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Intracoronary Imaging
摘要： Coronary angiography represents both the gold standard for diagnosis of coronary artery disease and the main guidance for percutaneous coronary intervention (PCI). Yet, coronary angiography is well known to not be optimal in appreciating the whole spectrum of lesions that may cause clinical problems in patients with coronary artery disease. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) represent the 2 contemporary invasive intracoronary imaging modalities aimed at improving the detection of coronary details. Their potential is extraordinary but their use for improving coronary disease diagnosis is not standardized. Moving from diagnosis to treatment, PCI based on drug-eluting stent (DES) implantation often requires a series of manipulations with different techniques and devices. Last generation DES types have similar technical features and share a comparable ability to scaffold coronary lesions. Not surprisingly, lesion complexity is known to be associated with increased procedure challenges that may be tackled by different strategies. The selection of devices and the assessment of appropriate DES implantation may be based on either angiography or intracoronary imaging techniques like IVUS or OCT. Both techniques have evolved over time and offer the possibility to see details of coronary lesions and stent/vessel interactions that are impossible to be captured and measured by angiography. So far, thousands of studies with different designs have been performed, but they have not been able to make interventional cardiologists act in a homogeneous way. Consequently, intravascular imaging is selected on the basis of individual yield, with an impressive variability across different countries and operators. Reimbursement issues are part of the game but do not entirely explain the overall underutilization of intravascular imaging (especially in Western countries where a lot of expensive devices are routinely incorporated in interventional practice). In reality, the application of intracoronary imaging adds complexity to PCI, requires adequate technical skills, and by itself does not necessarily improve the clinical outcome. As compared with angiography guidance, IVUS and OCT are able to provide (in real time) many more coronary details. Such angiographically invisible details need to be recognized by the operator to properly react to improve the clinical outcome of treated patients. Because of the impressive amount of details and possible measures/cutoffs, the identification of both impactful features (deserving attention) and best reactions (additional technical steps with corrective efficacy) is pivotal. Yet, data collected by IVUS studies have not been concordant and this has resulted in overall limited clinical penetration: many catheterization laboratories are actually working without any access to intracoronary imaging. Furthermore, although rare, imaging catheter-related complications may occur so that a safety issue has to be considered any time the expected benefit is not well established in clinical practice. On the bases of these concepts, it is evident that the intracoronary imaging clinical impact may come from the correct identification and appropriate processing of those details that may help (1) to improve the PCI strategy (technique/device selection, that is, PCI planning) and (2) to facilitate the achievement of improved stenting result (ie, PCI optimization). As shown in the Figure, among all the information captured by intracoronary imaging, a limited series of imaging-based pre-PCI findings can be easily incorporated in the PCI planning (lesion preparation and stent selection). Similarly, some key intra-PCI findings (stent underexpansion, stent edge dissections, and strut malapposition) can be searched in order to optimize the stent implantation result. The feasibility of this approach is supported by the daily experience of many high volume centers. Yet, the overall clinical impact of image guidance in PCI is still unrecognized, and large studies in the field are needed. Recently-collected data started shedding new light on both IVUS and OCT. The large study by Maehara et al, although not randomized, allowed to run a propensity-matched comparison between thousands of IVUS-guided and angiography-guided procedures. IVUS use was associated with different procedure conduction and reduced major adverse events incidence at up to 2 years. Of note, the clinical benefit comprised significant improvements of hard end points, namely stent thrombosis, myocardial infarction, and cardiac mortality. Such results fit well with the recent ULTIMATE prospective randomized