Takayuki Okamura

Optical coherence tomography patterns of stent restenosis

BACKGROUNDnStent restenosis is an infrequent but poorly understood clinical problem in the drug-eluting stent era. The aim of the study was to evaluate the morphologic characteristics of stent restenosis by optical coherence tomography (OCT).nnnMETHODSnPatients (n = 24, 25 vessels) presenting with angiographically documented stent restenosis were included. Quantitative OCT analysis consisted of lumen and stent area measurement and calculation of restenotic tissue area and burden. Qualitative restenotic tissue analysis included assessment of tissue structure, backscattering and symmetry, visible microvessels, lumen shape, and presence of intraluminal material.nnnRESULTSnBy angiography, restenosis was classified as diffuse, focal, and at the margins in 9, 11, and 5 vessels, respectively. By OCT, restenotic tissue structure was layered in 52%, homogeneous in 28%, and heterogeneous in 20%. The predominant backscatter was high in 72%. Microvessels were visible in 12%. Lumen shape was irregular in 28% and there was intraluminal material in 20%. The mean restenotic tissue symmetry ratio was 0.58 +/- 0.19. Heterogeneous and low scattering restenotic tissue was more frequent in focal (45.5% and 54.5%, respectively) than in diffuse (0 and 11.1%) and margin restenosis (0 and 0%) (P = .005 for heterogeneous, P = .03 for low scattering). Restenosis patients with unstable angina symptoms presented more frequently irregular lumen shape (60 vs 6.7%, P = .007). Stents implanted </=12 months ago had more frequently restenotic tissue with layered appearance (84.6% vs 16.7%, P = .003).nnnCONCLUSIONSnWe demonstrate the ability of OCT to identify differential patterns of restenotic tissue after stenting. This information could help in understanding the mechanism of stent restenosis.

Atherosclerotic tissue characterization in vivo by optical coherence tomography attenuation imaging

Optical coherence tomography (OCT) is rapidly becoming the method of choice for assessing arterial wall pathology in vivo. Atherosclerotic plaques can be diagnosed with high accuracy, including measurement of the thickness of fibrous caps, enabling an assessment of the risk of rupture. While the OCT image presents morphological information in highly resolved detail, it relies on interpretation of the images by trained readers for the identification of vessel wall components and tissue type. We present a framework to enable systematic and automatic classification of atherosclerotic plaque constituents, based on the optical attenuation coefficient mu(t) of the tissue. OCT images of 65 coronary artery segments in vitro, obtained from 14 vessels harvested at autopsy, are analyzed and correlated with histology. Vessel wall components can be distinguished based on their optical properties: necrotic core and macrophage infiltration exhibit strong attenuation, mu(t)>or=10 mm(-1), while calcific and fibrous tissue have a lower mu(t) approximately 2-5mm(-1). The algorithm is successfully applied to OCT patient data, demonstrating that the analysis can be used in a clinical setting and assist diagnostics of vessel wall pathology.

Optical Coherence Tomography Assessment Of The Acute Effects Of Stent Implantation On The Vessel Wall. A Systematic Quantitative Approach

Objective: To observe and characterise vessel injury after stenting using optical coherence tomography (OCT), to propose a systematic OCT classification for periprocedural vessel trauma, to evaluate its frequency in stable versus unstable patients and to assess its clinical impact during the hospitalisation period. Setting: Stenting causes vessel injury. Design and interventions: All consecutive patients in whom OCT was performed after stent implantation were included in the study. Qualitative and quantitative assessment of tissue prolapse, intra-stent dissection and edge dissection were performed. Results: Seventy-three patients (80 vessels) were analysed. Tissue prolapse within the stented segment was visible in 78/80 vessels (97.5%). Median number of tissue prolapse sites was 8 (IQR 4–19), mean (SD) area 1.04 (0.9) mm2. Intra-stent dissection flaps were visible in 69/80 vessels (86.3%) (median number 3 (IQR 1.25–6), maximum flap length 450 (220) μm). Fifty-five out of 80 vessels (68.8%) showed dissection cavities (median number 2 (IQR 0–4.75), maximum depth 340 (170) μm). Edge dissection was visible in 20 vessels (mean (SD) length flap 744 (439) μm). The frequency of tissue prolapse or intra-stent dissection was similar in stable and unstable patients (95.6% vs 100%, pu200a=u200a0.5 for tissue prolapse; 91.1% vs 82.9%, pu200a=u200a0.3 for intra-stent dissection). There were no events during the hospitalisation period. Conclusions: OCT allows a detailed visualisation of vessel injury after stent implantation and enables a systematic classification and quantification in vivo. In this study, frequency of tissue prolapse or intra-stent dissections after stenting was high, irrespective of the clinical presentation of the patients, and was not associated with clinical events during hospitalisation.

