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Integrated MRI assessment of regional function and perfusion in canine myocardial infarction

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A single integrated examination using regional measurements of perfusion from contrast-enhanced MRI and three-dimensional (3D) strain from tissue-tagged MRI was developed to differentiate infarcted myocardium from adjacent tissue with functional abnormalities. Ten dogs were studied at baseline and 10 days after a 2-hour occlusion of the left anterior descending coronary artery (LAD). Strain was determined using a 3D finite element model. Two-dimensional measurements of hypoenhancing regions were highly correlated with myocardial viability (r = 0.96).

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Automated Regional Wall Motion Abnormality Detection by Combining Rest and Stress Cardiac MRI: Correlation With Contrast-Enhanced MRI

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Purpose:
To correlate an automated regional wall motion abnormality (RWMA) detection method based on combined rest and dobutamine-stress cardiac MRI with the assessment of myocardial infarction from contrast-enhanced MRI (CE-MRI), and to demonstrate that adding stress data improves the detection of scar segments compared with rest data alone. Materials and Methods:
An automated RWMA detection method was built based on a statistical model of normokinetic myocardium from 41 healthy volunteers. The method was adapted to detect changes in RWMA from rest to stress.

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Aging alters patterns of regional nonuniformity in LV strain relaxation: a 3-D MR tissue tagging study

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Although age-related impairment of diastolic function is well documented, patterns of regional tissue relaxation impairment with age have not been characterized. MRI tissue tagging with a regional three-dimensional (3-D) analysis was performed in 15 younger (age 19–26 yr) and 16 older (age 60–74 yr) normal, healthy volunteers. The peak rate of relaxation of circumferential strain (RC) was decreased in the older group (on average, 105 ± 28 vs. 163 ± 18 %/s for older vs.

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Investigating Heart Failure Using Ventricular Imaging and Modelling

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It is well-established that ventricular hypertrophy is a transitional phase through the development of heart failure. A hypertrophic heart can remodel to compensate the loss of pump function, but it eventually becomes incapable of working efficiently, leading to heart failure. Many heart failure patients have preserved pump function (e.g. normal ejection fraction), but increased LV wall thickness and sometimes increased LV mass, which can mask a decrease in contractility.

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Estimation of epicardial strain using the motions of coronary bifurcations in biplane cinéangiography.

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A quantitative method for estimating epicardial deformation from the motion of the superficial coronary arteries is described. A structural model of the time-varying surface is constructed using tensor product basis functions which are bicubic Hermite in the spatial domain and sinusoidal in the temporal domain. The locii of the superficial coronary arteries are reconstructed interactively at diastasis and the bifurcations are tracked semiautomatically throughout as cardiac cycle.

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Left ventricular mass and volume: Fast calculation with guide-point modeling on MR images

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The authors describe a fast method for calculating left ventricle (LV) mass and volumes from multiplanar magnetic resonance (MR) images. Mathematic models were fitted to a small number of user-selected guide points in 15 healthy volunteers, 13 patients after myocardial infarction, and a canine model of mitral regurgitation in eight dogs. Errors between model and manual contours were small (LV mass, 1.8 g +/- 4.9 [mean +/- SD]; end-diastolic volume, 2.2 mL +/- 4.6; end-systolic volume, 2.3 mL +/- 3.8).

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Age-related changes in myocardial relaxation using three-dimensional tagged magnetic resonance imaging

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Purpose. Marked changes in left ventricular diastolic filling occur with advancing age, but alterations in myocardial movement accompanying these findings have not been previously documented. We aimed to identify differences in myocardial motion during relaxation and diastole using magnetic resonance imaging (MRI), with tagging, which uniquely allows accurate, noninvasive assessment of myocardial movement in three dimensions. Methods.

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In-line Automated Tracking for Ventricular Function With Magnetic Resonance Imaging

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An efficient nonrigid registration algorithm was implemented on the image reconstruction computer to enable in-line automatic tracking of features in steady-state free precession cine images. Four-dimensional left ventricle function analysis was performed with and without use of the in-line automatic tracking result. The method was tested in 30 patients referred for cardiac magnetic resonance imaging for a variety of clinical assessments.

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Deformable models with parameter functions for cardiac motion analysis from tagged MRI data

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We present a new method for analyzing the motion of the heart's left ventricle (LV) from tagged magnetic resonance imaging (MRI) data. Our technique is based on the development of a new class of physics-based deformable models whose parameters are functions. They allow the definition of new parameterized primitives and parameterized deformations which can capture the local shape variation of a complex object. Furthermore, these parameters are intuitive and require no complex post-processing in order to be used by a physician.

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Effects of excessive long-term exercise on cardiac function and myocyte remodeling in hypertensive heart failure rats

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The long-term effects of exercise on cardiac function and myocyte remodeling in hypertension/progression of heart failure are poorly understood. We investigated whether exercise can attenuate pathological remodeling under hypertensive conditions. Fifteen female Spontaneously Hypertensive Heart Failure rats and 10 control rats were housed with running wheels beginning at 6 months of age. At 22 months of age, heart function of the trained rats was compared with heart function of age-matched sedentary hypertensive and control rats.

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