Anisotropy of the ultrasonic backscatter of myocardial tissue: I. Theory and measurements i
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Mottley, Jack G.; Miller, James G.

doi:10.1121/1.396118

Cited by 146 publications

(63 citation statements)

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“…Analysis of its dynamic aspects (cycledependent variation of IBS) is useful to obtain information about myocardial intrinsic contractile performance, independent of wall motion. 6,7 Furthermore, myocardial reflectivity (IBS) in humans is directly related to myocardium collagen content. 8 The aim of the study was to assess diagnostic and prognostic values of integrated backscatter indexes in patients with severe AS and in particular to test if these textural indexes could have a real incremental value in comparison to conventional echocardiographic systolic and diastolic functional indexes in decision-making of this valvular pathology.…”

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confidence: 99%

Severe Aortic Stenosis and Myocardial Function

et al. 2004

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Background— The aim of this study was to assess the myocardial reflectivity pattern in severe aortic valve stenosis through the use of integrated backscatter (IBS) analysis. Patients with aortic stenosis (AS) were carefully selected in the Department of Cardiology. Methods and Results— Thirty-five subjects (AS: valve orifice ≤1 cm 2 ; 12 female; mean age, 71.8±6.2 years) and 25 healthy subjects were studied. All subjects of the study had conventional 2D-Doppler echocardiography and IBS. Backscatter signal was sampled at the septum and posterior wall levels. Patients with AS were divided into 2 groups: 16 patients with initial signs of congestive heart failure and a depressed left ventricular systolic function (DSF) (ejection fraction [EF] range, 35% to 50%) and 19 asymptomatic patients with normal left ventricular systolic function (NSF) (EF >50%). Myocardial echo intensity (pericardium related) was significantly higher at the septum and posterior wall levels in DSF than in NSF and in control subjects. IBS variation, as an expression of variation of the signal, appeared to be significantly lower in AS with DSF than in NSF and in control subjects, at both the septum and posterior wall levels. Patients with DSF underwent aortic valve replacement, and, during surgical intervention, a septal myocardial biopsy was made for evaluation of myocardium/fibrosis ratio. Abnormally increased echo intensity was detected in left ventricular pressure overload by severe aortic stenosis and correlated with increase of myocardial collagen content (operating biopsy). Conclusions— One year after aortic valve replacement, we observed a significant reduction of left ventricular mass, and, only if pericardial indexed IBS value (reduction of interstitial fibrosis) decreased, it was possible to observe an improvement of EF and of IBS variation.

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confidence: 99%

Severe Aortic Stenosis and Myocardial Function

et al. 2004

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“…Observações similares quanto à influência do conteúdo de água tissular sobre o coeficiente de backscatter foram feitas para outros modelos patológicos 18 . Do mesmo modo, o aumento do conteúdo de colágeno presente no processo de fibrose comum a vários processos patológicos cardiovasculares poderia implicar em maior intensidade do integrated backscatter 19,20 . Isto têm sido observado em vários estudos 18,21,22 .…”

Section: O Integrated Backscatterunclassified

“…Esta hipótese encontra alicerce nas evidências de que a intensidade do integrated backscatter é dependente da orientação do feixe de ultra-som em relação à orientação das fibras do tecido estudado 20,26 .…”

Section: O Integrated Backscatterunclassified

Caracterização ultra-sônica tecidual miocárdica

Pazin‐Filho¹,

Schmidt

Almeida-Filho

et al. 2003

Arq. Bras. Cardiol.

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Atualização cardite, isquemia e trauma, como causa de mobilidade parietal segmentar anormal); 3) quantificar a extensão da mudança ou envolvimento; e 4) diferenciar tecido normal, embora não funcionante de tecido lesado ou necrótico 4 .A perspectiva concreta de utilização da ecocardiografia na análise das características anatômicas ultra-estruturais do músculo cardíaco abriu-se durante a última década, com a técnica da caracterização tecidual, que avalia, quantitativamente, as alterações nas ondas de ultra-som durante sua interação física com o tecido miocárdico, permitindo estabelecer correlações com as propriedades físicas das estruturas do tecido miocárdico 4 .Quando o feixe de ultra-som, emitido pelo transdutor, incide sobre os tecidos, basicamente dois tipos de sinais refletidos retornam ao transdutor. Eles são diretamente dependentes da relação entre a dimensão da superfície atingida pelo feixe de ultra-som e o comprimento de onda desse feixe 5 ( fig. 1). Assim, existe um primeiro conjunto de sinais decorrentes do fenômeno de reflexão especular do ultrasom, incidindo sobre superfícies que apresentam dimensão muito maior que o comprimento de onda do ultra-som; mas também existe um outro, decorrente do fenômeno de dispersão (em inglês, scatter), ocorrido quando a dimensão da superfície sobre a qual incide o feixe de ultra-som é muito menor que o seu comprimento de onda. Ao contrário do fenômeno de reflexão, que se dá preferencialmente em uma direção, o fenômeno de dispersão é multidirecional e apenas uma parte pequena do ultra-som dispersado pode ser captada pelo transdutor (conhecido como backscatter). O fenô-meno de dispersão é o responsável pela produção dos sinais que são processados para análise de velocidade e direção de fluxo sanguíneo (técnica de Doppler), ao mesmo tempo que depende da heterogeneidade regional das propriedades físicas do tecido, especialmente de densidade e compressibilidade, quando interage com o ultra-som, além da extensão e distribuição dessa heterogeneidade 5 .Para a obtenção das imagens ecocardiográficas bidimensionais convencionais, são utilizados os sinais oriundos da reflexão especular, que permitem imagens de melhor resolução espacial, enquanto os sinais provenientes do Ao longo das últimas décadas, os métodos ultrasonográficos de investigação cardiovascular receberam avanços tecnológicos, contribuindo decisivamente para o aprimoramento diagnóstico e prognóstico de doenças, que apresentam envolvimento cardíaco. Não obstante ter a ecocardiografia se consolidado como método de ampla utilização clínica, em face do amplo conjunto de informações morfológicas e funcionais que essa técnica pode proporcionar, os avanços relativos à sua capacidade de permitir inferên-cias relativas à constituição anatômica de estruturas cardía-cas eram, até recentemente, bastante limitados.Desde o início do desenvolvimento da ecocardiografia, era possível documentar que algumas estruturas eram mais refringentes do que outras, o que, em muitas ocasiões, podia ser correlacionado com a constituição da e...