trial (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in 'All-Comers' Coronary Lesions). The ULTIMATE investigators randomized 1448 all-comer patients who required DES implantation to either IVUS guidance or angiography guidance. As compared with angiography, randomization to IVUS guidance was associated with different procedure course (higher contrast administration, larger and longer stents, and higher inflation pressures) and warranted lower target vessel failures with IVUS at 12 months. OCT, as compared with IVUS, represents a younger technique, but data are growingly been collected because it has the appeal of offering higher resolution. The specific image generation process of OCT translates into the need of dedicated experience but has the potential for shorter learning curve. The possible clinical impact of OCT use in PCI guidance has been started to be highlighted by the results of the CLI-OPCI II study (Centro per la Lotta Contro l'Infarto-Optimisation of Percutaneous Coronary Intervention II). In this large registry, specific definitions for OCT features of suboptimal stent results were found to be independently associated with adverse clinical outcome after PCI. For sure, more complex PCIs (where the risk of stent thrombosis and restenosis is higher), are expected to benefit more from PCI refinements. Thus, two large prospectively randomized trials (OCTOBER, and ILUMIEN IV, and URL: https://www.clinicaltrials.gov. Unique identifier: NCT03507777) comparing OCT and angiographic guidance are actually ongoing and have been powered to explore the benefit of OCT guidance (using rigorous OCT-based PCI optimization algorithms) in, respectively, bifurcated lesions and complex patients. In conclusion, intravascular imaging modalities are entering a new era because the recently collected data seem to show new thresholds and targets for PCI planning and optimization. Thus, IVUS and OCT are going to become the ideal glasses that interventional cardiologists should wear anytime something looks unclear before, during or after PCI. Appropriate education, standardization of operative protocols and definitions of best clinical settings for application represent the future challenges for the intravascular imaging clinical implementation.
关键词： intravascular ultrasound,angiography,myocardial infarction,Editorials,diagnosis,optical coherence tomography,coronary artery disease,percutaneous coronary intervention
更新于2025-09-23 15:22:29
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Macrophage uptake switches on OCT contrast of superparamagnetic nanoparticles for imaging of atherosclerotic plaques
摘要： Background: Optical coherence tomography (OCT) is an intravascular, high-resolution imaging technique that is used to characterize atherosclerotic plaques. However, the identification of macrophages as important markers of inflammation and plaque vulnerability remains difficult. Here, we investigate whether the uptake of very small iron oxide particles (VSOP) in macrophages, that cluster in phagolysosomes and allow high-quality magnetic resonance imaging (MRI) of atherosclerotic plaques, and uptake of ferumoxytol nanoparticles enhance detection of macrophages by OCT. Materials and methods: RAW 264.7 macrophage cells were incubated with VSOP (1 and 2 mM Fe) that have been clinically tested and ferumoxytol (8.9 mM Fe) that is approved for iron deficiency treatment and currently investigated as an MRI contrast agent. The light scattering of control macrophages, nanoparticle-labeled macrophages (2,000,000 in 500 μL) and nanoparticle suspensions was measured in synchronous wavelength scan mode using a fluorescence spectrophotometer. For OCT analyses, pellets of 8,000,000 non-labeled, VSOP-labeled and ferumoxytol-labeled RAW 264.7 macrophages were imaged and analyzed on an OPTIS? OCT imaging system. Results: Incubation with 1 and 2 mM VSOP resulted in uptake of 7.1±1.5 and 12±1.5 pg Fe per cell, which increased the backscattering of the macrophages in spectrophotometry 2.5- and 3.6-fold, whereas incubation with 8.9 mM Fe ferumoxytol resulted in uptake of 6.6±2 pg Fe per cell, which increased the backscattering 1.5-fold at 700 nm. In contrast, backscattering of non-clustered nanoparticles in suspension was negligible. Accordingly, OCT imaging could visualize significantly increased backscattering and signal attenuation of nanoparticle-labeled macrophages in comparison with controls. Conclusion: We conclude that VSOP and, to a lesser extent, ferumoxytol increase light scattering and attenuation when taken up by macrophages and can serve as a multimodal imaging probe for MRI and OCT to improve macrophage detection in atherosclerotic plaques by OCT in the future.
