Coronary artery atherectomy reduces plaque shear strains: an endovascular elastography imaging study.

Mechanical response and properties of the arterial wall can be used to identify the biomechanical instability of plaques and predict their vulnerability to rupture. Shear strain elastography (SSE) is proposed to identify vulnerable plaque features attributed to mechanical structural heterogeneities. The aims of this study were: 1) to report on the potential of SSE to identify atherosclerotic plaques; and 2) to use SSE maps to highlight biomechanical changes in lesion characteristics after directional coronary atherectomy (DCA) interventions.

ESTIMATION METHOD OF THE HOMODYNED K-DISTRIBUTION BASED ON THE MEAN INTENSITY AND TWO LOG-MOMENTS.

The homodyned K-distribution appears naturally in the context of random walks and provides a useful model for the distribution of the received intensity in a wide range of non-Gaussian scattering configurations, including medical ultrasonics. An estimation method for the homodyned K-distribution based on the first moment of the intensity and two log-moments (XU method), namely the and -statistics previously studied in the special case of the K-distribution, is proposed as an alternative to a method based on the first three moments of the intensity (MI method) or the amplitude (MA method), and a method based on the signal-to-noise ratio (SNR), the skewness and the kurtosis of two fractional orders of the amplitude (labeled RSK method). Properties of the and statistics for the homodyned K-distribution are proved, except for one conjecture.

Endovascular shear strain elastography for the detection and characterization of the severity of atherosclerotic plaques: in vitro validation and in vivo evaluation.

This work explores the potential of shear strain elastograms to identify vulnerable atherosclerotic plaques. The Lagrangian speckle model estimator (LSME) elasticity imaging method was further developed to estimate shear strain elasticity (SSE). Three polyvinyl alcohol cryogel vessel phantoms were imaged with an intravascular ultrasound (IVUS) scanner.

Non-invasive determination of left ventricular workload in patients with aortic stenosis using magnetic resonance imaging and Doppler echocardiography.

Early detection and accurate estimation of aortic stenosis (AS) severity are the most important predictors of successful long-term outcomes in patients. Current clinical parameters used for evaluation of the AS severity have several limitations including flow dependency. Estimation of AS severity is specifically challenging in patients with low-flow and low transvalvular pressure gradient conditions.

A PROOF OF CONVERGENCE OF THE HORN AND SCHUNCK OPTICAL FLOW ALGORITHM IN ARBITRARY DIMENSION.

The Horn and Schunck (HS) method, which amounts to the Jacobi iterative scheme in the interior of the image, was one of the first optical flow algorithms. In this article, we prove the convergence of the HS method, whenever the problem is well-posed. Our result is shown in the framework of a generalization of the HS method in dimension ≥ 1, with a broad definition of the discrete Laplacian.

Time-dependent hardening of blood clots quantitatively measured in vivo with shear-wave ultrasound imaging in a rabbit model of venous thrombosis.

Objective: Provide in vivo blood clot hardening evolution with ultrasound using supersonic imaging of shear waves.

Methods: We conducted a prospective study in flow stasis-induced venous thrombosis within jugular veins of white female New Zealand rabbits. Blood clot elasticity was noninvasively measured in vivo using the Young's modulus (in kilopascals), on a 2-hour and a 2-week periods after thrombus induction.

Interstitial lung diseases induced or exacerbated by DMARDS and biologic agents in rheumatoid arthritis: a systematic literature review.

Objective: To review published cases of induced or exacerbated interstitial lung disease (ILD) in rheumatoid arthritis (RA) associated with non-biologic disease-modifying antirheumatic drugs (nbDMARDs) and biologics and to discuss clinical implications in daily practice.

Methods: We performed a systematic literature review from 1975 to July 2013 using Medline, Embase, Cochrane, and abstracts from the ACR 2010-2012 and EULAR 2010-2013 annual meetings. Case reports and series that suggest a causative role of nbDMARDs (methotrexate [MTX], leflunomide [LEF], gold, azathioprine [AZA], sulfasalazine [SSZ], and hydroxychloroquine [HCQ]) and biologic agents (TNF inhibitors [TNFi], rituximab [RTX], tocilizumab [TCZ], abatacept [ABA], and anakinra) in causing ILD or worsening a pre-existing ILD in RA patients were included.

