Intravascular Ultrasound Imaging Research Articles

A Deep Learning-based Method to Extract Lumen and Media-Adventitia in Intravascular Ultrasound Images.

Intravascular ultrasound (IVUS) imaging allows direct visualization of the coronary vessel wall and is suitable for assessing atherosclerosis and the degree of stenosis. Accurate segmentation and lumen and median-adventitia (MA) measurements from IVUS are essential for such a successful clinical evaluation. However, current automated segmentation by commercial software relies on manual corrections, which is time-consuming and user-dependent. We aim to develop a deep learning-based method using an encoder-decoder deep architecture to automatically and accurately extract both lumen and MA border. Inspired by the dual-path design of the state-of-the-art model IVUS-Net, our method named IVUS-U-Net++ achieved an extension of the U-Net++ model. More specifically, a feature pyramid network was added to the U-Net++ model, enabling the utilization of feature maps at different scales. Following the segmentation, the Pearson correlation and Bland-Altman analyses were performed to evaluate the correlations of 12 clinical parameters measured from our segmentation results and the ground truth. A dataset with 1746 IVUS images from 18 patients was used for training and testing. Our segmentation model at the patient level achieved a Jaccard measure (JM) of 0.9080 ± 0.0321 and a Hausdorff distance (HD) of 0.1484 ± 0.1584 mm for the lumen border; it achieved a JM of 0.9199 ± 0.0370 and an HD of 0.1781 ± 0.1906 mm for the MA border. The 12 clinical parameters measured from our segmentation results agreed well with those from the ground truth (all p-values are smaller than .01). Our proposed method shows great promise for its clinical use in IVUS segmentation.

The Ever-Growing Field of High-Frequency Biomedical Ultrasound

Compared with other medical imaging counterparts, ultrasound has advantages owing to its real-time imaging capability, easy access, and cost-effectiveness. High-frequency (>20 MHz) ultrasound has been developed over the last few decades and is attractive because it provides high-resolution medical imaging and ultrasound backscattering microscopy (UBM) measurements, with applications targeting small animal imaging and some areas of human diagnosis. In recent years, driven by growing needs in intravascular ultrasound (IVUS) imaging, minimally invasive surgery, and particle manipulation, high-frequency ultrasound has continued to flourish as a niche modality and has expanded its important role in both diagnostic imaging and therapy. Concomitant needs have thus arisen in technological research and development to innovate materials, devices, algorithms, and systems for a variety of high-frequency ultrasound applications in medicine and biology.

Intravascular Ultrasound Confers No Benefit in Aortoiliac Revascularization

Endovascular interventions are a mainstay of treating aortoiliac occlusive disease. Intravascular ultrasound (IVUS) imaging offers unique information capable of identifying lesions missed by catheter angiography. The specific benefit of IVUS for aortoiliac interventions remains unclear as prior studies detail mixed outcomes. The purpose of this study is to evaluate the impact of IVUS on outcomes in endovascular interventions for aortoiliac occlusive disease.

P388 CORONARY PLAQUE CHARACTERISTICS ASSOCIATED WITH MAJOR ADVERSE CARDIOVASCULAR EVENTS AMONG ATHEROSCLEROTIC PATIENTS AND LESIONS: A SYSTEMATIC REVIEW AND META–ANALYSIS

