Background: Heart failure with preserved ejection fraction continues to pose multiple challenges in terms of accurate diagnosis, treatment, and associated morbidity. Accurate left ventricular (LV) mass calculation yields essential... more
Background: Heart failure with preserved ejection fraction continues to pose multiple challenges in terms of accurate diagnosis, treatment, and associated morbidity. Accurate left ventricular (LV) mass calculation yields essential prognostic information relating to structural heart disease. Two-dimensional (2D) echocardiography-based calculations are solely limited to LV geometric assumptions of symmetry, whereas three-dimensional (3D) echocardiography could overcome these limitations. This study aims to compare the performance of 2D and 3D LV mass calculations.Methods: A prospective review of echocardiography findings at the University of Louisville, Kentucky, was conducted and assessed. Normal ejection fraction (EF) was defined as >=52% in males and >=54% in females. The following calculations were performed: relative wall thickness (RWT) = 2x posterior wall thickness/LV internal diastolic dimension (LVIDd) and 2D LV mass = 0.8{1.04([LVIDd + IVSd +PWd]3 - LVIDd3)} + 0.6. Con...
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In this paper we propose a deep learning framework to estimate pressure from 4D flow MRI. Pressure drop is an important parameter to detect and diagnose different cardiovascular diseases. Accurate estimation of pressure from 4D flow MRI... more
In this paper we propose a deep learning framework to estimate pressure from 4D flow MRI. Pressure drop is an important parameter to detect and diagnose different cardiovascular diseases. Accurate estimation of pressure from 4D flow MRI is hampered however due to noise and low resolution of 4D flow data. In the proposed method we consider the pressure estimation as a mapping function between velocity to pressure and employ an encoder-decoder based deep network for the mapping. A computational fluid dynamic model was designed which identically matched the geometry of a stenotic flow phantom used in 4D Flow MRI experiments and velocity and pressure data was simulated for 1000 different flow conditions to train the network. In addition, the proposed network was tested on real in -vitro 4D flow MRI in the same stenotic model for 3 different flow rates. Estimated pressures from the network showed excellent agreement with the reference CFD simulated pressures. As measure of fidelity, rela...
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The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on tissue Doppler imaging (TDI) or... more
The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on tissue Doppler imaging (TDI) or speckle tracking. These methods are based on two techniques which to a large degree are independent: the Doppler phenomenon and image sequence processing. Herein, to increase the accuracy of the speckle tracking technique and to cope with the angle dependence of TDI, a combined approach dubbed tissue Doppler imaging optical flow (TDIOF) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms minimized using algebraic equations and is validated on simulated images, and in vivo data. It was observed that the additional Doppler term is able to increase the accuracy of speckle tracking, compared to two popular motion estimation and speckle tracking techniques (Horn-Schunck and block matching methods). This observation was more pronounced when noise was present. The magnitude and angular error for TDIOF applied to simulated images, when comparing estimated motion with ground-truth motion, were 15% and 9.2°/frame, respectively. As an additional validation, echocardiography-derived strains were compared to tagged MRI-derived myocardial strains in the same subjects. The correlation coefficient (r) between the TDIOF-derived radial strains and tagged MRI-derived radial strains value was 0.83 (P < 0.001). The correlation coefficient ( r) for the TDIOF-derived circumferential strains compared to the tagged MRI-derived circumferential strains was 0.86 (P < 0.001). The comparison of TDIOF-derived and block matching speckle tracking and Horn-Schunck optical flow strain values using student t-test demonstrated superiority of TDIOF (95% confidence interval, P < 0.001).