关键词： intravascular,magnetic resonance imaging,multimodal imaging,optical coherence tomography,vulnerability,inflammation
更新于2025-09-23 15:22:29
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Intravascular Photothermal Strain Imaging for Lipid Detection
摘要： Cardiovascular disease (CVD) is one of the major threats to humanity, accounting for one-third of the world’s deaths. For patients with high-risk CVD, plaque rupture can lead to critical condition. It is therefore important to determine the stability of the plaque and classify the patient’s risk level. Lipid content is an important determinant of plaque stability. However, conventional intravascular imaging methods have limitations in ?nding lipids. Therefore, new intravascular imaging techniques for plaque risk assessment are urgently needed. In this study, a novel photothermal strain imaging (pTSI) was applied to an intravascular imaging system for detecting lipids in plaques. As a combination of thermal strain imaging and laser-induced heating, pTSI differentiates lipids from other tissues based on changes in ultrasound (US) velocity with temperature change. We designed an optical pathway to an intravascular ultrasound catheter to deliver 1210-nm laser and US simultaneously. To establish the feasibility of the intravascular pTSI system, we experimented with a tissue-mimicking phantom made of fat and gelatin. Due to the difference in the strain during laser heating, we can clearly distinguish fat and gelatin in the phantom. The result demonstrates that pTSI could be used with conventional intravascular imaging methods to detect the plaque lipid.
关键词： photothermal strain imaging,intravascular ultrasound (IVUS),thermal strain imaging,lipid detection,unstable plaque,intravascular imaging,cardiovascular disease
更新于2025-09-23 15:21:01
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Novel predictor of target vessel revascularization after coronary stent implantation: Intraluminal intensity of blood speckle on intravascular ultrasound
摘要： Background: The difference in intraluminal intensity of blood speckle (IBS) on integrated backscatter-intravascular ultrasound (IB-IVUS) across the coronary artery stenosis (i.e., ΔIBS) has been reported to negatively correlate with fractional flow reserve. Fractional flow reserve after coronary stenting is known as a predictor of target vessel revascularization (TVR). However, the relation between ΔIBS and TVR is unclear. Methods: Seven hundred and three vessels which underwent percutaneous coronary intervention with stents were screened. Vessels without IVUS-guidance and follow-up information were excluded. Intraluminal IBS values were measured using IB-IVUS in cross-sections at the ostium of the target vessel and at the distal reference of implanted stent. ΔIBS was calculated as (distal IBS) ? (ostium IBS). Results: A total of 393 vessels were included. Mean ΔIBS at postprocedure was 6.22 (cid:1) 5.65. During the follow-up period (11.2 (cid:1) 3.1 months), 24 cases (6.1%) had TVR. ΔIBS was significantly greater in the vessels with TVR than in those without (11.10 (cid:1) 5.93 vs. 5.90 (cid:1) 5.49, P <0.001). In receiver operating characteristic curve analysis, ΔIBS significantly predicted TVR (AUC 0.74, best cut-off value 8.24, P < 0.001). Multiple logistic regression analysis showed use of drug eluting stent and ΔIBS ≥ 8.24 as independent predictors of TVR. Conclusions: ΔIBS at postprocedure was significantly associated with TVR. IVUS may be able to predict TVR by physiological assessment with measurement of ΔIBS.