Abstract Background The clinical value of coronary plaque characteristics (CPCs) to inform intensified medical therapy or revascularization of non–flow–limiting lesion remains uncertain. We performed a systematic review and meta–analysis to study the prognostic impact of CPCs comprehensively assessed with invasive and non–invasive imaging technologies on patient–level and lesion–level major cardiovascular adverse events (MACE). Methods We systematically reviewed MEDLINE, EMBASE, and the Cochrane database for studies evaluating the association of CPC with patient–level and lesion–level (MACE). CPCs included high plaque burden, low minimal lumen area, thin cap fibroatheroma, high lipid core burden index, low attenuation plaque, spotty calcification, napkin ring sign or positive remodelling. Results Thirty studies (21 retrospective, 9 prospective) with 30.369 patients were included. CPCs were evaluated by invasive intravascular techniques in 9 studies (optical coherence tomography=4, intravascular ultrasound imaging=3, near–infrared spectroscopy intravascular ultrasound imaging=2) and by coronary computed tomography angiography (CCTA) in 21 studies. CPCs were significantly predictive of patient–level and lesion–level MACE, also when only adjusted data where considered. For each CPC, the odds appeared higher for lesion–level (HR range 3.2–16.8) as compared to patient–level MACE (HR range 1.8–4.1). Accuracy was modest to moderate for most CPCs at the patient–level (AUC for MACE ranging between 0.53 and 0.84) and moderate to good for most CPCs at the lesion–level (AUC for MACE ranging between 0.71 and 0.83). Plaques with more than one CPC had the highest accuracy for lesion–level MACE (AUC 0.87, 95%CI 0.84–0.90). CPC pooled sensitivities for lesion–level MACE ranged between 40% and 63% and specificities between 73% and 98%. As the pooled prevalence of CPCs among plaques was low (3% to 28%), the estimated positive predictive values for lesion–level MACE were modest (range 33% to 45%). Conclusion CCTA and intravascular imaging characterization of CPCs provides independent prognostic value among atherosclerotic patients and lesions. However, the modest sensitivity and positive predictive value observed across all CPCs seem to suggest modest clinical value, especially to predict lesion–level events (PROSPERO identifier: CRD42021251810).

Predicting Coronary Stenosis Progression Using Plaque Fatigue From IVUS-Based Thin-Slice Models: A Machine Learning Random Forest Approach.

Introduction: Coronary stenosis due to atherosclerosis restricts blood flow. Stenosis progression would lead to increased clinical risk such as heart attack. Although many risk factors were found to contribute to atherosclerosis progression, factors associated with fatigue is underemphasized. Our goal is to investigate the relationship between fatigue and stenosis progression based on in vivo intravascular ultrasound (IVUS) images and finite element models. Methods: Baseline and follow-up in vivo IVUS and angiography data were acquired from seven patients using Institutional Review Board approved protocols with informed consent obtained. Three hundred and five paired slices at baseline and follow-up were matched and used for plaque modeling and analysis. IVUS-based thin-slice models were constructed to obtain the coronary biomechanics and stress/strain amplitudes (stress/strain variations in one cardiac cycle) were used as the measurement of fatigue. The change of lumen area (DLA) from baseline to follow-up were calculated to measure stenosis progression. Nineteen morphological and biomechanical factors were extracted from 305 slices at baseline. Correlation analyses of these factors with DLA were performed. Random forest (RF) method was used to fit morphological and biomechanical factors at baseline to predict stenosis progression during follow-up. Results: Significant correlations were found between stenosis progression and maximum stress amplitude, average stress amplitude and average strain amplitude (p < 0.05). After factors selection implemented by random forest (RF) method, eight morphological and biomechanical factors were selected for classification prediction of stenosis progression. Using eight factors including fatigue, the overall classification accuracy, sensitivity and specificity of stenosis progression prediction with RF method were 83.61%, 86.25% and 80.69%, respectively. Conclusion: Fatigue correlated positively with stenosis progression. Factors associated with fatigue could contribute to better prediction for atherosclerosis progression.

Effects of Metabolic Syndrome and SIRT1 Mutation on Store‐Operated Ca2+ Entry in Peripheral Blood Mononuclear Cells in Ossabaw Miniature Swine