Quantitative Ex Vivo and In Vivo Comparison of Lumen Dimensions Measured by Optical Coherence Tomography and Intravascular Ultrasound in Human Coronary Arteries

INTRODUCTION AND OBJECTIVESnThe relationship between the lumen dimensions obtained in human coronary arteries using intravascular ultrasound (IVUS) and those obtained using optical coherence tomography (OCT) is not well understood. The objectives were to compare the lumen measurements obtained ex vivo in human coronary arteries using IVUS, OCT and histomorphometry, and in vivo in patients using IVUS and OCT with and without balloon occlusion.nnnMETHODSnEx vivo study: the lumen areas of matched anatomical sections of human coronary arteries were measured using IVUS, OCT and histology. In vivo study: the lumen areas in matched sections were measured using IVUS and OCT with and without occlusion.nnnRESULTSnEx vivo: in the eight specimens studied, the lumen area obtained using OCT and IVUS was larger than that obtained using histomorphometry: mean difference 0.8+/-1 mm(2) (28%) for OCT and 1.3+/-1.1 mm(2) (40%) for IVUS. In vivo: in the five vessels analyzed, the lumen area obtained using IVUS was larger than that obtained using OCT: mean difference 1.67+/-0.54 mm(2) (33.7%) for IVUS relative to OCT with occlusion and 1.11+/-0.53 mm(2) (21.5%) relative to OCT without occlusion. The lumen area obtained using OCT without occlusion was larger than that obtained using OCT with occlusion: mean difference 0.61+/-0.23 mm(2) (13%).nnnCONCLUSIONSnIn fixed human coronary arteries, both IVUS and OCT overestimated the lumen area compared with histomorphometry. In vivo the lumen dimensions obtained using IVUS were larger than those obtained using OCT, with or without occlusion. Moreover, the OCT image acquisition technique (i.e. with or without occlusion) also had an impact on lumen measurement.

Comparación cuantitativa ex vivo e in vivo de las dimensiones del lumen medidas por tomografía de coherencia óptica y ecografía intravascular en arterias coronarias humanas

Introduccion y objetivos La relacion entre las dimensiones del lumen medidas por ecografia intravascular (IVUS) y tomografia de coherencia optica (OCT) en arterias coronarias humanas no es bien conocida. Los objetivos son comparar las dimensiones del lumen en IVUS, OCT e histologia en arterias coronarias humanas ex vivo, y comparar in vivo las dimensiones del lumen obtenidas en pacientes con IVUS, OCT con oclusion y OCT sin oclusion. Metodos Estudio ex vivo: el area luminal se midio en secciones anatomicas correspondientes en IVUS, OCT e histologia en arterias coronarias humanas. Estudio in vivo: el area luminal se midio en regiones correspondientes en IVUS y OCT con y sin oclusion. Resultados Ex vivo: en las 8 muestras estudiadas, el area del lumen fue mas grande en IVUS y OCT que en histologia –diferencia media, 0,8xa0±xa01xa0mm2 (28%) para OCT y 1,3xa0±xa01,1xa0mm2 (40%) para IVUS–. In vivo: en los cinco vasos analizados las dimensiones del lumen fueron mas grandes en IVUS que en OCT –diferencia area media del lumen, 1,67xa0±xa00.54xa0mm2 (33,7%) para IVUS y OCT con oclusion y 1,11xa0±xa00.53xa0mm2 (21,5%) para IVUS y OCT sin oclusion–. Las dimensiones del lumen fueron mas grandes en OCT sin oclusion que en OCT con occlusion –diferencia media, 0,61xa0±xa00,23xa0mm2 (13%). Conclusiones En arterias coronarias humanas fijadas, IVUS y OCT sobrestimaron el area del lumen en comparacion con la histologia. In vivo, las dimensiones del lumen fueron mas grandes en IVUS que en OCT con o sin oclusion. La tecnica de adquisicion de OCT (con o sin oclusion) influye en las dimensiones del lumen.