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Research Interests: Cardiology, Medicine, Echocardiography, Congenital Heart Defects, Humans, and 15 moreInternal Medicine, Bicuspid Aortic Valve, Female, Male, Differential Diagnosis, Artifacts, Aged, Calcinosis, Adult, Diagnostic Accuracy, Cardiomyopathies, Aortic Valve, Calcification, Bicuspid Valve, and Cardiovascular medicine and haematology
Measurement of cardiac output is a clinically valuable and widely used index of cardiac function. Although transesophageal echocardiography has been used to assess left ventricular function, little data exist on the accuracy of this... more
Measurement of cardiac output is a clinically valuable and widely used index of cardiac function. Although transesophageal echocardiography has been used to assess left ventricular function, little data exist on the accuracy of this technique in the measurement of cardiac output. Therefore cardiac output derived by pulsed Doppler transesophageal echocardiography and thermodilution methods were compared in adult patients being mechanically ventilated. The left ventricular outflow tract diameter was determined from a transgastric long-axis view of the left ventricle by using the transverse plane and longitudinal plane of the transesophageal scope. The cross-sectional area of the left ventricular outflow tract was calculated from the diameter assuming a circular shape. Pulsed Doppler recordings were obtained at the left ventricular outflow tract. Doppler time-velocity integrals were measured from the leading edge of the velocity curve. Cardiac output derived by transesophageal echocardiography was calculated as time-velocity integral multiplied by left ventricular outflow tract area and heart rate. Cardiac output derived by transesophageal echocardiography from the transverse plane (n = 26) and longitudinal plane (n = 22) were correlated with simultaneous thermodilution measurements. Thermodilution-derived cardiac output demonstrated excellent correlation with cardiac output measured by using transesophageal echocardiography from the transverse plane (r = 0.97, SEE = 0.84 L/min; p < 0.0001) and longitudinal plane (r = 0.95, SEE = 0.97 L/min; p < 0.0001). Transesophageal echocardiography is a promising technique in the measurement of cardiac output and expands the clinical use of this modality in the assessment of cardiac function.
Research Interests: Cardiology, Medicine, Humans, Internal Medicine, Female, and 15 moreFeasibility Studies, Male, Aged, Middle Aged, Observer Variation, Adult, Public health systems and services research, Cardiac Output Monitoring, Doppler effect, Reproducibility of Results, Critical Illness, cardiac cycle, Cardiac output, Cardiovascular medicine and haematology, and ventricle
Research Interests: Cardiology, Medicine, Echocardiography, Humans, Internal Medicine, and 15 moreAortic stenosis, Female, Feasibility Studies, Male, Mitral Valve Repair, Clinical Sciences, Aged, Cardiac Catheterization, Middle Aged, Adult, Esophagus, Aortic Valve, Aortic valve stenosis, Cardiovascular medicine and haematology, and Doppler echocardiography
Atrial pacing and dipyridamole transesophageal echocardiography have been shown to be sensitive and specific tests for the detection of coronary artery disease. However, the sensitivity and specificity of dobutamine transesophageal... more
Atrial pacing and dipyridamole transesophageal echocardiography have been shown to be sensitive and specific tests for the detection of coronary artery disease. However, the sensitivity and specificity of dobutamine transesophageal echocardiography have not been reported. The purpose of this study was to determine the feasibility, sensitivity, and specificity of dobutamine transesophageal echocardiography for the detection of coronary artery disease. Transesophageal echocardiographic assessment of left ventricular function was performed in 81 adult patients aged 62 +/- 12 years during stepwise infusion of dobutamine from 5.0 to 40 micrograms/kg/min. Ischemia was diagnosed by the development of severe hypokinesis, akinesis, or dyskinesis of a previously contractile left ventricular segment. Coronary artery disease was defined by angiography as a reduction in luminal diameter of > or = 70% of an epicardial or > or = 50% of the left main coronary artery. In patients who had undergone coronary artery bypass graft surgery, a stenotic bypass graft was defined as a reduction in luminal diameter of > or = 70%. In patients without previous CABG, significant coronary artery disease was present in 21 patients: 5 with single-vessel disease, 7 double-vessel disease, 8 triple-vessel disease, and 1 left main coronary disease. Dobutamine transesophageal echocardiography had a sensitivity of 90% (19 of 21) and specificity of 94% (49 of 52) for the detection of coronary artery disease. In patients with previous CABG (n = 8), the sensitivity and specificity for the detection of bypass graft stenosis were 100% (4 of 4) and 75% (3 of 4), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Research Interests: Cardiology, Medicine, Electrocardiography, Echocardiography, Humans, and 15 moreInternal Medicine, Blood Pressure, Female, Feasibility Studies, Male, Aged, Middle Aged, Coronary Angiography, Adult, Coronary heart disease, Public health systems and services research, Exercise Test, Myocardial Ischemia, Cardiovascular medicine and haematology, and Coronary Vessels
