Optical Coherence Tomography Pullbacks Research Articles

Cardiac allograft vasculopathy in heart transplanted recipients: The multivessel study

BackgroundCardiac Allograft Vasculopathy (CAV) is a prevailing complication following heart transplantation. We aimed to investigate if CAV causes equal vascular remodeling in the major coronary arteries using quantitative Optical Coherence Tomography (OCT) and to explore the prognostic potential of OCT derived measurements from each coronary artery. Methods64 heart transplanted patients had a combined total of 114 full three-vessel OCTs and coronary angiographies performed between 2013 and 2019. OCT pullbacks were categorized by angiographic CAV classification. Registration of disease progression was censored on July 1, 2022. ResultsOCT recordings were classified as follows: No significant CAV, n = 73; mild CAV, n = 18; moderate CAV, n = 13 and severe CAV, n = 10. From inter-coronary comparison of severe CAV, we found significant differences by both average lumen/intima ratio (p<0.0001) and average intima/media ratio (p<0.0001). The left descending artery (LAD) showed increasingly smaller luminal areas and larger intimal areas within CAV groups compared with the remaining coronary arteries. No differences were seen between major coronary arteries without significant CAV.LAD derived average intima/media ratio (HR: 3.39; 95% CI: 1.33 to 8.63; p = 0.01) and average lumen/intima ratio (HR: 2.77; 95% CI: 1.09 to 7.05; p = 0.03) were the strongest predictors of CAV progression. LAD predictions were superior to predictions based on all three coronary arteries. ConclusionsLAD derived OCT measurements were increasingly affected by CAV compared with the circumflex and right coronary artery. Average lumen/intima and intima/media ratios were the strongest predictors of CAV progression.

Deep-learning based analysis of intracoronary optical coherence tomography images: detection and characterization of lipid plaques

Abstract Background Intracoronary optical coherence tomography (OCT) enables in vivo detection and characterization of atherosclerotic disease. However, manual assessment of OCT images is time-consuming and subject to intra- and interobserver variability. Therefore, automated and trustworthy methods for plaque assessment are warranted. Purpose To develop and validate an artificial intelligence based algorithm for detection and characterization of lipid plaques on OCT images. Methods From the prospective, observational PECTUS-obs study, we studied a representative subset of OCT pullbacks performed in fractional flow reserve-negative non-culprit lesions in patients presenting with myocardial infarction. Manual segmentation of cross-sectional frames (e.g. lumen, tunica intima including the fibrous cap, tunica media and lipid pools) was performed by trained experts. Pullbacks were randomly divided into a training and test set. For automated segmentation and analysis, a two-dimensional no-new U-shaped neural network (nnUNet) was constructed with 5-fold cross validation. To test the diagnostic performance of the nnUnet for detection of lipid plaques, sensitivity, specificity and Cohen’s kappa were calculated. As for plaque characterization, the lipid arc and minimal fibrous cap thickness were measured manually in the test set on each frame containing a lipid plaque. Values of lipid arc and minimal fibrous cap thickness obtained following automated assessment were compared to manual analysis using the intraclass correlation coefficient (ICC) for absolute agreement. Results In total, 1215 frames were used for training and 162 frames for testing of the nnUNet. Lipid plaques were present in 77 frames (47.5%) in the test set. Substantial agreement (κ=0.79) for detection of a lipid plaque was achieved with a sensitivity and specificity of 96.1% and 83.5%, respectively. As for plaque characterization, we found good reliability for lipid arc assessment (ICC 0.88, mean difference 6±32º) and moderate reliability for assessment of the minimal fibrous cap thickness (ICC 0.54, mean difference 23±140µm). Conclusion We developed a deep learning algorithm for automated analysis of intracoronary OCT images, that was able to accurately detect lipid plaques. Moreover, the algorithm showed promising results in terms of plaque characterization. With further refinements, the developed algorithm has the potential to reduce the time required for OCT interpretation, ultimately enabling more efficient, real-time use of this imaging modality in clinical practice.

Comprehensive appraisal of cardiac motion artefact in optical coherence tomography.