BackgroundMetabolic syndrome (MetS) impairs sarco‐endoplasmic reticulum Ca2+ ATPase (SERCA) activity that may decrease the ER Ca2+ store and increase store‐operated Ca2+ entry (SOCE) in a variety of cell types. Similar Ca2+ signaling via SOCE causes fibrosis, vascular disease, and may trigger immunogenic (type 1) diabetes by action on peripheral blood mononuclear cells (PBMCs). Sirtuin 1 (SIRT1) is a deacetylase that maintains healthy metabolism and generally attenuates vascular disease. SIRT1 impairment exacerbates MetS and vascular disease by hyper‐acetylation of SERCA, decreasing its activity and thereby potentially increasing SOCE.HypothesisThe SIRT1 mutation made in Ossabaw miniature swine would mimic the mutation found in humans and increase PBMC SOCE.MethodsUsing CRISPR/Cas9 methodology a point mutation (SIRT1L100P) was made in Ossabaw miniature swine to mimic the naturally occurring mutation in humans and decrease SIRT1 activity, thereby resulting in hyperacetylation of Ca2+transporters and impaired function. Four groups of pigs were used to analyze genotype and diet interactions: wild type lean, SIRT1 lean, wild type MetS, and SIRT1 MetS. Pigs were age 4 months at the start and fed normal chow (lean) or atherogenic diet (MetS) for 7 months. PBMCs were isolated and Ca2+ was measured with fura‐2. The ER Ca2+store was depleted by 10‐5M cyclopiazonic acid to inhibit SERCA in a Ca2+‐free extracellular solution to fully deplete the ER Ca2+store and then Ca2+ was returned to the solution to induce maximal SOCE. Cells were recovered in Ca2+‐free solution to partially re‐fill the ER Ca2+ store, then Ca2+ returned to the solution to observe submaximal SOCE.ResultsBoth MetS diet groups (wild type MetS, SIRT1 MetS) showed impaired glucose tolerance. Fasting glucose in SIRT1 mutants was not different from wild type pigs, thus SIRT1 does not cause immunogenic diabetes at this early stage. Robust coronary atherosclerosis was shown by angiography, intravascular ultrasound, and gross imaging in MetS groups, but there was no additive or synergistic effect of SIRT1 mutation. There was no effect of MetS or SIRT1 mutation on maximal SOCE. Two‐way ANOVA showed that MetS diet increased submaximal SOCE (p&lt;0.009), but there was no effect of SIRT1 genotype on submaximal SOCE (p=0.266). The percentage of PBMCs that responded to partial ER Ca2+ depletion was 45% in lean pigs compared to 81% in wild type and 63% in SIRT1 pigs fed MetS diet.ConclusionSIRT1L100P mutation is likely to require longer duration to manifest robust effects on PBMC SOCE that were found with MetS diet. PBMC activation and can be easily studied longitudinally in the SIRT1L100P mutant swine model due to the ease of blood sampling.

Effect of Alirocumab Added to High-Intensity Statin Therapy on Coronary Atherosclerosis in Patients With Acute Myocardial Infarction