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Introduction: The presence of gastroesophageal varices (GEV) is considered a relative contraindication to performing Trans esophageal echocardiography (TEE) however; the safety of TEE in patients with GEV is unknown. Hypothesis: Bleeding... more
Introduction: The presence of gastroesophageal varices (GEV) is considered a relative contraindication to performing Trans esophageal echocardiography (TEE) however; the safety of TEE in patients with GEV is unknown. Hypothesis: Bleeding complications related to TEE in patients with GEV are dependent on the severity of the GEV. Methods: 55 patients (G1) with GEV undergoing clinically indicated TEE were studied. Each patient was matched by age and gender to a control subject (C). GEV were graded using esophagogastroduodenoscopy (EGD). There were 39 males and 16 females in either group. Complications related to TEE were defined as upper gastrointestinal (GI) bleed, decline in hemoglobin by more than 2 g/dl, esophageal perforation, aspiration, respiratory compromise requiring intubation and/or need for sedative reversal agents that occurred within 48 hours of the procedure. Results: In G1 grade 1, grade 2, and grade 3 GEV were present in 21, 24, and 12 patients, respectively. Of the 12...
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Background and Purpose: It is unknown when to start anticoagulation after acute ischemic stroke (AIS) from atrial fibrillation (AF). Early anticoagulation may prevent recurrent infarctions but may provoke hemorrhagic transformation as AF... more
Background and Purpose: It is unknown when to start anticoagulation after acute ischemic stroke (AIS) from atrial fibrillation (AF). Early anticoagulation may prevent recurrent infarctions but may provoke hemorrhagic transformation as AF strokes are typically larger and hemorrhagic transformation-prone. Later anticoagulation may prevent hemorrhagic transformation but increases risk of secondary stroke in this time frame. Our aim was to compare early anticoagulation with apixaban in AF patients with stroke or transient ischemic attack (TIA) versus warfarin administration at later intervals. Methods: AREST (Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation) was an open-label, randomized controlled trial comparing the safety of early use of apixaban at day 0 to 3 for TIA, day 3 to 5 for small-sized AIS (<1.5 cm), and day 7 to 9 for medium-sized AIS (≥1.5 cm, excluding full cortical territory), to warfarin, in a 1:1 ratio at 1 week post-TIA, or ...
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In this paper, we propose a framework for accelerated reconstruction of 2D phase contrast magnetic resonance images from undersampled k-space domain by using deep learning methods. Undersampling in k-space violates Nyquist Sampling and... more
In this paper, we propose a framework for accelerated reconstruction of 2D phase contrast magnetic resonance images from undersampled k-space domain by using deep learning methods. Undersampling in k-space violates Nyquist Sampling and creates artifacts in the image domain. In the proposed method, we consider the reconstruction problem as a de-aliasing problem in complex spatial domain. To test the proposed method, from fully sampled k-space data undersampling in k-space was performed in the phase-encode direction based on a probability density function which ensures maximum rate of sampling in low frequency regions. For the deep convolutional neural network (CNN) we chose the U-net architecture. The proposed CNN was trained and tested on 4D flow MRI data in 14 subjects with aortic stenosis. The reconstructed complex two channel image showed that the U-net is able to unaliase the undersampled flow images with resulting magnitude and phase difference images showing good agreement with the fully sampled magnitude and phase images. We show that the proposed method outperforms 2D compressed sensing approach of spatial total variation regularization method. Flow waveforms derived from reconstructed images closely follow flow waveforms derived from the original data. Moreover, the method is computationally fast. Each 2D magnitude and phase image is reconstructed within a second using a single GPU.