The relation between cardiac motion artefact (CMA) in optical coherence tomography (OCT) and the phases of cardiac cycle is unclear. Optical coherence tomography pullbacks containing metallic stents were co-registered with angiography and retrospectively analyzed. The beginning of three phases, namely ejection, rapid-inflow and diastasis, was identified in angiography. Rotation, shortening, elongation and repetition were qualitatively labelled as CMA artefacts. Platforms with coaxial longitudinal connectors (ML8 and Magmaris) entered a quantitative sub-study, consisting of measuring the length of their connector at the beginning of each phase. A total of 261 stents (127 patients) were analyzed, including 105 stents for quantitative sub-study. CMA was detected in 61 (23.4%) stents: rotation in 6 (2.3%), shortening in 50 (19.2%), elongation in 51 (19.5%) and repetition in 12 (4.6%). Shortening was always observed during ejection phase, while elongation and repetition were always observed during rapid-inflow. Rotation occurred in both ejection and rapid-inflow phases, while no artefact was reported during diastasis. Longitudinal connectors measured in early ejection phase and in early rapid-inflow phase were shorter and longer, respectively, than those measured in diastasis, irrespective of the presence of CMA in the qualitative assessment. Cardiac motion artefact is prevalent in OCT studies, but shortening and elongation of vascular structures occur during early ejection and during early rapid-inflow, respectively, to a greater or lesser extent in all cases. Diastasis is free of CMA and hence the period in which longitudinal measurements can be more accurately quantified.

Feasibility and safety of non-contrast optical coherence tomography imaging using hydroxyethyl starch in coronary arteries

Intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition. Alternative flushing media needs to be investigated to reduce the risk of contrast-induced renal dysfunction. We investigated the feasibility and safety of pentastarch (hydroxyethyl starch) for clinical OCT imaging. We prospectively enrolled 43 patients with 70 coronary lesions (46-stented; 24-native). Total 81 OCT pullback pairs were obtained by manual injection of iodine contrast, followed by pentastarch. Each pullback was assessed frame-by-frame using an automated customized lumen contour/stent strut segmentation algorithm. Paired images were compared for the clear image segments (CIS), blood-flushing capability, and quantitative morphometric measurements. Overall image quality, as assessed by the proportion of CIS, was comparable between the contrast- and pentastarch-flushed images (97.1% vs. 96.5%; p = 0.160). The pixel-based blood-flushing capability was similar between the groups (0.951 [0.947–0.953] vs. 0.950 [0.948–0.952], p = 0.125). Quantitative two- and three-dimensional morphometric measurements of the paired images correlated well (p < 0.001) with excellent inter-measurement variability. All patients safely underwent OCT imaging using pentastarch without resulting in clinically relevant complications or renal deterioration. Non-contrast OCT imaging using pentastarch is clinically safe and technically feasible with excellent image quality and could be a promising alternative strategy for patients at high risk of renal impairment.

Comparison between different approaches to evaluate fibrous cap thickness in sequential optical coherence tomography studies.

In this in-vivo human study we tested the reproducibility for optical coherence tomography (OCT) assessment of lumen area (LA) and plaque components measurements, such as lipid arc extension and fibrous cap thickness (FCt). We tested the variability of LA, lipid arc and FCt assessments in two repeated OCT pullbacks from the same diseased coronary segment matched using fiduciary anatomical landmarks. In particular, for the reliability of minimal FCt measurement we compared four different approaches based on continuous (longitudinal) or segmental (spot) individuation of smaller thickness: 1) comparison of single minimal FCt individuated alongside all plaque extension in the two pullbacks (Longitudinal (L)-spot minimal FCt value); 2) comparison of the mean FCt values of the plaque in the two pullbacks (L-plot mean FCt value); 3) comparison between the single minimal FCt value obtained in the first pullback and the single FCt obtained in the matched CS of second pullback (L-spot CS matched FCt value); 4) comparison of measurements obtained by visual selection of CS with minimal FCt s in the two pullbacks (single-spot minimal FCt value). From the paired analyses of 20 non culprit lesions (accounting for a total of 387 matched CS), we found a suboptimal in-segment correlation for LA (Intra-Class Coefficient [ICC] 0.731), but a good in-segment correlation for lipid arc (ICC 0.963). Regarding FCt measurement, a high reproducibility was obtained applying continuous assessment; in particular, the best correlation was observed with L-spot minimal FCt value and the L-plot mean FCt (ICC 0.893 and 0.952, respectively) with small inter-pullback differences (confidence intervals less than 0.04 mm). In this methodological study we observed a good reproducibility for quantitative plaque measurements with OCT confirming its reliability for serial assessment. In particular, longitudinal measurement in multiple adjacent frames seems to be the more accurate and reproducible approach for sequential FCt assessment.

