well-apposed and 47 struts （1,4%） were malapposed, Furthermore, only 4 SES at 6 months （18,2%） and 10 SES at 12 months （41,7%） were fully covered by neointimal growth, The average neointimal thicknesses covering the analyzed struts at 6 months and 12 months were （42±28） μm and （88±32） μm, respectively, There were 1989 struts at 6 months （72,1%） and 1461 struts at 12 months （45,6%） with neointimal thickness 〈100 μm, Conclusions OCT was able to visualize the strut apposition to the vessel wall and neointimal coverage on SES struts, At 6-month and 12-month follow-up examinations most struts were covered with thin neointima, but few of the entire SES showed full coverage. To prevent late-stent thrombosis in the presence of uncovered stent struts, longer dual antiplatelet drugs therapy should be recommended,

基于影像的冠状动脉生理学功能评估研究进展

血流储备分数(FFR)已经成为评估冠状动脉狭窄程度、指导血运重建策略以及选择治疗方案的冠状动脉生理学“金标准”。然而,由于FFR评估过程中存在压力导丝侵入性操作、充血药物的使用等诸多因素,其在临床实践中的应用受到限制。随着冠状动脉虚拟生理学的应用,基于冠状动脉影像衍生FFR的技术得以研发,如冠状动脉造影衍生FFR、光学相干断层成像(OCT)衍生的FFR以及血管内超声(IVUS)衍生的FFR。同时这些功能学评估手段的诊断效能不断被大量临床研究证实。本文旨在对基于冠状动脉造影、IVUS和OCT衍生的FFR的诊断效能、临床运用等方面进行综述。

Bioresorbable stent unloading during percutaneous coronary intervention:Early detection and management

In this letter,we comment on a recent case report by Sun et al in the World Journal of Cardiology.The report describes the successful management of a rare complication:The unloading or detachment of a bioresorbable stent(BRS)during percutaneous coronary intervention(PCI)in a male patient.The unloading of BRS was detected via angiography and intravascular ultrasound(IVUS)imaging of the left coronary artery and left anterior descending artery.Although this case is interesting,the authors’report lacked crucial details.Specifically,insufficient information about the type of BRS used,potential causes of BRS unloading,or whether optical coherence tomography(OCT)imaging for coronary arteries was performed before,during,or after PCI.The OCT imaging of coronary arteries before PCI can potentially prevent BRS unloading due to its higher resolution compared to IVUS.In addition,despite detecting myocardial bridging during the PCI,the authors did not provide any details regarding this variation.Here we discuss the various types of BRS,the importance of OCT in PCI,and the clinical relevance of myocardial bridging.

光学相干断层成像技术在经皮冠状动脉血管内冲击波能量钙化碎裂术治疗冠状动脉钙化斑块中应用的研究进展

冠状动脉钙化病变会增加介入手术的难度和并发症发生率,导致患者预后不良,在支架置入前对钙化斑块进行充分预处理将有效减少不良结局发生。经皮冠状动脉血管内冲击波能量钙化碎裂术(IVL)能有效破坏钙化斑块,从而有利于支架输送和促进支架膨胀完全。光学相干断层成像(OCT)可准确识别钙化病变,评估钙化斑块经IVL预处理效果,指导介入手术策略制定。本文将综合近年来此领域研究进展,总结OCT在IVL治疗冠状动脉钙化病变中的作用。

血管腔内超声在下肢动脉疾病中的应用现状与进展

下肢动脉粥样硬化性疾病是临床上较常见的一种周围动脉疾病。目前临床常用的影像学诊断方法主要有超声、计算机断层扫描和动脉造影术等,但这些手段仅能观察到下肢动脉形态学改变,对于动脉腔内病变的评估(如粥样斑块的性质)具有一定的局限性。随着血管腔内超声(Intravascular Ultrasound,IVUS)技术的逐渐成熟以及对下肢动脉粥样硬化性疾病发病机制研究的不断深入,IVUS为临床诊疗方法的选择提供了更好的帮助。本文对IVUS在辅助诊断下肢动脉粥样硬化性疾病中的最新应用进展进行综述,以期促进IVUS技术在临床的应用。