Segmentation method of intravascular ultrasound images of human coronary arteries.

The goal of this study was to show the feasibility of a 2D segmentation fast-marching method (FMM) in the context of intravascular ultrasound (IVUS) imaging of coronary arteries. The original FMM speed function combines gradient-based contour information and region information, that is the gray level probability density functions of the vessel structures, that takes into account the variability in appearance of the tissues and the lumen in IVUS images acquired at 40 MHz. Experimental results on 38 in vivo IVUS sequences yielded mean point-to-point distances between detected vessel wall boundaries and manual validation contours below 0.

A local angle compensation method based on kinematics constraints for non-invasive vascular axial strain computations on human carotid arteries.

Non invasive vascular elastography (NIVE) was developed to highlight atherosclerotic plaque constituents. However, NIVE motion estimates are affected by artifacts, such as an underestimation of deformations due to projected movement angles with respect to the ultrasound beam, movements of the operator or of the patient during image acquisition. The main objective of this work was to propose a local angle compensation method within small measurement windows for the axial strain based on kinematics constraints, and to introduce a filtering process on the strain time-varying curve to reduce as much as possible the impact of motion artifacts.

Fluid dynamics of coarctation of the aorta and effect of bicuspid aortic valve.

Up to 80% of patients with coarctation of the aorta (COA) have a bicuspid aortic valve (BAV). Patients with COA and BAV have elevated risks of aortic complications despite successful surgical repair. The development of such complications involves the interplay between the mechanical forces applied on the artery and the biological processes occurring at the cellular level.

Standardized evaluation methodology and reference database for evaluating IVUS image segmentation.

This paper describes an evaluation framework that allows a standardized and quantitative comparison of IVUS lumen and media segmentation algorithms. This framework has been introduced at the MICCAI 2011 Computing and Visualization for (Intra)Vascular Imaging (CVII) workshop, comparing the results of eight teams that participated. We describe the available data-base comprising of multi-center, multi-vendor and multi-frequency IVUS datasets, their acquisition, the creation of the reference standard and the evaluation measures.

Expression of peroxisome proliferator-activated receptors α, β, γ, and H- and L-prostaglandin D synthase during osteoarthritis in the spontaneous hartley guinea pig and experimental dog models.

Objective: To investigate the expression of peroxisome proliferator-activated receptors (PPAR) α, β, and γ, and hematopoietic and lipocalin-type prostaglandin D synthase (H- and L-PGDS) over the course of osteoarthritis (OA) in the spontaneous Hartley guinea pig and the anterior cruciate ligament transection dog models.

Methods: Guinea pigs were sacrificed at 2 (control group), 4, 8, and 12 months of age (n = 5 per group). Non-operated (control) and operated dogs were sacrificed at 4, 8, and 12 weeks postsurgery.

Dilatation of the bile duct in patients after cholecystectomy: a retrospective study.

Purpose: Retrospective assessment of impact of cholecystectomy, age, and sex on bile duct (BD) diameter.

Materials And Methods: We retrospectively reviewed abdominal contrast-enhanced multidetector computed tomography and laboratory reports of 290 consecutive patients (119 men; mean age, 55.9 years) who presented without cholestasis to the emergency department of our institution between June 2009 and August 2010.

Assessment of the effect of occupational exposure to formaldehyde on the risk of lung cancer in two Canadian population-based case-control studies.

Objective: This study aimed to explore the possible association between formaldehyde exposure and lung cancer risk.

Methods: Data were collected in two population-based case-control studies conducted in Montreal, Canada. Cases were individuals diagnosed with incident, histologically-confirmed lung cancer.

Cardiovascular adverse effects of anti-inflammatory drugs.

Anti-inflammatory drugs consist of non-steroidal anti-inflammatory drugs (NSAIDs) including non-selective nsNSAIDs, aspirin, and cyclooxygenase-2 (COX-2)-selective inhibitors also referred to as coxibs, and glucocorticoids (GCs). They are worldwide prescribed drugs for many musculoskeletal conditions, such as osteoarthritis and inflammatory rheumatic diseases. Anti-inflammatory drugs can exert deleterious effects on the cardiovascular system, excluding aspirin.

Biologics and the cardiovascular system: a double-edged sword.