A Deep Learning Method for Motion Artifact Correction in Intravascular Photoacoustic Image Sequence.

In vivo application of intravascular photoacoustic (IVPA) imaging for coronary arteries is hampered by motion artifacts associated with the cardiac cycle. Gating is a common strategy to mitigate motion artifacts. However, a large amount of diagnostically valuable information might be lost due to one frame per cycle. In this work, we present a deep learning-based method for directly correcting motion artifacts in non-gated IVPA pullback sequences. The raw signal frames are classified into dynamic and static frames by clustering. Then, a neural network named Motion Artifact Correction (MAC)-Net is designed to correct motion in dynamic frames. Given the lack of the ground truth information on the underlying dynamics of coronary arteries, we trained and tested the network using a computer-generated dataset. Based on the results, it has been observed that the trained network can directly correct motion in successive frames while preserving the original structures without discarding any frames. The improvement in the visual effect of the longitudinal view has been demonstrated based on quantitative evaluation of the inter-frame dissimilarity. The comparison results validated the motion-suppression ability of our method comparable to gating and image registration-based non-learning methods, while maintaining the integrity of the pullbacks without image preprocessing. Experimental results from in vivo intravascular ultrasound and optical coherence tomography pullbacks validated the feasibility of our method in the in vivo intracoronary imaging scenario.

Abstract 14241: Feasibility and Safety of Non-Contrast Optical Coherence Tomography Imaging Using Hydroxyethyl Starch in Coronary Arteries

Background/Objectives: Contemporary high-resolution intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition. There is a growing need for an alternative flushing media other than iodine contrast to reduce the risk of acute kidney injury. To address this issue, we investigated the safety and feasibility of hydroxyethyl starch (pentastarch) as a flushing media for OCT image acquisition and compared with the contrast media flushed images. Methods: We prospectively enrolled 43 patients with 70 coronary lesions (46 stented and 24 pre-stented or non-culprit lesions). Paired OCT images were obtained by manual injection of iodine contrast (average 12 mL), followed by pentastarch (average 15 mL). A total of 162 runs (81 pairs) were analyzed and each OCT pullback was assessed on a frame-by-frame basis by automated customized lumen contour and stent strut segmentation algorithm. Results: Image quality as assessed by proportion of clear image segments were comparable between the contrast media and pentastarch flushed images (93.3% vs. 93.7%; p=0.501). Pixel-based flushing capability showed no significant difference between the paired image segments (median(IQR), 0.951(0.947-0.953) vs. 0.951(0.949-0.952), p=0.264; Figure). Quantitative measurements of minimal stent area (R 2 =0.977, p&lt;0.001), minimal lumen area (R 2 =0.983, p&lt;0.001) correlated well between the paired OCT runs. There were no clinically relevant complications associated with OCT imaging with pentastarch such as anaphylaxis, life-threatening arrhythmia, or acute renal deterioration. Conclusions: Intracoronary OCT using pentastarch is safe and technically feasible without affecting the optical signal intensity and overall image quality. Non-contrast imaging with pentastarch significantly reduces the obligatory iodine contrast load, therefore, could be considered as a promising strategy in high-risk patients for renal impairment.