关键词： intravascular ultrasound,percutaneous coronary intervention,target vessel revascularization
更新于2025-09-23 15:21:01
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A novel intensity-based multi-level classification approach for coronary plaque characterization in intravascular ultrasound images
摘要： Background: Intravascular ultrasound (IVUS) is a commonly used diagnostic imaging method for coronary artery disease. Virtual histology (VH) characterizes the plaque components into fibrous tissue (FT), fibro-fatty tissue (FFT), necrotic core (NC), or dense calcium (DC). However, VH can obtain only a single-frame image in one cardiac cycle, and specific software is needed to obtain the radio frequency data. This study proposed a novel intensity-based multi-level classification model for plaque characterization. Methods: The plaque-containing regions between the intima and the media-adventitia were segmented manually for all IVUS frames. A total of 54 features including first order statistics, grey level co-occurrence matrix, Law’s energy measures, extended grey level run length matrix, intensity, and local binary pattern were estimated from the plaque-containing regions. After feature extraction, optimal features were selected using principle component analysis (PCA), and these were utilized as the input for the classification models. Plaque components were classified into FT, FFT, NC, or DC using an intensity-based multi-level classification model consisting of three different nets. Net 1 differentiated low-intensity components into FT/FFT and NC/DC groups. Then, net 2 subsequently divided FT/FFT into FT or FFT, whereas the remainder and high-intensity components were classified into NC or DC via net 3. To improve classification accuracy, each net utilized three different input features obtained by PCA. Classification performance was evaluated in terms of sensitivity, specificity, accuracy, and receiver operating characteristic curve. Results: Quantitative results indicated that the proposed method showed significantly high classification accuracy for all tissue types. The classifiers had classification accuracies of 85.1%, 71.9%, and 77.2%, respectively, and the areas under the curve were 0.845, 0.704, and 0.783. In particular, the proposed method achieved relatively high sensitivity (82.0%) and specificity (87.1%) for differentiating between the FT/FFT and NC/DC groups. Conclusions: These results confirmed the clinical applicability of the proposed approach for IVUS-based tissue characterization.
关键词： Intravascular ultrasound,Intensity-based multi-level classification,Texture features,Plaque characterization,Principle component analysis
更新于2025-09-11 14:15:04
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First-in-Human Images of Coronary Atherosclerosis and Coronary Stents Using a Novel Hybrid Intravascular Ultrasound and Optical Coherence Tomographic Catheter
摘要： We report the first-in-human images with any hybrid imaging catheter combining intravascular ultrasound (IVUS) and optical coherence tomography (OCT). The catheter has a 2.8-F imaging window with a 40-MHz center frequency for IVUS imaging. The IVUS and OCT beams are aligned with each other, allowing inherent coregistration and immediate simultaneous image review. Imaging was performed in a 74-year-old male patient with a recent inferior ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention in the distal right coronary artery. Imaging was performed over 90 mm of the right coronary artery at a pull-back speed of 25 mm/s, with contrast flushing at 3 ml/s for 5 s. Figure 1 highlights the complementary roles of IVUS and OCT to characterize atherosclerotic plaque types. A nonculprit lesion was present in the mid left anterior descending coronary artery. Staged intervention was performed with implantation of a Promus 2.75 × 20 mm (Boston Scientific, Natick, Massachusetts) stent. Imaging was performed after stent implantation over a 70-mm length at a pull-back speed of 25 mm/s and contrast flush at 4 ml/s for 4 s. Imaging findings in the left anterior descending coronary artery and D1 are shown in Figure 2. The imaging pull-back shows a dissection distal to the left anterior descending coronary artery stent. Near-field findings of dissection and stent apposition are better appreciated on OCT, while deeper features such as side branches and plaque burden are better assessed on IVUS. This first in vivo experience of hybrid IVUS and OCT demonstrates the synergistic ability of these modalities to characterize coronary atherosclerosis and coronary interventions.
