1. Articles from Paul G. Yock

    1-6 of 6
    1. Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography

      Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography

      Background In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high-definition intravascular ultrasound (HD-IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD-IVUS compared with 40 MHz IVUS with respect to polymeric-strut visualization, quantitative and qualitative analysis, and feasibility of high-speed pullback in the assessment of BRS. Methods and Results In a bench-test model, 361 struts were analyzed to evaluate the influence of ultrasound-beam angles and proximity of adjacent struts on IVUS visualization of BRS struts. Various settings ...

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    2. Acute stent recoil and optimal balloon inflation strategy: an experimental study using real-time optical coherence tomography

      Acute stent recoil and optimal balloon inflation strategy: an experimental study using real-time optical coherence tomography

      Aims: Our aim was to evaluate stent expansion and acute recoil at deployment and post-dilatation, and the impact of post-dilatation strategies on final stent dimensions. Methods and results: Optical coherence tomography (OCT) was performed on eight bare metal platforms of drug-eluting stents (3.0 mm diameter, n=6 for each) during and after balloon inflation in a silicone mock vessel. After nominal-pressure deployment, a single long (30 sec) vs. multiple short (10 sec x3) post-dilatations were performed using a non-compliant balloon (3.25 mm, 20 atm). Stent areas during deployment with original delivery systems were smaller in stainless steel stents ...

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    3. Quantitative precision of optical frequency domain imaging: direct comparison with frequency domain optical coherence tomography and intravascular ultrasound

      Quantitative precision of optical frequency domain imaging: direct comparison with frequency domain optical coherence tomography and intravascular ultrasound

      No systematic validation study is available with optical frequency domain imaging (OFDI), directly compared with frequency domain optical coherence tomography (FD-OCT) and intravascular ultrasound (IVUS). Controversy also remains about the impact of different stent contour tracing methods by OFDI/FD-OCT. In vitro: coronary phantom models (1.51–5.04 mm) were imaged with OFDI, FD-OCT, and IVUS, demonstrating excellent quantitative precision with a slight overestimation of mean lumen diameter (difference 0.01–0.02 mm). In vivo: corresponding 64 OFDI/IVUS images of stented coronary segments from 20 swines were analyzed. Minimum lumen area by OFDI was larger than IVUS ...

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    4. Evaluation of the Peri-strut Low Intensity Area Following Sirolimus- and Paclitaxel-Eluting Stents Implantation: Insights From an Optical Coherence Tomography Study in Humans

      Evaluation of the Peri-strut Low Intensity Area Following Sirolimus- and Paclitaxel-Eluting Stents Implantation: Insights From an Optical Coherence Tomography Study in Humans
      Background: In previous pathological studies, paclitaxel-eluting stents (PES) showed greater fibrin deposition around stent struts, while sirolimus-eluting stent (SES) showed predominance of inflammatory cells with less fibrin deposition than PES. However, there are limited in-vivo data clarifying those qualitative differences in the process of vascular healing after 1st-generation drug-eluting stents (DES) implantation. A recent animal study has shown that peri-strut low intensity area (PLIA) seen in optical coherence tomography (OCT) imaging might represent the process of hyaluronic acid and proteoglycan replacing fibrin. Methods: A total of 60 patients who underwent 6-month follow-up OCT after SES (n=34) and PES (n ...
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    5. In Vivo Comparison Between Optical Coherence Tomography and Intravascular Ultrasound for Detecting Small Degrees of In-Stent Neointima After Stent Implantation

      Objectives: The purpose of this study was to evaluate optical coherence tomography (OCT) for detecting small degrees of in-stent neointima (ISN) after stent implantation compared with intravascular ultrasound (IVUS). Background: The importance of detecting neointimal coverage of stent struts has grown with the appreciation of the increased risk for late stent thrombosis after drug-eluting stent (DES) implantation. Intravascular ultrasound, the current standard for evaluating the status of DES, lacks the resolution to detect the initial neointimal coverage. Optical coherence tomography has greater resolution but has not yet been compared with IVUS in vivo with histological correlation for validation. Methods: Intravascular ...
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    6. Local Determinants and Clinical Significance of Thrombus Formation Following Sirolimus-Eluting Stent Implantation: Insights from Optical Coherence Tomography Analysis

      Angioscopic analyses have shown the presence of subclinical thrombus in sirolimus-eluting stents (SES) is more common than the clinical incidence of stent thrombosis. However, the determinants and long term significance of subclinical thrombus remain unknown. Thirty five patients (44 stents) who received SES underwent 6 months follow-up optical coherence tomography (OCT). Patients were divided into 2 groups according to the presence of thrombus by OCT. Cross-sectional images were analyzed every 1mm. Stent eccentricity index (SEI; minimum stent diameter divided by maximum stent diameter) was determined in each cross section (CS). To assess the unevenness of neointimal thickness (NIT), a neointimal ...
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    1-6 of 6
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    1. (5 articles) Stanford University
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    Evaluation of the Peri-strut Low Intensity Area Following Sirolimus- and Paclitaxel-Eluting Stents Implantation: Insights From an Optical Coherence Tomography Study in Humans Quantitative precision of optical frequency domain imaging: direct comparison with frequency domain optical coherence tomography and intravascular ultrasound Acute stent recoil and optimal balloon inflation strategy: an experimental study using real-time optical coherence tomography Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography Optical coherence tomography findings in conversion disorder: are there any differences in the etiopathogenesis of subtypes? Mid-infrared Fourier-domain optical coherence tomography with a pyroelectric linear array On-chip polarization beam splitter design for optical coherence tomography Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples Direct comparison of optical coherence tomography and high-definition 60-MHz intravascular ultrasound imaging of intra-procedural stent thrombosis in a patient with acute coronary syndrome Determining Optic Nerve Cupping Using Optical Coherence Tomography (OCT) versus a New Electronic Mobile Device Use of optical coherence tomography to detect retinal nerve fiber loss in children with optic pathway glioma Diagnostic Performance of Macular Versus Peripapillary Vessel Parameters by Optical Coherence Tomography Angiography for Glaucoma