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Introduction: Atrial fibrillation (AF) represents a cardiovascular syndrome which can lead to embolic stroke. Several AF clinical trials have shown a decrease risk of stroke with anticoagulation using warfarin. Currently, there are two... more
Introduction: Atrial fibrillation (AF) represents a cardiovascular syndrome which can lead to embolic stroke. Several AF clinical trials have shown a decrease risk of stroke with anticoagulation using warfarin. Currently, there are two approaches for anticoagulation in AF patients. For outpatients, warfarin is used with an INR goal 2.0–3.0. For inpatients requiring cardioversion, unfractionated heparin (UFH, IV) is used as a bridge to therapeutic warfarin. More recently, anticoagulation with a low molecular weight heparin, enoxaparin, has been reported to give a more predictable anticoagulant response than UFH in TEEguided cardioversion. The present study compares the markers of inflammation and thrombin generation in patients included in the ACUTE II study. Methods: This was a randomized multicenter trial of 155 patients from 17 clinical sites, the anticoagulant activity of LMWH (enoxaparin, 1 mg/kg sc bid, Sanofi-Aventis, n=76) was compared to that of UFH (APTT 1.5 – 2.5 x control...
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Three‐dimensional (3D) echocardiography is the most accurate echocardiographic method for ventricular chamber quantification. It is unclear how two‐dimensional (2D) techniques perform against 3D technology and whether 2D methods can be... more
Three‐dimensional (3D) echocardiography is the most accurate echocardiographic method for ventricular chamber quantification. It is unclear how two‐dimensional (2D) techniques perform against 3D technology and whether 2D methods can be extrapolated to obtain 3D data.
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This study assessed if frequent premature atrial contractions (PACs) were associated with decreased left atrial (LA) strain and adverse remodeling.
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Asian hypertrophic cardiomyopathy (AHCM) is a rare variant of hypertrophic cardiomyopathy (HCM) that is more prevalent in the Asian population. There is significant overlap between AHCM, mid‐cavitary obstruction, and apical aneurysms.... more
Asian hypertrophic cardiomyopathy (AHCM) is a rare variant of hypertrophic cardiomyopathy (HCM) that is more prevalent in the Asian population. There is significant overlap between AHCM, mid‐cavitary obstruction, and apical aneurysms. Although more benign compared to HCM, the course of AHCM is not clearly defined. We present an interesting case of an African American male with known AHCM who develops symptomatic mid‐cavitary obstruction and apical aneurysm 11 years after initial diagnosis.
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Apical variant hypertrophic cardiomyopathy (AHCM) is a rare genetic disease that causes thickening of the left ventricular apex (LVA). It is unclear how the myocardium restructures over time in individuals with AHCM. Here, we present a... more
Apical variant hypertrophic cardiomyopathy (AHCM) is a rare genetic disease that causes thickening of the left ventricular apex (LVA). It is unclear how the myocardium restructures over time in individuals with AHCM. Here, we present a patient with known AHCM whose myocardium evolved to develop mid-
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Dual-Venc flow acquisition sequences perform flow imaging with differing Vencs. The technique can be used to improve velocity to noise ratio and image quality for diastolic flow velocities as part of a single scan. In this paper,... more
Dual-Venc flow acquisition sequences perform flow imaging with differing Vencs. The technique can be used to improve velocity to noise ratio and image quality for diastolic flow velocities as part of a single scan. In this paper, Dual-Venc was used in conjunction with spiral read-out trajectories, offering a faster coverage of k-space. The results illustrate that 4D Dual Venc Spiral Flow behaves similarly to 4D Dual-Venc Cartesian Flow but with the benefit of faster acquisition time and lower echo time (TE).