Coronary plaques that are prone to rupture and cause adverse cardiac events are characterized by large plaque burden, large lipid content, and thin fibrous caps. Statins can halt the progression of coronary atherosclerosis; however, the effect of the proprotein convertase subtilisin kexin type 9 inhibitor alirocumab added to statin therapy on plaque burden and composition remains largely unknown. To determine the effects of alirocumab on coronary atherosclerosis using serial multimodality intracoronary imaging in patients with acute myocardial infarction. The PACMAN-AMI double-blind, placebo-controlled, randomized clinical trial (enrollment: May 9, 2017, through October 7, 2020; final follow-up: October 13, 2021) enrolled 300 patients undergoing percutaneous coronary intervention for acute myocardial infarction at 9 academic European hospitals. Patients were randomized to receive biweekly subcutaneous alirocumab (150 mg; n = 148) or placebo (n = 152), initiated less than 24 hours after urgent percutaneous coronary intervention of the culprit lesion, for 52 weeks in addition to high-intensity statin therapy (rosuvastatin, 20 mg). Intravascular ultrasonography (IVUS), near-infrared spectroscopy, and optical coherence tomography were serially performed in the 2 non-infarct-related coronary arteries at baseline and after 52 weeks. The primary efficacy end point was the change in IVUS-derived percent atheroma volume from baseline to week 52. Two powered secondary end points were changes in near-infrared spectroscopy-derived maximum lipid core burden index within 4 mm (higher values indicating greater lipid content) and optical coherence tomography-derived minimal fibrous cap thickness (smaller values indicating thin-capped, vulnerable plaques) from baseline to week 52. Among 300 randomized patients (mean [SD] age, 58.5 [9.7] years; 56 [18.7%] women; mean [SD] low-density lipoprotein cholesterol level, 152.4 [33.8] mg/dL), 265 (88.3%) underwent serial IVUS imaging in 537 arteries. At 52 weeks, mean change in percent atheroma volume was -2.13% with alirocumab vs -0.92% with placebo (difference, -1.21% [95% CI, -1.78% to -0.65%], P < .001). Mean change in maximum lipid core burden index within 4 mm was -79.42 with alirocumab vs -37.60 with placebo (difference, -41.24 [95% CI, -70.71 to -11.77]; P = .006). Mean change in minimal fibrous cap thickness was 62.67 μm with alirocumab vs 33.19 μm with placebo (difference, 29.65 μm [95% CI, 11.75-47.55]; P = .001). Adverse events occurred in 70.7% of patients treated with alirocumab vs 72.8% of patients receiving placebo. Among patients with acute myocardial infarction, the addition of subcutaneous biweekly alirocumab, compared with placebo, to high-intensity statin therapy resulted in significantly greater coronary plaque regression in non-infarct-related arteries after 52 weeks. Further research is needed to understand whether alirocumab improves clinical outcomes in this population. ClinicalTrials.gov Identifier: NCT03067844.

Significance of Insignificant Left Main Disease

Significance of Insignificant Left Main Disease

Unsteady transport and two-phase binding of a drug in an atherosclerotic artery

To quantify the biology and physical understanding of endovascular drug delivery, a mathematical model that accounts for the two-phase binding of drug molecules in a diseased patient-specific artery has been developed. Using an image segmentation technique, the edges of the computational domain have been successfully extracted from an asymmetric intravascular ultrasound longitudinal image. The flow inside the porous tissue is described by the Brinkman model, and the luminal flow is Newtonian. At the lumen–tissue interface, an irreversible uptake kinetics for the injected drug from the luminal side into the tissue is taken into account. Furthermore, the drug's two-phase binding process, namely, the nonspecific binding caused by the drug's trapping in the extracellular medium (ECM-bound) and the specific binding caused by the interaction between drug molecules and receptors (REC-bound), has been considered. The Marker and Cell method has been leveraged to solve the governing equations numerically. Spatiotemporal variations of free drug, ECM-bound drug, and REC-bound drug are examined thoroughly for varying absorption parameter. Simulated results reveal that the interstitial flow amplifies drug distribution, retention, and delivery effectiveness, but flow separation downstream of the constriction reduces transmural flux. Concomitantly, the larger the absorption parameter, the higher the tissue content and effectiveness; nevertheless, significantly, larger absorption parameter values do not necessarily suggest improved delivery effectiveness. A thorough sensitivity analysis was carried out to predict the effects of some of the parameters involved.

Coronary Artery Radial Deformation and Velocity in Native and Stented Arteries.