OCT sequence registration before and after percutaneous coronary intervention (stent implantation)

To assess the progression of coronary artery disease, Optical Coherence Tomography (OCT) pullbacks acquired at different timepoints should be compared. However, the assessment of temporal sequences is a difficult task, as motion artifacts in the longitudinal and axial plane can decrease the quality of the manual inspection. To address this challenge, the current study presents a two-stage computational framework for the longitudinal and axial registration of two OCT pullbacks. During the first stage of the process, we focus on the accurate detection of the matching image pairs from the respective series, while during the second stage we focus on the axial registration of the matched pairs so that their common features are aligned. The dataset used includes 19 patients from two clinical centers, with two OCT pullbacks per patient: one before the stent implantation procedure and one after it. We applied our method on a synthetic dataset of OCT pullbacks, which was generated based on the in-vivo OCT pullbacks to reproduce the motion artifacts across the planes. In addition, the proposed method was validated on the 19 pairs of in-vivo OCT pullbacks with annotated pre/post stent deployment data. The method was able to reduce the alignment error from 32.17±26.14 to 5.6±6.6 frames, the rotational error from 11.59°±11.22° to 1.18°±0.81° and the distance error from 3.07mm±1.52mm to 0.46mm±0.44mm. In addition, the mean Mutual Information similarity increased by 13.47% after the longitudinal registration and an additional 123.33% after the axial registration on top of the previous one.

Automatic assessment of calcified plaque and nodule by optical coherence tomography adopting deep learning model.

Optical coherence tomography (OCT) has become the best imaging tool to assess calcified plaque and nodule. However, every OCT pullback has numerous images, and artificial analysis requires too much time and energy. Thus, it is unsuitable for clinical application. This study aimed to develop and validate an automatic assessment of calcified plaque and nodule by OCT using deep-learning model. The OCT images of calcified plaque and nodule were labeled by two expert readers based on the consensus. A deep-learning model with a MultiScale and MultiTask u-net network (MS-MT u-net) was developed. Then, with the ground truth labeled by expert readers as reference, the diagnostic accuracy and agreement of the model was validated. For the pixelwise evaluation of calcified plaque, the model had a high performance with precision (93.95%), recall (88.95%), and F1 score (91.38%). For the lesion-level evaluation of calcified plaque, the quantitative metrics by the model excellently correlated with the ground truth (calcium score, r = 0.90, p < 0.01; calcified volume, r = 0.99, p < 0.01). For calcified nodules, the model showed excellent diagnostic performance including sensitivity (91.7%), specificity (89.3%), and accuracy (91.0%). We developed a novel deep-learning model to identify the attributes of calcified plaque and nodule. This model provided excellent diagnostic accuracy and agreement with the ground truth, thereby reducing the subjectivity of manual measurements and substantially saving time. These findings can help practitioners efficiently adopt appropriate therapeutic strategies to treat calcified lesions.

Morphological and Physiological Characteristics of Ruptured Plaques in Native Arteries and Neoatherosclerotic Segments: An OCT-Based and Computational Fluid Dynamics Study.

BackgroundIntravascular imaging has been used to assess the morphology of lesions causing an acute coronary syndrome (ACS) in native vessels (NV) and identify differences between plaques that ruptured (PR) and caused an event and those that ruptured without clinical manifestations. However, there is no data about the morphological and physiological characteristics of neoatherosclerotic plaques that ruptured (PR-NA) which constitute a common cause of stent failure.MethodsWe retrospectively analyzed data from patients admitted with an acute myocardial infarction that had optical coherence tomography (OCT) imaging of the culprit vessel before balloon pre-dilation. OCT pullbacks showing PR were segmented at every 0.4 mm. The extent of the formed cavity, lipid and calcific tissue, thrombus, and macrophages were measured, and the fibrous cap thickness (FCT) and the incidence of micro-channels and cholesterol crystals were reported. These data were used to reconstruct a representative model of the native and neoatherosclerotic lesion geometry that was processed with computational fluid dynamics (CFD) techniques to estimate the distribution of the endothelial shear stress and plaque structural stress.ResultEighty patients were included in the present analysis: 56 had PR in NV (PR-NV group) and 24 in NA segments (PR-NA group). The PR-NV group had a larger minimum lumen area (2.93 ± 2.03 vs. 2.00 ± 1.26 mm2, p = 0.015) but similar lesion length and area stenosis compared to PR-NA group. The mean FCT (186 ± 65 vs. 232 ± 80 μm, p = 0.009) and the lipid index was smaller (16.7 ± 13.8 vs. 25.9 ± 14.1, p = 0.008) while the of calcific index (8.3 ± 9.5 vs. 2.2 ± 1.6%, p = 0.002) and the incidence of micro-channels (41.4 vs. 12.5%, p = 0.013) was higher in the PR-NV group. Conversely, there was no difference in the incidence of cholesterol crystals, thrombus burden or the location of the rupture site between groups. CFD analysis revealed higher maximum endothelial shear stress (19.1 vs. 11.0 Pa) and lower maximum plaque structural stress (38.8 vs. 95.1 kPa) in the PR-NA compared to the PR-NV model.ConclusionWe reported significant morphological and physiological differences between culprit ruptured plaques in native and stented segments. Further research is needed to better understand the causes of these differences and the mechanisms regulating neoatherosclerotic lesion destabilization.