Relation between plaque type and dissections at the edges after stent implantation: An optical coherence tomography study

BACKGROUNDnStent implantation can create vessel damage such as edge dissections. The objectives were i) to evaluate the frequency of edge dissections after stenting visible by intracoronary optical coherence tomography (OCT) in comparison with angiography. ii) to assess with OCT the plaque type left at the stent edges after implantation, and iii) to study whether there is an association between plaque type and dissections at stent edges.nnnMETHODSnSeventy-three consecutive patients (80 vessels) with OCT post-stent implantation were included in the study. By OCT, plaque type at stent edges and presence of edge dissection were assessed. Angiograms were analyzed by two independent observers to assess the presence of edge dissections.nnnRESULTSnDistal and proximal edges were visible by OCT in 72/80 and 45/80 vessels respectively. OCT and angiography agreed in the detection of 7 dissections at distal edge (κ=0.32) and 1 dissection at proximal edge (κ=0.22). Plaque type at distal edge was: fibrotic 55.6%, fibrocalcific 22.2%, fibroatheroma 15.3% and thin-cap fibroatheroma (TCFA) 6.9%. At proximal edge plaque type was: fibrotic 31.1%, fibrocalcific 33.3%, fibroatheroma 28.9% and TCFA 6.7%. In the distal edge, presence of edge dissection was significantly more frequent when the plaque type at the edge was fibrocalcific (43.8%) or lipid rich (37.5%) than when the plaque was fibrous (10%) p=0.009.nnnCONCLUSIONSnOCT showed higher sensitivity compared to angiography for the identification of edge dissections. A high proportion of patients showed lipid-rich plaques at stent edges. Plaque type at the stent edges has impact on the presence of edge dissections.

Second-generation optical coherence tomography in clinical practice. High-speed data acquisition is highly reproducible in patients undergoing percutaneous coronary intervention

INTRODUCTION AND OBJECTIVESnThe development of second-generation optical coherence tomography (i.e. Fourier domain optical coherence tomography, FD-OCT) has made it possible to perform high speed pullbacks during image acquisition without the need for transient occlusion of the coronary artery. The objective of this study was to assess the reproducibility of FD-OCT systems for characterizing plaque and evaluating stent implantation in patients undergoing a percutaneous coronary intervention.nnnMETHODSnThe study included 45 patients scheduled for percutaneous coronary intervention who were enrolled between May and December 2008. Image acquisition was performed by FD-OCT using a non-occlusive technique and employing pullback speeds ranging from 5 to 20 mm/s. Interstudy, interobserver and intraobserver reproducibility of plaque characterization and stent analysis were assessed.nnnRESULTSnFourier domain imaging was successfully performed in all patients (n=45). The average flush rate was 3+/-0.4 mL/s and the contrast volume per pullback was 16.1+/-3.5 mL. The mean pullback duration and length were 3.2+/-1.2 s and 53.3+/-12.4 mm, respectively. The interstudy reproducibility for visualizing edge dissection, tissue prolapse, intrastent dissection and malapposition was excellent (k=1). The kappa values for interstudy, interobserver and intraobserver agreement on plaque characterization were 0.92, 0.82 and 0.95, respectively.nnnCONCLUSIONSnA second-generation OCT system (i.e. FD-OCT) involving high-speed data acquisition demonstrated good interstudy, interobserver and intraobserver reproducibility for characterizing plaque and evaluating stent implantation in patients undergoing a percutaneous coronary intervention.