Introduction Coronary arteries are exposed to a variety of complex biomechanical forces during a normal cardiac cycle. These forces have the potential to contribute to coronary stent failure. Recent advances in stent design allow for the transmission of native pulsatile biomechanical forces in the stented vessel. However, there is a significant lack of evidence in a human model to measure vessel motion in native coronary arteries and stent conformability. Thus, we aimed to characterize and define coronary artery radial deformation and the effect of stent implantation on arterial deformation. Materials and Methods Intravascular ultrasound (IVUS) pullback DICOM images were obtained from human coronary arteries using a coronary ultrasound catheter. Using two-dimensional speckle tracking, coronary artery radial deformation was defined as the inward and outward displacement (mm) and velocity (cm/s) of the arterial wall during the cardiac cycle. These deformation values were obtained in native and third-generation drug-eluting stented artery segments. Results A total of 20 coronary artery segments were independently analyzed pre and poststent implantation for a total of 40 IVUS runs. Stent implantation impacted the degree of radial deformation and velocity. Mean radial deformation in native coronary arteries was 0.1230 mm ± 0.0522 mm compared to 0.0775 mm ± 0.0376 mm in stented vessels (p=0.0031). Mean radial velocity in native coronary arteries was 0.1194 cm/s ± 0.0535 cm/s compared to 0.0840 cm/s ± 0.0399 cm/s in stented vessels (p=0.0228). Conclusion In this in vivo analysis of third-generation stents, stent implantation attenuates normal human coronary deformation during the cardiac cycle. The implications of these findings on stent failure and improved clinical outcomes require further investigation.

Observation of plaque behavior and tissue characterization of coronary plaque using speckle tracking intravascular ultrasound (ST-IVUS) and iMap imaging system.

Tissue characterization plays an important role in the development of acute coronary syndromes. iMap is an intravascular ultrasound (IVUS) tissue characterization system that provides useful information by reconstructing color-coded maps. Mechanical properties due to dynamic mechanical stress during a cardiac cycle may also trigger vulnerable plaque. Speckle tracking IVUS (ST-IVUS) has been introduced to observe plaque behavior in relation to mechanical properties. We report the case of an 84-year-old woman with stable coronary artery disease who underwent percutaneous coronary intervention, at which time IVUS demonstrated mainly three low echoic areas like lipid pools with thick fibrous caps. Pathological evaluation with iMap revealed that one low echoic area was occupied with necrotic tissue and that the other two areas occupied fibrotic. Although those tissue characterizations were different, they showed similar stretching behavior at systole by ST-IVUS which depicted plaque behavior from IVUS images using a color mapping. The mechanical properties of individual coronary plaques may differ depending on the tissue disposition. It is necessary to consider mechanical properties using ST-IVUS as well as to evaluate tissue characterization in plaque risk stratification.

Effect of Evolocumab on Coronary Plaque Phenotype and Burden in Statin-Treated Patients Following Myocardial Infarction

BackgroundThe proprotein convertase subtilisin kexin type-9 inhibitor evolocumab produced coronary atheroma regression in statin-treated patients. ObjectivesThe purpose of this study was to determine the effect of evolocumab on optical coherence tomography (OCT) measures of plaque composition. MethodsPatients with a non–ST-segment elevation myocardial infarction were treated with monthly evolocumab 420 mg (n = 80) or placebo (n = 81) for 52 weeks. Patients underwent serial OCT and intravascular ultrasound imaging within a matched arterial segment of a nonculprit vessel. The primary analysis determined the change in the minimum fibrous cap thickness and maximum lipid arc throughout the imaged arterial segment. Additional analyses determined changes in OCT features in lipid-rich plaque regions and plaque burden. Safety and tolerability were evaluated. ResultsAmong treated patients (age 60.5 ± 9.6 years; 28.6% women; low-density lipoprotein cholesterol [LDL-C], 141.3 ± 33.1 mg/dL), 135 had evaluable imaging at follow-up. The evolocumab group achieved lower LDL-C levels (28.1 vs 87.2 mg/dL; P < 0.001). The evolocumab group demonstrated a greater increase in minimum fibrous cap thickness (+42.7 vs +21.5 μm; P = 0.015) and decrease in maximum lipid arc (−57.5o vs. −31.4o; P = 0.04) and macrophage index (−3.17 vs −1.45 mm; P = 0.04) throughout the arterial segment. Similar benefits of evolocumab were observed in lipid-rich plaque regions. Greater regression of percent atheroma volume was observed with evolocumab compared with placebo (−2.29% ± 0.47% vs −0.61% ± 0.46%; P = 0.009). The groups did not differ regarding changes in microchannels or calcium. ConclusionsThe combination of statin and evolocumab after a non–ST-segment elevation myocardial infarction produces favorable changes in coronary atherosclerosis consistent with stabilization and regression. This demonstrates a potential mechanism for the improved clinical outcomes observed achieving very low LDL-C levels following an acute coronary syndrome. (Imaging of Coronary Plaques in Participants Treated With Evolocumab; NCT03570697)

Colocalization of Coronary Plaque with Wall Shear Stress in Myocardial Bridge Patients.