Impact of coronary plaque morphology on the precision of computational fractional flow reserve derived from optical coherence tomography imaging.

Computational fractional flow reserve (FFR) was recently developed to expand the use of physiology-guided percutaneous coronary intervention (PCI). Nevertheless, current methods do not account for plaque composition. It remains unknown whether the numerical precision of computational FFR is impacted by the plaque composition in the interrogated vessels. This study is an observational, retrospective, cross-sectional study. Patients who underwent both optical coherence tomography (OCT) and FFR prior to intervention between August 2011 and October 2018 at Wakayama Medical University Hospital were included. All frames from OCT pullbacks were analyzed using a deep learning algorithm to obtain coronary plaque morphology including thin-cap fibroatheroma (TCFA), lipidic plaque volume (LPV), fibrous plaque volume (FPV), and calcific plaque volume (CPV). The interrogated vessels were stratified into three subgroups: the overestimation group with the numerical difference between the optical flow ratio (OFR) and FFR >0.05, the reference group with the difference ≥-0.05 and ≤0.05, and the underestimation group with the difference <-0.05. In total 230 vessels with intermediate coronary artery stenosis from 193 patients were analyzed. The mean FFR was 0.82±0.10. Among them, 21, 179, and 30 vessels were in the overestimation, the reference, and the underestimation group, respectively. TCFA was higher in the underestimation group (60%) compared with reference (36.3%) and overestimation group (19%). Besides, it was not associated with numerical difference between OFR and FFR (NDOF) after multilevel linear regression. LPV was associated with NDOF as OFR underestimated FFR with -0.028 [95% confidence interval (CI): -0.047, -0.009] for every 100 mm3 increase in LPV. High lipid burden underestimates FFR when OFR is used to assess the hemodynamic importance of intermediate coronary artery stenosis. TCFA, FPV, and CPV were not independent predictors of NDOF.

Optical coherence tomography and coronary artery ectasia: the critical role of intracoronary imaging for optimal results of percutaneous coronary intervention

Percutaneous coronary intervention (PCI) in coronary artery ectasia is technically challenging, particularly regarding appropriate stent sizing, and it is associated with a higher incidence of adverse events. In this case report, a 63-year-old male patient, heart transplant recipient, underwent elective follow-up coronary angiography in the absence of clinical symptoms. Five years previously the patient was treated with coronary angioplasty and drug-eluting stent implantation for critical lesions of the left anterior descending coronary artery. Angiographic images showed a focal in-stent haziness at the level of an ectatic segment. To elucidate this finding, optical coherence tomography (OCT) was performed. Intracoronary imaging showed severe malapposition of the proximal end of the stent, with an intraluminal signal-rich structure, suggestive of organized stent thrombosis. Stent dilation was performed to maximal recommended diameter, with significant reduction of the malapposed area, as shown by repeated OCT pullbacks. Intracoronary imaging is particularly valuable in PCI of ectatic vessels to guide appropriate stent sizing and avoid stent malapposition. OCT, thanks to its superior spatial resolution in comparison with other intravascular imaging techniques, provides advantages for stent optimization and evaluation of stent failure causes. However, its limited imaging area and possible incomplete blood clearance may limit its usefulness in severely ectatic vessels.