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“…24 For example, Miller and coworkers thoroughly investigated the relationship between myocardial anisotropy and echocardiography intensities. [25][26][27][28][29][30][31] These studies indicate that the anisotropic intensities mainly relate to the variable cardiac fiber orientations: the orientations that are parallel to the ultrasound beams lead to the lowest intensities and those that are perpendicular to the beam lead to the highest intensities, as shown in Figs. 1(b) and 1(c).…”

Section: Introductionmentioning

confidence: 99%

“…Next, the tensors of DTI data were decomposed into three eigenvectors, and cardiac fiber orientations were tracked by a determinative method of fractional anisotropy. 26,27,35,36 Since different ultrasound imaging directions lead to different segmental intensities, prior to the simulation, the architectures of rat hearts acquired from MRI were first registered to the corresponding real ultrasound volume. There are two steps for the registration: (1) registration between structural MRI geometries and the real ultrasound ones using a rigid transformation based on the location of the apex and papillary muscles 37 and (2) relocation and reorientation of DTI-derived fiber orientations using the rigid transformation.…”

Section: A4 Data Preprocessingmentioning

confidence: 99%

Simulating cardiac ultrasound image based on MR diffusion tensor imaging

et al. 2015

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Purpose: Cardiac ultrasound simulation can have important applications in the design of ultrasound systems, understanding the interaction effect between ultrasound and tissue and setting the ground truth for validating quantification methods. Current ultrasound simulation methods fail to simulate the myocardial intensity anisotropies. New simulation methods are needed in order to simulate realistic ultrasound images of the heart. Methods: The proposed cardiac ultrasound image simulation method is based on diffusion tensor imaging (DTI) data of the heart. The method utilizes both the cardiac geometry and the fiber orientation information to simulate the anisotropic intensities in B-mode ultrasound images. Before the simulation procedure, the geometry and fiber orientations of the heart are obtained from high-resolution structural MRI and DTI data, respectively. The simulation includes two important steps. First, the backscatter coefficients of the point scatterers inside the myocardium are processed according to the fiber orientations using an anisotropic model. Second, the cardiac ultrasound images are simulated with anisotropic myocardial intensities. The proposed method was also compared with two other nonanisotropic intensity methods using 50 B-mode ultrasound image volumes of five different rat hearts. The simulated images were also compared with the ultrasound images of a diseased rat heart in vivo. A new segmental evaluation method is proposed to validate the simulation results. The average relative errors (AREs) of five parameters, i.e., mean intensity, Rayleigh distribution parameter σ, and first, second, and third quartiles, were utilized as the evaluation metrics. The simulated images were quantitatively compared with real ultrasound images in both ex vivo and in vivo experiments. Results: The proposed ultrasound image simulation method can realistically simulate cardiac ultrasound images of the heart using high-resolution MR-DTI data. The AREs of their proposed method are 19% for the mean intensity, 17.7% for the scale parameter of Rayleigh distribution, 36.8% for the first quartile of the image intensities, 25.2% for the second quartile, and 19.9% for the third quartile. In contrast, the errors of the other two methods are generally five times more than those of their proposed method. Conclusions: The proposed simulation method uses MR-DTI data and realistically generates cardiac ultrasound images with anisotropic intensities inside the myocardium. The ultrasound simulation method could provide a tool for many potential research and clinical applications in cardiac ultrasound imaging. C 2015 American Association of Physicists in Medicine.

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Anisotropy of the ultrasonic backscatter of myocardial tissue: I. Theory and measurements i n v i t r o

Cited by 146 publications

References 0 publications

Severe Aortic Stenosis and Myocardial Function

Severe Aortic Stenosis and Myocardial Function

Caracterização ultra-sônica tecidual miocárdica

Simulating cardiac ultrasound image based on MR diffusion tensor imaging

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