Patients with myocardial bridges (MBs) have a higher prevalence of atherosclerosis. Wall shear stress (WSS) has previously been correlated with plaque in coronary artery disease patients, but such correlations have not been investigated in symptomatic MB patients. The aim of this paper was to use a multi-scale computational fluid dynamics (CFD) framework to simulate hemodynamics in MB patient, and investigate the co-localization of WSS and plaque. We identified N = 10 patients from a previously reported cohort of 50 symptomatic MB patients, all of whom had plaque in the proximal vessel. Dynamic 3D models were reconstructed from coronary computed tomography angiography (CCTA), intravascular ultrasound (IVUS) and catheter angiograms. CFD simulations were performed to compute WSS proximal to, within and distal to the MB. Plaque was quantified from IVUS images in 2 mm segments and registered to CFD model. Plaque area was compared to absolute and patient-normalized WSS. WSS was lower in the proximal segment compared to the bridge segment (6.1 ± 2.9 vs. 16.0 ± 7.1 dynes/cm2, p value < 0.01). Plaque area and plaque burden measured from IVUS peaked at 1-3 cm proximal to the MB entrance, coinciding with the first diagonal branch. Normalized WSS showed a statistically significant moderate correlation with plaque area (r = 0.41, p < 0.01). WSS may be obtained non-invasively in MB patients and provides a surrogate marker of plaque area. Using CFD, it may be possible to non-invasively assess the extent of plaque area, and identify patients who could benefit from frequent monitoring or medical management.

Segmentation of intravascular ultrasound images based on convex–concave adjustment in extreme regions

Segmentation of intravascular ultrasound images based on convex–concave adjustment in extreme regions

Microvascular and Prognostic Effect in Lesions With Different Stent Expansion During Primary PCI for STEMI: Insights From Coronary Physiology and Intravascular Ultrasound.

BackgroundWhile coronary stent implantation in ST-elevation myocardial infarction (STEMI) can mechanically revascularize culprit epicardial vessels, it might also cause distal embolization. The relationship between geometrical and functional results of stent expansion during the primary percutaneous coronary intervention (pPCI) is unclear.ObjectiveWe sought to determine the optimal stent expansion strategy in pPCI using novel angiography-based approaches including angiography-derived quantitative flow ratio (QFR)/microcirculatory resistance (MR) and intravascular ultrasound (IVUS).MethodsPost-hoc analysis was performed in patients with acute STEMI and high thrombus burden from our prior multicenter, prospective cohort study (ChiCTR1800019923). Patients aged 18 years or older with STEMI were eligible. IVUS imaging, QFR, and MR were performed during pPCI, while stent expansion was quantified on IVUS images. The patients were divided into three subgroups depending on the degree of stent expansion as follows: overexpansion (>100%), optimal expansion (80%−100%), and underexpansion (<80%). The patients were followed up for 12 months after PCI. The primary endpoint included sudden cardiac death, myocardial infarction, stroke, unexpected hospitalization or unplanned revascularization, and all-cause death.ResultsA total of 87 patients were enrolled. The average stent expansion degree was 82% (in all patients), 117% (in overexpansion group), 88% (in optimal expansion), and 75% (in under-expansion). QFR, MR, and flow speed increased in all groups after stenting. The overall stent expansion did not affect the final QFR (p = 0.08) or MR (p = 0.09), but it reduced the final flow speed (−0.14 cm/s per 1%, p = 0.02). Under- and overexpansion did not affect final QFR (p = 0.17), MR (p = 0.16), and flow speed (p = 0.10). Multivariable Cox analysis showed that stent expansion was not the risk factor for MACE (hazard ratio, HR = 0.97, p = 0.13); however, stent expansion reduced the risk of MACE (HR = 0.95, p = 0.03) after excluding overexpansion patients. Overexpansion was an independent risk factor for no-reflow (HR = 1.27, p = 0.02) and MACE (HR = 1.45, p = 0.007). Subgroup analysis shows that mild underexpansion of 70%−80% was not a risk factor for MACE (HR = 1.11, p = 0.08) and no-reflow (HR = 1.4, p = 0.08); however, stent expansion <70% increased the risk of MACE (HR = 1.36, p = 0.04).ConclusionsStent expansion does not affect final QFR and MR, but it reduces flow speed in STEMI. Appropriate stent underexpansion of 70–80% does not seem to be associated with short-term prognosis, so it may be tolerable as noninferior compared with optimal expansion. Meanwhile, overexpansion and underexpansion of <70% should be avoided due to the independent risk of MACEs and no-reflow events.