Optical flow ratio for assessing stenting result and physiological significance of residual disease.

Optical flow ratio (OFR) is a novel method for fast computation of fractional flow reserve (FFR) from optical coherence tomography (OCT) images. We aimed to evaluate the accuracy of OFR in predicting post-percutaneous coronary intervention (PCI) FFR and the impact of stent expansion on within-stent OFR pressure drop (in-stent OFR). Post-PCI OFR was computed in patients with both OCT and FFR interrogation immediately after PCI. Calculation of post-PCI OFR (called simulated residual OFR) from pre-PCI OCT pullbacks after elimination of the stenotic segment by virtual stenting was performed in a subgroup of patients who had pre-PCI OCT images. Stent underexpansion was quantified by the minimum expansion index (MEI) of the stented segment. A total of 125 paired comparisons between post-PCI OFR and FFR were obtained in 119 patients, among which simulated residual OFR was obtained in 64 vessels. Mean post-PCI FFR was 0.92±0.05. Post-PCI OFR showed good correlation (r=0.74, p<0.001) and agreement (mean difference=-0.01±0.03, p=0.051) with FFR. The accuracy in predicting post-PCI FFR ≤0.90 was 84% for post-PCI OFR. Simulated residual OFR significantly correlated with post-PCI FFR (r=0.42, p<0.001). MEI showed a moderate correlation (r=-0.49, p<0.001) with in-stent OFR. Post-PCI OFR showed good diagnostic concordance with post-PCI FFR. Simulated residual OFR significantly correlated with post-PCI FFR. Stent underexpansion significantly correlated with in-stent pressure drop.

Abstract 12618: Feasibility of Non-Contrast Optical Coherence Tomography Imaging in Coronary Arteries

Background/Objectives: Contemporary high-resolution intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition to avoid signal attenuation by red blood cells. There is a growing need for an alternative flushing media other than iodine contrast to reduce the risk of renal dysfunction. To address this issue, we investigated the safety and feasibility of pentastarch solution as a flushing media for OCT image acquisition and compared with the contrast media flushed images. Methods/Results: We prospectively enrolled 12 patients with 15 coronary lesions (12 stented lesions and 3 non-culprit lesions). Paired OCT images were obtained by manual injection of iodine contrast (average 12 mL), followed by pentastarch (average 18-20 mL). A total of 30 runs were analyzed and each OCT pullback was assessed on a frame-by-frame basis by automated customized pixel-wise comparison algorithm. The number of clear image segments (CIS) and pre-specified quantitative measurements were compared between the paired OCT images. Image quality as assessed by proportion of CIS showed no significant difference between the contrast media and pentastarch (98.5% vs. 97.5%; p=0.850). Quantitative measurements including minimal lumen area, mean lumen area, and pixel-wise blood flushing capability correlated well between the paired image segments (p&lt;0.001) (Figure). There were no clinically relevant complications associated with OCT imaging with pentastarch administration such as anaphylactic reaction, life-threatening arrhythmia, heart failure, or acute renal deterioration. Conclusions: Intracoronary OCT using pentastarch is safe and technically feasible without affecting the optical signal intensity and overall image quality. Non-contrast imaging with pentastarch significantly reduces the obligatory iodine contrast load, therefore, could be considered as a promising strategy in high-risk patients for renal impairment.

Abstract 13099: Correlation of Lipoprotein(a) Levels With Coronary Plaque Morphological Features and Vulnerability: An Optical Coherence Tomography Study