The left atrial appendage (LAA) in the setting of non‐valvular atrial fibrillation (NVAF) is the predominant location for intracardiac thrombus formation. An absent LAA is a very rare congenital cardiac anomaly. We present a case of a... more
The left atrial appendage (LAA) in the setting of non‐valvular atrial fibrillation (NVAF) is the predominant location for intracardiac thrombus formation. An absent LAA is a very rare congenital cardiac anomaly. We present a case of a 79‐year‐old female with NVAF, high CHADS2VASC2 score, and high bleeding risk who presented for elective Watchman™ left atrial appendage closure device implant. A pre‐procedural transesophageal echocardiography showed an absent LAA. This finding was confirmed with cardiac computed tomography and a left atrial angiogram. The patient was discharged on medical therapy with close outpatient follow‐up.
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Patients with cancer can present with difficult management issues, as the medicine can sometimes cause sequelae destructive to healthy tissue. As this population lives longer, cardiotoxic effects are beginning to emerge, but the early... more
Patients with cancer can present with difficult management issues, as the medicine can sometimes cause sequelae destructive to healthy tissue. As this population lives longer, cardiotoxic effects are beginning to emerge, but the early recognition of this signal can prove difficult, with too late a recognition leading to lifelong cardiac impairment and dysfunction. Cardio-oncology can bridge this difficulty, and echocardiography and its newer imaging abilities are proving efficacious in this population. This article will address common sequelae of cardiotoxic treatment regimens and offer recommendations for echocardiographic surveillance. We recommend echocardiography, preferably three-dimensional and strain imaging, to monitor for cardiotoxic myocardial effects before, during, and after chemotherapy with cardiotoxic drug regimens, particularly anthracycline derivatives. A reduction in left ventricular (LV) global longitudinal strain in all patients, or reduction in LV global circumferential strain or global radial strain in patients at intermediate to high risk for cardiotoxicity, despite normal LV ejection fraction warrants a clinical assessment on the benefits of continuing cardiotoxic chemotherapeutic agents. Lifelong surveillance using echocardiography for cardiotoxicity and radiation-related valvular, pericardial, and coronary artery disease is prudent.
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Abstract 1317: Anticoagulant Responses in Patients Receiving Low Molecular Weight Heparin Compared to Unfractionated Heparin for Transesophageal Echocardiography Guided Cardioversion of Atrial Fibrillation: Results from the Assessment of Cardioversion Using Transesophageal Echocardiography Random...more
Research Interests: Medicine and Circulation
Background: Patients presenting with Cocaine associated chest pain are typically younger than patients with traditional risk factors but are at risk for accelerated Coronary artery disease. Radiation exposure associated with modes of... more
Background: Patients presenting with Cocaine associated chest pain are typically younger than patients with traditional risk factors but are at risk for accelerated Coronary artery disease. Radiation exposure associated with modes of stress testing such as Coronary CT or SPECT, makes it concerning especially in young females of childbearing age group presenting with cocaine associated chest pain. Stress echocardiography avoids radiation exposure, is more cost effective, saves time and adds to diagnostic information especially in patients with chest pain. However, safety of stress echocardiography has not been well studied in cocaine positive patients. Pharmacological testing with dobutamine raises concerns regarding provoking vasospasm or an exaggerated hypertensive response in these patients due to excessive sympathetic stimulation. Hypertensive response with stress testing can cause wall motion abnormalities without coronary disease and affect specificity of stress echocardiography. Methods: We conducted a retrospective analysis of patients who presented with chest pain and underwent stress echocardiography and had toxicology screen for cocaine positive during that visit. Cocaine positive patients were compared with age matched cocaine negative patients and assessed for hypertensive response, ischemic changes and complications during stress echocardiography. Results: No sustained arrhythmias, cardiac arrests or major complications occurred in both groups and overall safety in cocaine positive patients was similar to the control group both with treadmill and dobutamine stress echocardiography. Incidence of hypertensive response was not increased compared to controls with both exercise and dobutamine stress testing. Conclusion: Stress echocardiography appears to be a safe and useful procedure for risk stratification for cocaine associated chest pain patients once acute coronary syndrome is ruled out. ![Graphic][1] [1]: /embed/inline-graphic-1.gif
