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We developed a deep learning (DL) model for automated atherosclerotic plaque categorization using optical frequency domain imaging (OFDI) and performed quantitative and visual evaluations. A total of 1103 histological cross-sections from 45 autopsy hearts were examined to compare the ex vivo OFDI scans. The images were segmented and annotated considering four histological categories: pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), and healed erosion/rupture (HER). The DL model was developed based on pyramid scene parsing network (PSPNet). Given an input image, a convolutional neural network (ResNet50) was used as an encoder to generate feature maps of the last convolutional layer. For the quantitative evaluation, the mean F-score and IoU values, which are used to evaluate how close the predicted results are to the ground truth, were used. The validation and test dataset had F-score and IoU values of 0.63, 0.49, and 0.66, 0.52, respectively. For the section-level diagnostic accuracy, the areas under the receiver-operating characteristic curve produced by the DL model for FC, PIT, FA, and HER were 0.91, 0.85, 0.86, and 0.86, respectively, and were comparable to those of an expert observer. DL semantic segmentation of coronary plaques in OFDI images was used as a tool to automatically categorize atherosclerotic plaques using histological findings as the gold standard. The proposed method can support interventional cardiologists in understanding histological properties of plaques. [Display omitted] • A deep learning (DL) model for automated classification of optical frequency domain imaging (OFDI) was developed. • It can provide accurate categorization of the atherosclerotic coronary plaque type. • This model can support interventional cardiologists in catheterization laboratory. [ABSTRACT FROM AUTHOR]

The development of peri-stent contrast staining (PSS) after coronary intervention with implantation of a stent is observed in approximately 1–3% of patients treated with drug-eluting stent. Although the cumulative incidences of late in-stent restenosis and stent thrombosis are significantly higher in lesions with PSS than in those without the finding, the mechanisms for the development of PSS have not yet been fully elucidated. In this report, we describe a case of rapid development of PSS with ulcer formation caused by rupture of atherogenic neointima, which was observed by serial optical coherence tomography examinations over 6 months. Protrusion of the stent-jailed underlying necrotic core toward the lumen by the contracting force might have resulted in formation of atherogenic neointima within the stent. Subsequently, rupture of this necrotic core induced by iatrogenic neointimal injury due to balloon dilation and dissolution of the accumulated necrotic core may have resulted in PSS formation 6 months after the procedure. These findings may be helpful for consideration of etiology and therapeutic strategy for lesions with PSS. < Learning objective: The mechanisms of peri-stent contrast staining (PSS) formation late after drug-eluting stent (DES) implantation are diverse. Rupture of atherogenic neointima with subsequent dissolution of the stent-jailed underlying plaque debris could be one of the mechanisms of rapid PSS formation after implantation of DES. An accurate assessment of lesion morphology within the stent and patient-tailored management can reduce morbidity and mortality in patients who have undergone DES implantation.> [ABSTRACT FROM AUTHOR]

• The present study compared ex vivo optical frequency domain imaging (OFDI) with histological diagnosis. • The overall agreement correlated with the observers' years of experience. • The interpretation of OFDI scans requires expertise. To date, there have been no data available regarding the diagnostic performance of optical frequency domain imaging (OFDI) for in vivo histological classification of atherosclerotic lesions. This study investigated whether OFDI can be used to diagnose and classify histological atherosclerotic lesions in the coronary artery by ex vivo histological examinations. Three-hundred-fifteen histological cross-sections from 21 autopsy hearts were matched with the OFDI images. Histological cross-sections were classified into six categories: adaptive intimal thickening (AIT), pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), calcified nodule, and healed erosion/rupture. The five observers with different years of experience in the interpretation of OFDI provided a single diagnosis for the OFDI scans of each cross-section according to the aforementioned six histological categories. The diagnostic accuracy and interobserver variability of lesion types for each OFDI observer were determined using histology as the gold standard. The overall agreement rates between OFDI and histopathologic diagnosis for OFDI observers 1–5 were 81%, 70%, 68%, 61%, and 50% (κ values of 0.75, 0.61, 0.58, 0.49, and 0.36), respectively. Although the diagnostic accuracy of OFDI for detecting AIT and FC was excellent for all five observers, the sensitivity, and positive predictive values of OFDI for detecting PIT and FA were low in proportion to years of experience. The diagnostic accuracy of atherosclerotic tissue properties from OFDI scans correlated with the observers' years of experience, especially when lesions contained lipid components. [ABSTRACT FROM AUTHOR]