Introduction: High lipoprotein(a) level is a potential independent risk factor for coronary artery disease (CAD). However, the relationship between the Lp(a) value and the morphological characteristics of plaque defined by optical coherence tomography (OCT) has not been completely clarified so far. Meanwhile, no evidence has been raised for a clear cut-off value of Lp(a) for preventing the process of CAD. Hypothesis: Based on the biological properties of Lp(a), We assessed the hypothesis that the Lp(a) levels may relate to the vulnerable features of lipid plaque defined by OCT. Methods: 420 CAD patients who had undergone OCT scan to at least 1 main coronary vessel during 2013-2018 were enrolled. Patients were first stratified into 3 levels according to the values of Lp(a) at admission: Lp(a)&lt;30 mg/dl (Group A), 30-60 mg/dl(Group B), and &gt;60 mg/dl(Group C). After enrolled the cases with Lp(a) &gt;60mg/dl, we chose cases of the other 2 groups matching according to traditional risk factors of CAD to our current analysis. OCT pullbacks of the target vessels were collected and analyzed at every 0.4 mm by 2 independent observers blinded to the clinical data and angiographies with QIVUS software. Results: A total of 90 cases were enrolled into the current study, with 30 cases in each group. Lipid plaque in Group B and Group C had a thinner minimum fibrous cap thickness, wider maximum lipid arc, longer lipid length, and greater lipid index than Group A. The Lp(a) levels significantly correlated with lipid length (r=0.283), the maximum arc of lipid(r=0.293), lipid index(r=0.357), and inversely correlated with minimum fibrous cap thickness (r =-0.403). Multivariate analysis demonstrated that the Lp(a) level was independently associated with TCFA (odds ratio 1.035, 95% confidence interval 1.014-1.057). In addition, the ROC curve analysis results (AUC =0.694, p &lt; 0.001) indicated the Lp(a) is a good diagnostic indicator for detecting TCFA, and the optimal cut-off was 33.65 mg/dl. Conclusions: Our current study indicates that CAD patients with higher Lp(a) level(&gt;30 mg/dl) exhibited a higher prevalence of TCFA and had more other typical vulnerable characteristics defined by OCT. New Lp(a) lowering therapy could aim at a level of &lt; 33.65mg/dl for stabilizing coronary plaque.

Stent detection with very thick tissue coverage in intravascular OCT.

Coronary stenting or percutaneous coronary intervention (PCI) is widely used to treat coronary artery disease. Improper deployment of stents may lead to post-PCI complication, in-stent restenosis, stent fracture and stent thrombosis. Intravascular optical coherence tomography (OCT) with micron-scale resolution provides accurate in vivo assessment of stent apposition/malapposition and neointima coverage. However, manual stent analysis is labor intensive and time consuming. Existing automated methods with intravascular OCT mainly focused on stent struts with thin tissue coverage. We developed a deep learning method to automatically analyze stents with both thin (≤0.3mm) and very thick tissue coverage (>0.3mm), and an algorithm to accurately analyze stent area for vessels with multiple stents. 25203 images from 56 OCT pullbacks and 41 patients were analyzed. Three-fold cross-validation demonstrated that the algorithm achieved a precision of 0.932±0.009 and a sensitivity of 0.939±0.007 for stents with ≤0.3mm tissue coverage, and a precision of 0.856±0.019 and a sensitivity of 0.874±0.011 for stents with >0.3mm tissue coverage. The correlation between the automatically computed and manually measured stent area is 0.954 (p<0.0001) for vessels with a single stent, and is 0.918 (p<0.0001) for vessels implanted with multiple stents. The proposed method can accurately detect stent struts with very thick tissue coverage and analyze stent area in vessels implanted with multiple stents, and can effectively facilitate the evaluation of stent implantation and post-stent tissue coverage.

Shape prior generation and geodesic active contour interactive iterating algorithm (SPACIAL): fully automatic segmentation for 3D lumen in intravascular optical coherence tomography images.

Fully automatic lumen segmentation in intravascular optical coherence tomography (OCT) images can assist physicians in quickly estimating the health status of vessels. However, OCT images are usually degraded by residual blood, catheter walls, guide wire artifacts, etc., which significantly reduce the quality of segmentation. To achieve accurate lumen segmentation in low-quality images, we propose a novel segmentation algorithm named SPACIAL: Shape Prior generation and geodesic Active Contour Interactive iterAting aLgorithm, which is guided by an adaptively generated shapeprior. In this framework, the active contour evolves under the guidance of shape prior, while the shape prior is automatically and adaptively generated based on the active contour. The active contour and the shape prior interactively iterate each other, which can generate the adaptive shape prior and consequently lead to accurate segmentation results. In addition, a fast algorithm is introduced to accelerate the segmentation in 3Dimages. The validity of the model is verified in 3240 images from 12 OCT pullbacks. The experimental results show satisfactory segmentation accuracy and time efficiency: the average Dice coefficient of SPACIAL is 93.6(2.4)%, and 5.7 times faster than that of the classical level setmethod. The proposed SPACIAL can quickly and efficiently perform accurate lumen segmentation on low quality OCT images, which is of great importance to cardiovascular disease diagnosis . The SPACIAL method shows great potential in clinicalapplications.