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Background: Chest pain is one of the most common reasons for Emergency Department (ED) visits and Chest pain centers (CPC) improve efficiency by triaging low and intermediate risk patients more effectively. We examined the Length of stay... more
Background: Chest pain is one of the most common reasons for Emergency Department (ED) visits and Chest pain centers (CPC) improve efficiency by triaging low and intermediate risk patients more effectively. We examined the Length of stay (LOS) in CPC and the utility of stress testing and further risk stratification during the CPC visit using a Bayesian analysis. Based on this analysis we suggest some performance improvement measures which may reduce costs and improve efficiency. Methods: We conducted a retrospective analysis of patients evaluated in our CPC in 2011. For each patient the pre and post stress test conditional probability of coronary artery disease (CAD) was calculated using Bayes Theorem. Based on the estimated pretest probability, patients were classified into low, intermediate and high risk groups. The post stress testing conditional probabilities were calculated and used to determine if results of stress testing had a significant impact on further cardiovascular risk assessment. Results: 95% of patients tested were negative for ischemia and were not admitted, reducing length of stay in ED. Stress echocardiography was the most utilized modality of stress testing, which provided additional diagnoses such as valvular heart disease in 2% of patients while avoiding radiation exposure. A Bayesian analysis indicated that in the low (pre-test) probability group consisting of young females with atypical symptoms remained in the low probability group irrespective of stress testing results. Also most intermediate risk patients remained in the intermediate risk category despite negative testing. Conclusions: CPC has improved cost-effectiveness due to reduced length of stay in ED, avoiding inpatient admissions and thereby reducing costs. As highlighted by the Bayesian analysis that most intermediate risk patients remained in the intermediate risk category despite negative testing, the need for pre-discharge testing needs to be re-examined as negative stress tests do not eliminate risk of CAD and avoiding these test can help further reduce costs and improve efficiency. Once acute coronary syndrome is ruled out, CPC visits should be more centered on establishing a primary care physician, risk factor modification, smoking cessation and promoting primary prevention. ![Graphic][1] [1]: /embed/inline-graphic-1.gif
Cardio-embolic phenomenon is believed to underlie a significant proportion of cryptogenic strokes. We recently showed that intrapulmonary shunt (IPS) was associated with cryptogenic stroke and transient ischemic attack (TIA). We... more
Cardio-embolic phenomenon is believed to underlie a significant proportion of cryptogenic strokes. We recently showed that intrapulmonary shunt (IPS) was associated with cryptogenic stroke and transient ischemic attack (TIA). We hypothesized that patients with prior cryptogenic stroke or TIA that had an IPS were at a higher risk for recurrent ischemic events. The population included subjects with cryptogenic cerebrovascular accident (CVA) or TIA. Inclusion criteria were age ≥18 years, sinus rhythm, and clinically indicated transesophageal echocardiography (TEE). Exclusion criteria were hemorrhagic CVA, septal defect, and patent foramen. Patients were followed from index TEE. Of 71 patients, 8 were lost to follow-up. A total of 23 patients had and 40 were without IPS. Average follow-up duration was 38.3 ± 19.2 months. Groups were similar at baseline. There was no significant difference in the recurrence of ischemic CVA or TIA in the IPS versus non-IPS groups (0% vs. 7.5%; P = NS). There was no difference between the incidence of hemorrhagic CVA in the IPS and non-IPS groups (4.3% vs. 5.0%; P = NS). The proportion of patients on warfarin in the IPS group was significantly higher compared to the non-IPS group (17.4% vs. 0%; P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). Patients with IPS and cryptogenic stroke or TIA did not have a higher recurrence of ischemic cerebral events. Warfarin was significantly higher at follow-up in the IPS compared to the non-IPS group, which may explain these findings. A study randomizing patients with IPS and cryptogenic stroke or TIA to warfarin or no warfarin would be of great interest.