Three-dimensional optical frequency domain imaging in conventional percutaneous coronary intervention: the potential for clinical application

Two-dimensional (2D) frequency domain optical coherence tomography (FD-OCT) has enhanced our understanding of coronary atherosclerotic disease and is increasingly being used in conventional percutaneous coronary intervention (PCI) to elucidate mechanisms of disease and improve our understanding of complex coronary anatomy.nnSince the first report of three-dimensional (3D) OCT applied in human coronary vessels,1 the technology has rapidly progressed.2–10 Currently, the main limitation of this technology is the need for off-line creation of 3D reconstructions—prototypes of current generation ‘real time’ (i.e. available peri-procedurally at the ‘push-of-a-button’) remain experimental, work in progress, and are limited by relatively poor image quality/resolution.4 As of now, the potential clinical application of 3D FD-OCT remains undefined.nnRecently, the application of this emerging technology to the coronary bifurcation has allowed visualization and assessment of jailed side branches (SideBs) at a level of detail not previously reported.2–7 The assessment of a jailed SideB, after implantation of a bioresorbable scaffold in the main branch (MainB) of a bifurcation, lead to the proposal of a new classification system based on the assessment of the number of compartments the SideB ostium was divided into, with examples of how this may potentially effect the neointimal response and subsequent coverage of the struts.2nnMore recently, the application of this technology to the coronary bifurcation in patients implanted with conventional metallic stents, utilizing the Terumo optical frequency domain imaging (OFDI) system, was described for the first time.3 Hypotheses related to types of coronary bifurcation (‘parallel’ and ‘perpendicular’ bifurcations) based on the bifurcation angle, and how this leads to certain specific characteristics of the carina, which potentially made the SideB more vulnerable to the effects of carina shift and potential SideB closure, were described. Furthermore, the potential practical application of 3D FD-OCT in guiding the …

New Insights Into the Coronary Artery Bifurcation: Hypothesis-Generating Concepts Utilizing 3-Dimensional Optical Frequency Domain Imaging

Coronary artery bifurcations are a common challenging lesion subset accounting for approximately 10% to 20% of all percutaneous coronary interventions. The provisional T-stenting approach is generally recommended as the first-line management of most lesions. Carina shift is suggested to be the predominant mechanism of side-branch pinching during provisional T-stenting and has been indirectly inferred from bench work and other intravascular imaging modalities. Offline 3-dimensional (3D) reconstructions of patients studied in the first-in-man trial of the high-frequency (160 frames/s) Terumo optical frequency domain imaging system were undertaken using volume-rendering software. Through a series of 3D reconstructions, several novel hypothesis-generating concepts are presented.

Tomografía de coherencia óptica de segunda generación en la práctica clínica. La adquisición de datos de alta velocidad muestra una reproducibilidad excelente en pacientes tratados con intervenciones coronarias percutáneas

Introduccion y objetivos Se ha desarrollado una segunda generacion de sistemas de tomografia de coherencia optica (OCT) (dominio de Fourier, OCT-DF) que permiten las retiradas a alta velocidad sin necesidad de ocluir transitoriamente la arteria coronaria durante la obtencion de imagenes. El objetivo de este estudio es evaluar la reproducibilidad de los sistemas de OCT-DF para la caracterizacion de la placa y la evaluacion de la implantacion del stent en pacientes a los que se practican intervenciones coronarias percutaneas. Metodos Entre mayo y diciembre de 2008, se incluyo en el estudio a 45 pacientes para los que se habia programado una intervencion coronaria percutanea. La adquisicion de la OCT-DF se realizo con una tecnica no oclusiva con velocidades de retirada de entre 5 y 20 mm/s. Se evaluo la reproducibilidad entre estudios, entre observadores y en el observador para la caracterizacion de la placa y el analisis de los stents. Resultados La obtencion de imagenes de dominio de Fourier se realizo satisfactoriamente en todos los pacientes (nxa0=xa045). El ritmo de infusion medio fue de 3xa0±xa00,4 ml/s y el volumen de contraste por retirada, 16,1xa0±xa03,5 ml. La media de duracion y longitud de la retirada fue de 3,2 ± 1,2 s y 53,3xa0±xa012,4 mm. La reproducibilidad entre estudios, en cuanto a la visualizacion de la diseccion del borde, el prolapso tisular, la diseccion en el stent y la mala aposicion, fue excelente (κxa0=xa01). Los valores de kappa para la coincidencia entre estudios, entre observadores y en el observador en la caracterizacion de la placa fueron 0,92, 0,82 y 0,95 respectivamente. Conclusiones La tecnologia de OCT de segunda generacion, que obtiene datos a alta velocidad, muestra buena reproducibilidad entre estudios, entre observadores y en el observador para la caracterizacion de la placa y evaluar la implantacion del stent en pacientes a los que se practican intervenciones coronarias percutaneas.