Diagnostic performance of intravascular ultrasound-based fractional flow reserve versus angiography-based quantitative flow ratio measurements for evaluating left main coronary artery stenosis.

We compared the diagnostic performance of the ultrasonic flow ratio (UFR) and quantitative flow ratio (QFR) for left main coronary artery (LMCA) stenosis. Evaluation of LMCA stenosis remains challenging because of its complex pathogenesis and severity. Computing QFR allows rapid determination of fractional flow reserve (FFR) from coronary angiograms. A novel intravascular ultrasound (IVUS)-based FFR (UFR) allows rapid FFR computation from IVUS images. Neither of the computational approaches required a pressure wire or hyperemia induction. Previous studies have validated the good diagnostic accuracy of QFR and UFR in identifying hemodynamically significant coronary stenosis using FFR as the reference standard. This retrospective observational study enrolled consecutive patients with intermediate-grade LMCA stenosis who underwent IVUS evaluation. UFR and QFR of all LMCA stenosis patients were assessed, their correlation and agreement were analyzed, and diagnostic performance of UFR in LMCA stenosis was evaluated. Eighty-three paired comparisons between UFR and QFR were obtained. UFR excellently correlated with QFR (r = 0.74, p < 0.01). The Bland-Altman plot showed good agreement between UFR and QFR (mean differences: 0.01 ± 0.05, p = 0.34). The area under the curve of UFR for identifying physiological LMCA stenosis was 0.97 (95% confidence interval [CI]: 0.93-1.00, p < 0.01). The overall UFR diagnostic accuracy was 0.95 (95% CI: 0.88-0.99). UFR showed excellent correlation and good agreement with QFR in LMCA stenosis assessment, indicating that it is highly feasible to use UFR for functional evaluation of LMCA stenosis.

Three-Dimensional Intravascular Ultrasound Imaging Using a Miniature Helical Ultrasonic Motor.

Existing 3-D intravascular ultrasound (IVUS) systems that combine two electromagnetic (EM) motors to drive catheters are bulky and require considerable efforts to eliminate EM interference (EMI). Here, we propose a new scanning method to realize 3-D IVUS imaging using a helical ultrasonic motor to overcome the aforementioned issues. The ultrasonic motor with compact dimensions (7-mm outer diameter and 30-mm longitudinal length), lightweight (20.5 g), and free of EMI exhibits a great application potential in mobile imaging devices. In particular, it can simultaneously perform rotary and linear motions, facilitating precise 3-D scanning of an imaging catheter. Experimental results show that the signal-to-noise ratio (SNR) of raw images obtained using the ultrasonic motor is 5.3 dB better than that of an EM motor. Moreover, the proposed imaging device exhibits the maximum rotary speed of 12.3 r/s and the positioning accuracy of 2.6 [Formula: see text] at a driving voltage of 240 Vp-p. The 3-D wire phantom imaging and 3-D tube phantom imaging are performed to evaluate the performance of the imaging device. Finally, the in vitro imaging of a porcine coronary artery demonstrates that the layered architecture of the vessel can be precisely identified while significantly increasing the SNR of the raw images.