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A cardiac phantom can be of crucial importance in the development and validation of ultrasound and cardiac magnetic resonance (MR) imaging and image analysis methods. A biventricular multimodal cardiac phantom has been manufactured... more
A cardiac phantom can be of crucial importance in the development and validation of ultrasound and cardiac magnetic resonance (MR) imaging and image analysis methods. A biventricular multimodal cardiac phantom has been manufactured in-house that can simulate normal and pathologic hearts with different degrees of infarction. The two-chamber structure can simulate the asymmetric left ventricular motion. Poly Vinyl Alcohol (PVA) is utilized as the basic material since it can simulate the shape, elasticity, and MR and ultrasound properties of the heart. The cardiac shape is simulated using a two-chamber acrylic mold. An additional pathologic heart phantom has been built to simulate aneurysm and infarction. Segmental dyskinesis is modeled based on three inclusions of different shapes and different degrees of elasticity. The cardiac elasticity is adjusted based on freeze-thaw cycles of the PVA cryogel for normal and scarred regions.
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Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in... more
Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined. In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area. We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry...
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The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on TDI (Tissue Doppler Imaging) or... more
The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on TDI (Tissue Doppler Imaging) or speckle tracking. These methods are based on two techniques which to a large degree are independent—the Doppler phenomenon and image sequence processing, respectively. Herein, to increase the accuracy of the speckle tracking technique and to cope with the angle dependency of TDI, a combined approach dubbed TDIOF (Tissue Doppler Imaging Optical Flow) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms minimized using algebraic equations and is validated on simulated images, a physical heart phantom, and in-vivo data. It was observed that the additional Doppler term is able to increase the accuracy of speckle tracking, compared to two popular motion estimation and speckle tracking techniques (Horn-Schunck and block matching methods). This observation was more pronounced when noise was present. . The magnitude and angular error for TDIOF applied to simulated images when comparing estimated motion with ground-truth motion were 15 % and 9.2 degrees/frame, respectively. The magnitude and angular error for images acquired from physical phantoms were 22 % and 15.2 degrees/frame, respectively. As an additional validation, echocardiography-derived strains were compared to tagged MRI-derived myocardial strains in the same subjects. The correlation coefficient (r) between the TDIOF-derived radial strains and tagged MRI-derived radial strains value were 0.83 (\(\mathrm{P}<0.001\) ). The correlation coefficient (r) for the TDIOF-derived circumferential strains compared to the tagged MRI-derived circumferential strains were 0.86 (\(\mathrm{P}<0.001\) ). The comparison of TDIOF-derived and block matching speckle tracking and Horn-Schunck optical flow strain values using student t-test demonstrated superiority of TDIOF (95 % confidence interval, \(\mathrm{P}<0.001\) ).
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In this paper, we combine a ventricular kinematic model and an ultrasound simulation model in order to simulate the echocardiographic imaging process. In addition to its capability to generate raw RF data, when compared to previous... more
In this paper, we combine a ventricular kinematic model and an ultrasound simulation model in order to simulate the echocardiographic imaging process. In addition to its capability to generate raw RF data, when compared to previous echocardiography simulation models, the result achieves more realistic B-Mode images. Several echocardiography parameters were taken into account including central frequency, apodization, number of elements
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ABSTRACT Quantitative motion analysis of echocardiographic images helps clinicians with the diagnosis and therapy of patients suffering from cardiac disease. Quantitative analysis is usually based on TDI (Tissue Doppler Imaging) or... more
ABSTRACT Quantitative motion analysis of echocardiographic images helps clinicians with the diagnosis and therapy of patients suffering from cardiac disease. Quantitative analysis is usually based on TDI (Tissue Doppler Imaging) or speckle tracking. These methods are based on two independent techniques - the Doppler Effect and image registration, respectively. In order to increase the accuracy of the speckle tracking technique and cope with the angle dependency of TDI, herein, a combined approach dubbed TDIOF (Tissue Doppler Imaging Optical Flow) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms in an optical flow framework and minimized using algebraic equations. In this paper, we report on validations with simulated, physical cardiac phantom, and in-vivo patient data. It is shown that the additional Doppler term is able to increase the accuracy of speckle tracking, the basis for several commercially available echocardiography analysis techniques.