Optical coherence tomography (OCT), a catheter-based imaging modality for the visualization of coronary arteries, is widely used during percutaneous coronary intervention to improve the understanding of the anatomy of coronary artery stenosis and to elucidate the mechanisms of atherosclerosis. In this review, we provide a short description of the histopathological validations of OCT for visualizing atherosclerotic plaques and vascular healing response after drug-eluting stent (DES) implantation. Because OCT measures the intensity of light returning from within a tissue, tissue having a higher heterogeneity of optical index of refraction, such as microcalcification deposition and foam cell accumulation on the luminal surface, may exhibit stronger optical scattering that appears as a thin-cap fibroatheroma image. Furthermore, even if OCT shows exposed uncovered stent struts, some of the struts could be re-endothelialized. In our ex vivo histopathological experience, re-endothelialization at the surface of stent struts was confirmed by histopathological analysis, although OCT images showed exposed uncovered struts after DES implantation. Therefore, careful interpretation is required to assess tissue morphology and stent strut coverage by OCT. [ABSTRACT FROM AUTHOR]

Background The optimal sizing of self-expanding paclitaxel-eluting stents (PES) in the treatment for superficial femoral artery (SFA) lesions is unclear. This study sought to investigate the influence of PES diameter on stent patency in SFA lesions using optical frequency domain imaging (OFDI). Methods A total of 20 de novo SFA lesions were randomized 1:1 to receive either self-expanding PES with a nominal diameter of 6 mm or 8 mm. Follow-up angiography and OFDI was scheduled six months after stent implantation, and volumetric OFDI analysis was performed to evaluate vascular response to the stents. Volume index (VI) was defined as the volume divided by the stent length. The primary end point was lumen VI at the 6-month follow-up. Secondary end point was minimum lumen diameter (MLD) by quantitative vascular angiography (QVA) at the follow-up. Results Stent length was 78.0 ± 23.9 mm in the 6-mm group and 70.0 ± 23.6 mm in the 8-mm group ( p = 0.46). Baseline QVA data were also similar between the two groups. MLD immediately after stent implantation was similar between the two groups (4.2 ± 0.5 mm in the 6-mm group and 3.9 ± 0.5 mm in the 8-mm group, p = NS). At the 6-month follow-up, MLD was greater in the 8-mm group compared to the 6-mm group (4.0 ± 1.0 mm vs. 3.2 ± 0.4 mm, p < 0.05). Stent VI was larger in the 8-mm group (28.4 ± 6.7 mm 3 /mm vs. 22.2 ± 1.2 mm 3 /mm, p = 0.01). Neointimal VI was similar between the two groups (5.8 ± 2.9 mm 3 /mm vs. 5.2 ± 2.6 mm 3 /mm, p = 0.68). Lumen VI was greater in the 8-mm group (23.2 ± 7.6 mm 3 /mm vs. 17.3 ± 2.6 mm 3 /mm, p = 0.04). Conclusions Chronic stent enlargement resulted in greater lumen area after implantation of self-expanding PES with a large diameter at the mid-term follow-up. Stent diameter might be important for stent patency in procedure with PES for SFA lesions. [ABSTRACT FROM AUTHOR]

Background We sought to clarify the impact of final kissing inflation (FKI) after single stenting of bifurcation lesions on vessel healing. Methods From the J-REVERSE registry enrolling 303 bifurcation lesions treated with provisional single stenting using sirolimus- (SES) or everolimus-eluting stent (EES), 65 lesions treated with ( n = 30) and without ( n = 35) FKI underwent 9-month follow-up optical coherence tomography. Average stent eccentricity index (SEI: minimum/maximum stent diameter) and neointimal unevenness score (NUS: maximum/average neointimal thickness of the same cross-section) for the proximal, bifurcation, and distal segments were compared between FKI and non-FKI groups. Results At the proximal segment, the FKI group demonstrated significantly larger average stent area with greater asymmetric stent expansion, and average lumen area remained significantly larger at 9-month follow-up despite a tendency toward greater neointimal proliferation. Jailed strut and thrombus incidence were also significantly lower at the side branch orifice, and NUS was significantly smaller at the bifurcation and proximal segments in the FKI group. Conclusions Nine months after SES and EES treatment of bifurcation lesions, FKI reduced proximal-segment luminal narrowing. Considering its homogeneous neointimal distribution and fewer jailed struts, FKI may be beneficial for treating bifurcation lesions. [ABSTRACT FROM AUTHOR]

Background Optical coherence tomography (OCT) is one of the tools trying to distinguish neoatherosclerosis from other neointimal tissue but its role has to be still validated. This study evaluated the diagnostic accuracy of OCT for characterization of lipid-atherosclerotic neointima following drug-eluting stent (DES) implantation. Methods Twelve stented coronary arteries from the 7 autopsy hearts were imaged by OCT. These OCT images were compared with histology. By OCT, the morphological appearances of neointima were classified into three patterns: homogeneous pattern, heterogeneous pattern with visible strut, or heterogeneous pattern with invisible strut. Results Of 21 histological cross-sections, 6 were categorized as homogeneous patterns (29%), 11 as heterogeneous patterns with visible stent strut (52%), and 4 as heterogeneous patterns with invisible stent strut (19%). All homogeneous patterns were composed of smooth muscle cells with collagen fibers. The heterogeneous patterns with visible stent strut included proteoglycan-rich myxomatous matrix and calcium deposition. On the other hand, the heterogeneous patterns with invisible stent strut comprised atheromatous tissue, including a large amount of foam cell accumulation (25%) or large fibroatheroma/necrotic core (75%) inside the stent struts within neointima. The optical attenuation coefficient was highest in the heterogeneous pattern with invisible stent strut due to scattering of light by atheromatous tissue. Conclusion The heterogeneous patterns with invisible stent strut on OCT imaging identify the presence of lipid-atherosclerotic tissue within neointima after DES. This may suggest the potential capability of OCT based on visualization of stent struts for discriminating atheromatous formation within neointima from other neointimal tissue. [ABSTRACT FROM AUTHOR]