光学相关断层摄影技术观察壁冠状动脉的可行性研究

目的 讨论光学相关断层摄影技术观察壁冠状动脉的可行性。方法 选择36名心肌桥（myocardial bridging,MB）患者（即冠脉造影可见“挤奶现象”的患者）行光学相干断层摄影检查（optical coherence tomography,OCT）及血管内超声检查（intravascular ultrasound,IVUS）,并进一步用猪的心脏作为动物模型以确认与OCT图像相对应的组织学结构。结果 所有患者OCT检测均发现MB节段内一紧邻动脉管壁外的边界清晰、不均质的、低信号梭形区域;且在舒张期更易观察到这一特征性的图像表现。该梭形区域的最大弧度为176.3°±53.1°（106°~287.5°）,最大厚度为（0.41±0.12）mm（0.25~0.69 mm）。所有患者均在且只在肌桥节段外近段血管内检出动脉粥样硬化改变,仅1例患者在肌桥节段内发现了管壁内膜增厚。OCT所发现的梭形区域不同于IVUS图像中代表MB肌束的半月形无回声区域。另外,线性相关分析发现梭形区域弧度与管腔受压迫程度呈负相关（r=-0.403,P=0.004）。进一步的动物模型的组织学检查结果发现这一梭形、低信号区域是位于肌肉与动脉血管之间的结缔组织。结论 在造影和IVUS确诊的MB患者中,OCT检查可在肌桥节段发现一紧邻动脉管壁外的边界清晰、不均质的、低信号梭形区域,进一步组织学检查结果发现这一区域为动脉周围结缔组织,而非IVUS中代表肌束的半月形无回声区域。

血管内光学相干成像技术检测易损斑块研究进展

动脉粥样硬化斑块破裂引发血栓形成是临床急性冠脉综合征的根本原因。易损斑块的早期识别与及时处理是避免临床心血管事件的关键。目前已经有很多影像学方法应用于冠脉内易损斑块的检测,但易损斑块的形态学及其破裂导致血栓形成的机制仍是临床医生关注的重点。血管内光学相干成像技术(OCT)是一种基于心脏导管的检查方法,它利用近红外光,可获取高达10μm分辨率的影像,从而在细胞水平实现体内血管壁微结构成像。随着新一代频域OCT(FD-OCT)的发展,这一技术在易损斑块研究中发挥积极作用。现将OCT在易损斑块相关研究中的进展作一综述。

腔内影像技术指导下的PCI精准治疗策略研究进展

腔内影像学作为三维成像,较二维的冠状动脉造影更能准确地反映血管腔内结构及识别病变斑块的性质,因此有助于介入术前支架或球囊类型和置入部位的选择,指导不同类型病变合理的预处理方式,并证实可以优化左主干及慢性完全性闭塞病变介入治疗的策略,最终减少并发症及不良事件的发生。本综述从国内外循证医学证据和指南的角度,介绍了冠脉介入治疗腔内影像学研究在优化经皮冠状动脉介入治疗中的最新进展。

应用血管内超声/光学相干断层成像杂交技术研究冠状动脉钙化与斑块回缩的关系

目的:冠状动脉钙化是否与斑块回缩相关尚不清楚。本研究的目的是结合光学相干断层扫描(OCT)和血管内超声(IVUS)评估冠状动脉钙化和斑块回缩(PS)之间的关系。方法:15例患者,16支血管纳入本研究,术后即刻和术后5年联合应用OCT和IVUS评估钙化斑块面积变化和斑块回缩,及二者之间的关系。IVUS检测管腔面积(LA)、血管面积(VA)和斑块/中膜面积(PA)。将斑块/中层回缩(PS)定义为PA相对减少>5%。OCT检测钙化面积、钙化弧度和钙化长度。结果:术后即刻和5年随访时,共有72个OCT和IVUS完全匹配的横断面(共432个图)纳入该研究。72个横截面中,35个横截面在5年随访时显示为PS,37个横截面为非PS。斑块面积的变化分别与OCT测量的钙化面积变化呈负相关(r=-0.29,P=0.004),与OCT钙化弧度变化(r=-0.42,P<0.001),OCT钙化长度变化(r=-0.5,P<0.001)呈负相关,与IVUS测量的钙化弧度变化呈负相关(r=-0.31,P=0.024),而与管腔面积变化呈正相关(r=0.24,P=0.044)。结论:冠状动脉钙化斑块进展使得斑块回缩和管腔扩大。应用IVUS/OCT杂交技术能更好的评估钙化斑块进展和斑块回缩之间的相关性。

光学相干成像与血管内超声在冠状动脉左主干介入治疗中的应用价值比较

目的比较光学相干成像（OCT）与血管内超声（IVUS）在左主干介入治疗中的应用价值。方法回顾性选取2012年4月至2013年12月因左主干病变在首都医科大学附属北京安贞医院行介入治疗的患者60例。根据患者在左主干介入治疗中使用的血管内影像指导方法分为IVUS组（29例）和OCT组（31例），比较2组患者造影及介入治疗结果和随访12个月后的预后，包括死亡、心肌梗死和靶病变再次血运重建等主要心血管不良事件。结果OCT组患者造影剂用量、后扩张次数和贴壁不良反应发生率均明显高于IVUS组[（187±29）ml比（155±20）ml、（3．5±0．3）次比（2．3±0．6）次、77．4％（24／31）比51．7％（15／29）]，差异均有统计学意义（均P〈0．01）。随访12个月后，2组患者病死率、心肌梗死发生率、靶病变再次血运重建发生率比较，差异均无统计学意义（均P〉0．05）。结论与IVUS相比，OCT可发现更多支架贴壁不良反应，增加了后扩张次数，但并未明显改善预后。