Patients with chronic inflammatory diseases such as rheumatoid arthritis have a higher risk of cardiovascular diseases and related mortality compared to the general population. This risk is first due to classical cardiovascular risk factors but also due to systemic inflammation which is independently involved, causing accelerated atherosclerosis, myocardial infarction, cerebrovascular disease and heart failure (HF). Pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 and IL-6 could be major actors on this pathophysiology.

Effects of amphiphilic star-shaped poly(ethylene glycol) polymers with a cholic acid core on human red blood cell aggregation.

Elevated red blood cell (RBC) aggregation increases low-shear blood viscosity and is closely related to several pathophysiological diseases such as atherosclerosis, thrombosis, diabetes, hypertension, cancer, and hereditary chronic hemolytic conditions. Non-ionic linear polymers such as poly(ethylene glycol) (PEG) and Pluronic F68 have shown inhibitory effects against RBC aggregation. However, hypersensitivity reactions in some individuals, attributed to a diblock component of Pluronic F68, have been reported.

Shear wave induced resonance elastography of venous thrombi: a proof-of-concept.

Shear wave induced resonance elastography (SWIRE) is proposed for deep venous thrombosis (DVT) elasticity assessment. This new imaging technique takes advantage of properly polarized shear waves to induce resonance of a confined mechanical heterogeneity. Realistic phantoms (n = 9) of DVT total and partial clot occlusions with elasticities from 406 to 3561 Pa were built for in vitro experiments.

Risk of lung cancer associated with six types of chlorinated solvents: results from two case-control studies in Montreal, Canada.

Objectives: To determine whether exposure to various chlorinated solvents is associated with lung cancer.

Methods: Two case-control studies of occupation and lung cancer were conducted in Montreal, and included 2016 cases and 2001 population controls. Occupational exposure to a large number of agents was evaluated using a combination of subject-reported job history and expert assessment.

Velocity measurement accuracy in optical microhemodynamics: experiment and simulation.

Micro particle image velocimetry (µPIV) is a common method to assess flow behavior in blood microvessels in vitro as well as in vivo. The use of red blood cells (RBCs) as tracer particles, as generally considered in vivo, creates a large depth of correlation (DOC), even as large as the vessel itself, which decreases the accuracy of the method. The limitations of µPIV for blood flow measurements based on RBC tracking still have to be evaluated.

Shear wave induced resonance elastography of spherical masses with polarized torsional waves.

Shear Wave Induced Resonance (SWIR) is a technique for dynamic ultrasound elastography of confined mechanical inclusions. It was developed for breast tumor imaging and tissue characterization. This method relies on the polarization of torsional shear waves modeled with the Helmholtz equation in spherical coordinates.

A local increase in red blood cell aggregation can trigger deep vein thrombosis: evidence based on quantitative cellular ultrasound imaging.

Background: Recurrent deep vein thrombosis (DVT) risk factors include a first idiopathic DVT, strongly suggesting the existence of undiagnosed and/or unidentified prothrombotic abnormalities.

Objectives: To evaluate the impact of locally increased red blood cell (RBC) aggregation on DVT pathogenesis in a rabbit model.

Methods: DVT presence, flow and aggregation were measured in situ with ultrasound.

A critical review and uniformized representation of statistical distributions modeling the ultrasound echo envelope.

In ultrasound imaging, various statistical distributions have been proposed to model the first-order statistics of the amplitude of the echo envelope. We present an overview of these distributions based on their compound representation, which comprises three aspects: the modulated distribution (Rice or Nakagami); the modulating distribution (gamma, inverse Gaussian or even generalized inverse Gaussian); and the modulated parameters (the diffuse signal power with or without the coherent signal component or the coherent signal power). This unifying point of view makes the comparison of the various models conceptually easier.

Shear wave induced resonance elastography of soft heterogeneous media.

In the context of ultrasound dynamic elastography imaging and characterization of venous thrombosis, we propose a method to induce mechanical resonance of confined soft heterogeneities embedded in homogenous media. Resonances are produced by the interaction of horizontally polarized shear (SH) waves with the mechanical heterogeneity. Due to such resonance phenomenon, which amplifies displacements up to 10 times compared to non-resonant condition, displacement images of the underlying structures are greatly contrasted allowing direct segmentation of the heterogeneity and a more precise measurement of displacements since the signal-to-noise ratio is enhanced.