关键词： optical coherence tomography,intravascular imaging,intravascular ultrasound
更新于2025-09-10 09:29:36
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Comparative Quantification of Arterial Lipid by Intravascular Photoacoustic-Ultrasound Imaging and Near-Infrared Spectroscopy-Intravascular Ultrasound
摘要： Intravascular photoacoustic-ultrasound (IVPA-US) imaging and near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) are two hybrid modalities that detect arterial lipid, with comparison necessary to understand the relative advantages of each. We performed in vivo and ex vivo IVPA-US imaging of the iliac arteries of Ossabaw swine with metabolic syndrome (MetS) and lean swine to investigate sensitivity for early-stage atherosclerosis. We repeated imaging ex vivo with NIRS-IVUS for comparison to IVPA-US and histology. Both modalities showed significantly greater lipid in MetS vs. lean swine, but only IVPA-US localized the lipid as perivascular. To investigate late-stage atherosclerosis, we performed ex vivo IVPA-US imaging of a human coronary artery with comparison to NIRS-IVUS and histology. Two advanced fibroatheromas were identified, with agreement between IVPA-measured lipid area and NIRS-derived lipid content. As confirmed histologically, IVPA-US has sensitivity to detect lipid content similar to NIRS-IVUS and provides additional depth resolution, enabling quantification and localization of lipid cores within plaques.
关键词： Swine,Lipid core plaque,Near-infrared spectroscopy,Human,Intravascular imaging,Photoacoustic imaging,Atherosclerosis,Perivascular adipose tissue
更新于2025-09-10 09:29:36
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Corner Detection Based Automatic Segmentation of Bioresorbable Vascular Scaffold Struts in IVOCT Images
摘要： Bioresorbable Vascular scaffold (BVS) is a promising type of stent in percutaneous coronary intervention. Struts apposition assessment is important to ensure the safety of implanted BVS. Currently, BVS struts apposition analysis in IVOCT images still depends on manual delineation of struts, which is labor intensive and time consuming. Automatic struts segmentation is highly desired to simplify and speed up quantitative analysis. However, it is difficult to segment struts accurately based on the contour, due to the influence of fractures inside strut and blood artifacts around strut. In this paper, a novel framework of automatic struts segmentation based on four corners is introduced, in which priori knowledge is utilized that struts have obvious feature of box-shape. Firstly, a cascaded AdaBoost classifier based on enriched haar-like features is trained to detect struts corners. Then, segmentation result can be obtained based on the four detected corners of each strut. Tested on five pullbacks consisting of 483 images with strut, our novel method achieved an average Dice’s coefficient of 0.82 for strut segmentation areas. It concludes that our method can segment struts accurately and robustly. Furthermore, automatic struts malapposition analysis in clinical practice is feasible based on the segmentation results.
关键词： Intravascular Optical Coherence Tomography (IVOCT),Bioresorbable Vascular Scaffold (BVS),Struts Segmentation,Corner Detection,AdaBoost Classifier
更新于2025-09-10 09:29:36
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[Lecture Notes in Computer Science] Intravascular Imaging and Computer Assisted Stenting and Large-Scale Annotation of Biomedical Data and Expert Label Synthesis Volume 11043 (7th Joint International Workshop, CVII-STENT 2018 and Third International Workshop, LABELS 2018, Held in Conjunction with MICCAI 2018, Granada, Spain, September 16, 2018, Proceedings) || Deep Learning-Based Detection and Segmentation for BVS Struts in IVOCT Images
摘要： Bioresorbable Vascular Sca?old (BVS) is the latest stent type for the treatment of coronary artery disease. A major challenge of BVS is that once it is malapposed during implantation, it may potentially increase the risks of late stent thrombosis. Therefore it is important to analyze struts malapposition during implantation. This paper presents an automatic method for BVS malapposition analysis in intravascular optical coherence tomography images. Struts are ?rstly detected by a detector trained through deep learning. Then, struts boundaries are segmented using dynamic programming. Based on the segmentation, apposed and malapposed struts are discriminated automatically. Experimental results show that the proposed method successfully detected 97.7% of 4029 BVS struts with 2.41% false positives. The average Dice coe?cient between the segmented struts and ground truth was 0.809. It concludes that the proposed method is accurate and e?cient for BVS struts detection and segmentation, and enables automatic malapposition analysis.
关键词： Bioresorbable vascular sca?old,Deep learning,Intravascular optical coherence tomography,Detection and segmentation
更新于2025-09-04 15:30:14