植入药物洗脱支架后晚期获得性贴壁不良的情况

目的用光学相干断层成像(optical coherence tomography,OCT)及血管内超声(intravascular ultrasound,IVUS)观察患者植入药物洗脱支架(drug-eluting stent,DES)后1年获得性贴壁不良发生情况,并分析发生机制。方法入选30例植入DES的冠心病患者,分别于术后即刻及术后1年对患者行OCT及IVUS检查。对获得的OCT及IVUS图像进行测量,分析术后1年获得性贴壁不良的发生率,并对比分析术后即刻及术后1年的影像数据,找出发生获得性贴壁不良可能的原因及预后。结果术后1年时对27例患者的32枚DES行OCT及IVUS检查。术后1年时共4枚(12.5%)支架出现获得性贴壁不良,其中贴壁不良处未覆盖的小梁数为12(11.8%),贴壁良好处未覆盖的小梁数为184(3.0%),两者之间有统计学差异(P<0.05);而贴壁不良处新生内膜厚度及新生内膜面积与贴壁良好处两者之间无统计学差异(P>0.05);用IVUS测得术后1年时贴壁不良处的外弹力板面积为(28.1±2.7)mm2,较术后即刻外弹力板面积为(22.9±2.9)mm2明显增大,两者间有统计学差异(P<0.01)。32枚支架均为发现支架内血栓形成。结论用OCT及IVUS可检测出支架术后获得性贴壁不良,获得性贴壁不良可能与支架术后血管正性重构相关。发生获得性贴壁不良的位置有更多的支架小梁未被新生内膜覆盖,可能需延长双重抗血小板治疗时间。

应用血管内超声与光学相干断层扫描杂交融合分析冠状动脉支架置入后钙化斑块进展情况和前体组织成分

目的探讨灰阶血管内超声(IVUS)、IVUS-虚拟组织学(VH)和光学相干断层扫描(OCT)评估接受生物可吸收支架置入患者从基线到5年随访钙化斑块进展情况和前体组织成分分析。方法选取首都医科大学附属北京安贞医院接受生物可吸收支架置入的急性冠状动脉综合征患者15例(共16个病灶)。利用解剖标志和不透射线标志融合OCT和IVUS图像,并匹配基线和5年随访图像。以杂交融合诊断的钙化灶为金标准,评估IVUS和OCT诊断钙化的敏感度、特异度和一致性,分析OCT和IVUS-VH检测的主要钙化前体组织成分,比较5年后支架内外钙化灶的钙化面积和钙化弧度与术后即刻的变化。结果灰阶IVUS、IVUS-VH和OCT图像和随访匹配最终入选72对融合横断面,5年随访时发现46个钙化灶,其中24个(52.2%)为钙化进展,22个(47.8%)为新生钙化。OCT分析46个钙化灶主要前体组织成分为脂质(33个,71.2%),IVUS-VH分析主要前体组织成分为坏死核心(34个,73.9%)。5年后,OCT检测支架内和支架外钙化面积均高于术后即刻(均P<0.05)。结论通过使用OCT和IVUS融合成像发现,置入生物可吸收支架患者5年随访普遍出现钙化进展,OCT和IVUS-VH检测钙化灶主要前体组织成分分别为脂质和坏死核心。

无导丝虚拟血流储备分数技术在稳定性冠心病介入治疗中的指导价值

欧洲和中国冠心病介入治疗指南均以最高级别推荐对稳定性冠心病(SCAD)患者采用血流储备分数(FFR)进行冠状动脉病变的功能学评估并指导血运重建。然而,由于FFR存在价格昂贵、血管扩张药引起患者不适等缺点,导致其难以在临床普及。基于影像计算的多种无导丝/无腺苷的FFR技术应运而生,无导丝虚拟FFR技术具有廉价、快捷、方便的优势,有望大幅拓展冠状动脉病变功能学评估的临床应用。现就冠状动脉病变功能学评估的价值及目前面临的挑战,现有无导丝虚拟FFR技术各自的优缺点,无创冠状动脉生理学检查的发展方向进行综述,以期阐明无导丝虚拟FFR在SCAD患者血运重建中的指导价值、存在的局限性及未来研究改进的方向。