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ABSTRACT A dynamic cardiac phantom can play a significant role in the evaluation and development of ultrasound and cardiac magnetic resonance (MR) motion tracking and registration methods. A four chamber multimodal cardiac phantom has... more
ABSTRACT A dynamic cardiac phantom can play a significant role in the evaluation and development of ultrasound and cardiac magnetic resonance (MR) motion tracking and registration methods. A four chamber multimodal cardiac phantom has been designed and built to simulate normal and pathologic hearts with different degrees of &quot;infarction&quot; and &quot;scar tissues&quot;. In this set up, cardiac valves have been designed and modeled as well. The four-chamber structure can simulate the asymmetric ventricular, atrial and valve motions. Poly Vinyl Alcohol (PVA) is used as the principal material since it can simulate the shape, elasticity, and MR and ultrasound properties of the heart. The cardiac shape is simulated using a four-chamber mold made of polymer clay. An additional pathologic heart phantom containing stiff inclusions has been manufactured in order to simulate an infracted heart. The stiff inclusions are of different shapes and different degrees of elasticity and are able to simulate abnormal cardiac segments. The cardiac elasticity is adjusted based on freeze-thaw cycles of the PVA cryogel for normal and scarred regions. Ultrasound and MRI markers were inserted in the cardiac phantom as landmarks for validations. To the best of our knowledge, this is the first multimodal phantom that models a dynamic four-chamber human heart including the cardiac valve.
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... Primary Malignant Cardiac Tumors: Update 1992 Charles R. Thomas, Jr., MD, George W. Johnson, jr., MD, Marcus F. Stoddard, MD, and Sonja Clifford, MD Key words: cardiac, primary, heart, malignant, mediastinal, sarcoma CLINICAL SUMMARY... more
... Primary Malignant Cardiac Tumors: Update 1992 Charles R. Thomas, Jr., MD, George W. Johnson, jr., MD, Marcus F. Stoddard, MD, and Sonja Clifford, MD Key words: cardiac, primary, heart, malignant, mediastinal, sarcoma CLINICAL SUMMARY ...
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ABSTRACT
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Inaccuracy of conventional four-dimensional (4D) flow MR imaging in the presence of random unsteady and turbulent blood flow distal to a narrowing has been an important challenge. Previous investigations have revealed that shorter echo... more
Inaccuracy of conventional four-dimensional (4D) flow MR imaging in the presence of random unsteady and turbulent blood flow distal to a narrowing has been an important challenge. Previous investigations have revealed that shorter echo times (TE) decrease the errors, leading to more accurate flow assessments. In this study, as part of a 4D flow acquisition, an Ultra-Short TE (UTE) method was adopted. UTE works based on a center-out radial k-space trajectory that inherently has a short TE. By employing free induction decay sampling starting from read-out gradient ramp-up, and by combining the refocusing lobe of the slice select gradient with the bipolar flow encoding gradient, TEs of ≈1 msec may be achieved. Both steady and pulsatile flow regimes, and in each case a range of Reynolds numbers, were studied in an in-vitro model. Flow assessment at low and medium flow rates demonstrated a good agreement between 4D UTE and conventional 4D flow techniques. However, 4D UTE flow significantly outperformed conventional 4D flow, at high flow rates for both steady and pulsatile flow regimes. Feasibility of the method in one patient with Aortic Stenosis was also demonstrated. For both steady and pulsatile high flow rates, the measured flow distal to the stenotic narrowing using conventional 4D flow revealed more than 20% error compared to the ground-truth flow. This error was reduced to less than 5% using the 4D UTE flow technique. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.