Background Zotarolimus-eluting stents (ZES) have a higher rate of neointimal coverage than the first-generation drug-eluting stents on optical coherence tomography (OCT). Objective To determine whether neointimal coverage of stent struts detected by OCT can be used as a surrogate for endothelial function after ZES implantation. Design Cross-sectional observational study. Setting Three months after ZES implantation. Patients and methods OCT was performed in 20 patients with a ZES at 3 months after stent implantation to evaluate strut coverage. Endothelium-dependent coronary vasomotion was estimated by infusing incremental doses of acetylcholine into the coronary ostium. The vascular response was measured in the 10 mm segments proximal and distal to the stent. Results Of 20 ZES, 15 (75%) were covered completely with neointima, but the remaining 5 ZES had exposed struts. The high-dose acetylcholine infusion produced significant vasoconstriction in the proximal ( -- 9.8±10.1%) and the distal stent segment (-- 29.7±22.7%). However, the degree of vasoconstriction to acetylcholine varied between individuals (from -- 0.6% to -- 77%). Although no relationship was observed between coronary vasomotor response (percentage change in diameter after acetylcholine administration) and average neointimal thickness, the number of cross-sections with uncovered struts showed an inverse correlation with coronary vasomotor response in proximal and distal stent segments (r= -- 0.57, p=0.007 and r= -- 0.83, p<0.001, respectively). Conclusions The existence of exposed struts was associated with abnormal vasoconstriction to acetylcholine at 3 months after ZES implantation. The findings suggest that complete neointimal coverage of stent struts assessed by OCT could be used as a surrogate for vasomotion impairment at 3 months after ZES implantation. [ABSTRACT FROM AUTHOR]

Objectives: We evaluated the geographic distribution of thin-cap fibroatheromas (TCFAs) in the coronary arteries using optical coherence tomography (OCT), a high-resolution imaging modality. Background: Plaque rupture is the most frequent cause of acute myocardial infarction (AMI). It has been recognized that TCFA is the primary plaque type at the site of plaque rupture. Methods: We performed 3-vessel OCT examinations in 55 patients: 35 AMI and 20 stable angina pectoris patients. The criteria for TCFA in an OCT image was a lipid-rich plaque with fibrotic cap thickness <65 μm. The distance between each TCFA location and the respective coronary artery ostium was measured with motorized OCT imaging pullback. The total length of all 3 coronary arteries imaged by OCT pullbacks was 82 ± 21 mm in the left anterior descending coronary artery (LAD), 67 ± 26 mm in the left circumflex coronary artery (LCx), and 104 ± 32 mm in the right coronary artery (RCA). Results: OCT detected 94 TCFAs in 165 coronary arteries. The minimum fibrous-cap thickness of TCFAs was 57.4 ± 5.4 μm in AMI patients, and 55.9 ± 7.3 μm in stable angina pectoris patients (p = 0.4). Of the total of 94 TCFAs, 28 were detected in the LAD, 18 in the LCx, and 48 in the RCA. Most LAD TCFAs were located between 0 and 30 mm from the LAD ostium (76%). Conversely, LCx and RCA TCFAs were evenly distributed throughout the entire coronary length. The clustering of the TCFAs was similar in culprit segments as compared with nonculprit segments. In AMI patients, most LAD TCFAs were distributed near side branches, mainly positioned opposite the side branch bifurcation. Conclusions: Three-vessel OCT imaging showed that TCFAs tend to cluster in predictable spots within the proximal segment of the LAD, but develop relatively evenly in the LCx and RCA arteries. [Copyright &y& Elsevier]

Summary: Late-acquired angiographic coronary aneurysm formation after drug-eluting stent implantation is a rare phenomenon but potentially life-threatening event that has become a major cause of concern. Optical coherence tomography (OCT) is a high-resolution imaging method that allows detailed evaluation of stent strut coverage and characterization of neointimal tissue. This case report describes the possible mechanism of late-acquired angiographic coronary aneurysm formation after bare-metal stent implantation using OCT and intravascular ultrasound. [ABSTRACT FROM AUTHOR]