Acute Mechanical Performance of Magmaris vs. DESolve Bioresorbable Scaffolds in a Real-World Scenario.

Background: After the bioresorbable PLLA-based vascular scaffold (Absorb BVS) was taken from the market due to its high adverse event rates, a magnesium-based scaffold (Magmaris) was introduced.Objective: To compare the acute performance of the sirolimus-eluting magnesium alloy Magmaris scaffold with that of the novolimus-eluting PLLA-based DESolve scaffold in terms of appropriate scaffold deployment using optical coherence tomography (OCT).Methods and Results: Data from the final OCT pullback of 98 patients were included (19 Magmaris, 79 DESolve) and analyzed at 1-mm intervals. The following indices were calculated: mean and minimal area, residual area stenosis, incomplete strut apposition, tissue prolapse, eccentricity index, symmetry index, strut fracture, and edge dissection. OCT showed a minimum lumen area for Magmaris vs. DESolve of 6.6 ± 1.6 vs. 6.0 ± 1.9 (p = 0.06). Scaffolds with residual area stenosis >20% were predominantly seen in the DESolve group (15.8 vs. 46.8%; p = 0.01). The mean eccentricity index did differ significantly (0.74 ± 0.06 vs. 0.63 ± 0.09; p < 0.001). No fractures were observed for Magmaris scaffolds, but 15.2% were documented for DESolve BRS (p < 0.001). Incomplete scaffold apposition area was significantly higher in the DESolve group (0.01 ± 0.02 vs. 1.05 ± 2.32 mm2; p < 0.001).Conclusion: This is the first study to compare the acute mechanical performance between Magmaris and DESolve in a real-world setting. The acute mechanical performance of Magmaris BRS seems to be superior to that of DESolve BRS, whereas OCT showed a good acute mechanical performance for both BRS in terms of generally accepted imaging criteria.

TCTAP C-065 Longitudinal Stent Deformation Caused by Optical Coherence Tomography Pullback in Percutaneous Coronary Intervention

TCTAP C-065 Longitudinal Stent Deformation Caused by Optical Coherence Tomography Pullback in Percutaneous Coronary Intervention

Anatomical and functional healing after resorbable magnesium scaffold implantation in human coronary vessels: A combined optical coherence tomography and quantitative flow ratio analysis.

No data are currently available on the process of vessel healing and long-term physiological results after implantation of resorbable magnesium-made scaffold (RMS) in human coronary arteries. To investigate after percutaneous coronary intervention (PCI) and at 12 months follow-up (a) RMS resorption process and vessel healing, as judged by optical coherence tomography (OCT) imaging; and (b) physiological result of RMS implantation evaluated by quantitative flow ratio (QFR). All patients successfully treated with at least one RMS from July 2016 to August 2018 at 2 Italian centers were evaluated. All cases with OCT pullback and/or coronary angiography suitable for QFR analysis performed after PCI and at 12 months were included. Resorption process was analyzed at OCT in each frame reporting presence of residual struts in the vessel. Forty-four patients/forty-nine lesions were included. 12-months mean lumen area (LA; 7.54 ± 3.04 mm2 ) significantly decreased compared to mean LA recorded immediately after PCI (8.12 ± 1.89 mm2 ; p< .01). However, LA changes did not affect the functional result of PCI with a non-ischemic QFR value (>0.80) in 98% of cases at 12-months follow-up. Protruding struts were detectable in more than half of cases and their presence was correlated with an increase in mean LA (+0.73mm2 [95% CI 0.51-0.94], p< .001). RMS implantation in a real-world population lead to significant decrease in mean LA without significant functional impairment. Two different patterns of RMS resorption were recorded, whose clinical significance remains to be investigated.