Alpha-Gal sensitization, mammalian meat consumption and allergic symptoms in adults from central Virginia at-risk for cardiovascular disease

Studying adults in central Virginia at-risk for cardiovascular disease we previously reported a high prevalence of α-Gal sensitization (26%) and, using high-sensitivity intravascular ultrasound imaging, an association between α-Gal IgE and coronary artery disease (CAD) severity. Here we sought to characterize diet and allergic symptoms in prospectively recruited at-risk subjects, hypothesizing that most sensitized subjects lacked allergic symptoms and routinely consumed mammalian meat.

Machine learning for atherosclerotic tissue component classification in combined near-infrared spectroscopy intravascular ultrasound imaging: Validation against histology

Background and aimsAccurate classification of plaque composition is essential for treatment planning. Intravascular ultrasound (IVUS) has limited efficacy in assessing tissue types, while near-infrared spectroscopy (NIRS) provides complementary information to IVUS but lacks depth information. The aim of this study is to train and assess the efficacy of a machine learning classifier for plaque component classification that relies on IVUS echogenicity and NIRS-signal, using histology as reference standard. MethodsMatched NIRS-IVUS and histology images from 15 cadaveric human coronary arteries were analyzed (10 vessels were used for training and 5 for testing). Fibrous/pathological intimal thickening (F-PIT), early necrotic core (ENC), late necrotic core (LNC), and calcific tissue regions-of-interest were detected on histology and superimposed onto IVUS frames. The pixel intensities of these tissue types from the training set were used to train a J48 classifier for plaque characterization (ECHO-classification). To aid differentiation of F-PIT from necrotic cores, the NIRS-signal was used to classify non-calcific pixels outside yellow-spot regions as F-PIT (ECHO-NIRS classification). The performance of ECHO and ECHO-NIRS classifications were validated against histology. Results262 matched frames were included in the analysis (162 constituted the training set and 100 the test set). The pixel intensities of F-PIT and ENC were similar and thus these two tissues could not be differentiated by echogenicity. With ENC and LNC as a single class, ECHO-classification showed good agreement with histology for detecting calcific and F-PIT tissues but had poor efficacy for necrotic cores (recall 0.59 and precision 0.29). Similar results were found when F-PIT and ENC were treated as a single class (recall and precision for LNC 0.78 and 0.33, respectively). ECHO-NIRS classification improved necrotic core and LNC detection, resulting in an increase of the overall accuracy of both models, from 81.4% to 91.8%, and from 87.9% to 94.7%, respectively. Comparable performance of the two models was seen in the test set where the overall accuracy of ECHO-NIRS classification was 95.0% and 95.5%, respectively. ConclusionsThe combination of echogenicity with NIRS-signal appears capable of overcoming limitations of echogenicity, enabling more accurate characterization of plaque components.

Key Technologies of New Type of Intravascular Ultrasound Image Processing.

Since entering the 21st century, the application of ultrasound technology has developed rapidly. Intravascular ultrasound technology has been widely used in the diagnosis and treatment of cardiovascular diseases. With the help of computer image processing technology, it can provide clinicians with more accurate diagnosis. Based on the information to improve the success rate of clinical treatment. Based on this, this article combines the development history of intravascular ultrasound technology, explores the principles of new intravascular ultrasound technology, and analyzes the application of new intravascular ultrasound technology. On this basis, the preprocessing of intravascular ultrasound image data is discussed, involving the acquisition of intravascular ultrasound image data and image analysis. On this basis, explore the combined application of new intravascular ultrasound technology and other imaging examination methods, such as X-rays to use three-dimensional image technology to reconstruct new intravascular ultrasound image sequences, and provide doctors with clearer morphology and properties of tube wall lesions. In order to make a more accurate diagnosis of the lesion, a more detailed and accurate treatment plan can be given, which has extremely high clinical application value.