Toward 3-D Echocardiographic Determination of Regional Myofiber Structure

Milne, Michelle L.; Singh, Gautam K.; Miller, James G.; Wallace, Kirk; Holland, Mark

doi:10.1016/j.ultrasmedbio.2015.09.024

Cited by 7 publications

(11 citation statements)

References 35 publications

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“…Previously, we validated that apparent ultrasonic backscatter could be used to map myofiber architecture in human-size sheep hearts using a clinical imaging system (Milne, et al 2016). The increase in pre-clinical studies, including a number of rat models of heart failure, suggest numerous opportunities to apply this method in rodents.…”

Section: Discussionmentioning

confidence: 99%

“…Mean and standard deviation of each of the seven hearts were calculated for each data acquisition mode. Previous work indicated that the relationship between apparent backscatter and fiber angle may be empirically modeled by a function of even powers of sines and cosines (Milne, et al 2012, Milne, et al 2016, Mottley and Miller 1988). Based on these works and our fits of individual and mean data, the mean data was fit to the following function: …”

Section: Methodsmentioning

confidence: 99%

“…Previously, the fiber orientation (angle of the fiber relative to the direction of insonification) of human-sized sheep heart was determined using ultrasound and validated using DTI (Milne, et al 2012, Milne, et al 2016). The method utilizes a change in apparent ultrasonic backscatter that is dependent on the orientation of myofibers.…”

Section: Introductionmentioning

confidence: 99%

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Myocardial Fiber Mapping of Rat Hearts, Using Apparent Backscatter, with Histologic Validation

Milne

Schick

Alkhazal

et al. 2019

Ultrasound in Medicine & Biology

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Myocardial fiber architecture is a physiologically important regulator of ejection fraction, strain, and pressure development. Apparent ultrasonic backscatter has been shown to be a useful method for recreating the myocardial fiber architecture in human-sized sheep hearts, due to the dependence of its amplitude on the relative orientation of a myofiber to the angle of ultrasonic insonification. Thus, the anisotropy of the backscatter signal is linked to, and provides information about, the fiber orientation. In this study, we sought to determine if apparent backscatter could be used to measure myofiber orientation in rodent hearts. Fixed adult rat hearts were imaged intact, and both a transmural cylindrical core and transmural wedge of the LV free wall were imaged. Cylindrical core samples confirmed that backscatter anisotropy could be measured in rat hearts. Ultrasound and histological analysis of transmural myocardial wedge samples confirmed that the apparent backscatter could be reproducibly mapped to fiber orientation (angle of the fiber relative to the direction of insonification). These data provided a quantitative relationship between the apparent backscatter and fiber angle that was applied to whole heart images. Myocardial fiber architecture was successfully measured in rat hearts. Quantifying myocardial fiber architecture using apparent backscatter provides a number of advantages, including its scalable use from rodents to man, its rapid low-cost acquisition, and minimal contraindications. The method outlined in this study provides a method for investigators to begin detailed assessments of how the myocardial fiber architecture changes in pre-clinical disease models, which can be immediately translated into the clinic.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Myocardial Fiber Mapping of Rat Hearts, Using Apparent Backscatter, with Histologic Validation

Milne

Schick

Alkhazal

et al. 2019

Ultrasound in Medicine & Biology

Self Cite

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“…We hypothesize that measuring myofiber-direct strain, as opposed to principal ventricular axis strains, might help design mechanical experiments that would better mimic physiologic myofiber strains and strain rates, including in the context of increased fibrosis common in diastolic dysfunction [30,34]. Myofiber strain is more complicated to measure because MRI or ultrasound techniques must be used to first measure the helical myofiber architecture [10,55,56]. These measures might validate predictions from ex vivo studies.…”

Section: A Translational Perspective On Myocardial Motionmentioning

confidence: 99%

How myofilament strain and strain rate lead the dance of the cardiac cycle

Chung

2019

Archives of Biochemistry and Biophysics

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Movement of the myocardium can modify organ-level cardiac function and its molecular (crossbridge) mechanisms. This motion, which is defined by myocardial strain and strain rate (muscle shortening, lengthening, and the speed of these movements), occurs throughout the cardiac cycle, including during isovolumic periods. This review highlights how the left ventricular myocardium moves throughout the cardiac cycle, how muscle mechanics experiments provide insight into the regulation of forces used to move blood in and out of the left ventricle, and its impact on (and regulation by) crossbridge and sarcomere kinetics. We specifically highlight how muscle mechanics experiments explain how myocardial relaxation is accelerated by lengthening (strain rate) during late systole and isovolumic relaxation, a lengthening which has been measured in human hearts. Advancing and refining both in vivo measurement and ex vivo protocols with physiologic strain and strain rates could reveal important insights into molecular (crossbridge) kinetics. These advances could provide an improvement in both diagnosis and precise treatment of cardiac dysfunction.

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“…Registration errors also contribute to angle discrepancies. In sheep hearts, the average angle difference between two scans of the same heart was found to vary by nearly 10 degrees, mostly due to registration error [2]. Acute angle error (AAE) has been used as a common approach to quantify angle differences.…”

Section: Introductionmentioning

confidence: 99%

A new method to quantify fiber orientation similarity in registered volumes

Dormer

Jiang

Wagner

et al. 2017

Medical Imaging 2017: Image Perception, Observer Performance, and Technology Assessment

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Differences in fiber orientations between registered image volumes can be difficult to quantify. Angular errors between diffusion tensor imaging (DTI) volumes are often a combination of image registration errors and fluctuations of diffusion values that are used to determine the fiber orientations. In order to properly quantify the similarity between two images containing fiber orientation information, both displacement and angular fluctuation should be considered. We present a method to quantify fiber orientation similarity between registered images by allowing small pixel displacements in conjunction with minor angle differences. Adjustments to the allowed pixel displacement and degree of angle difference can help identify the major factor contributing to the error of fiber angles. The proposed method can provide a new metric for the evaluation of the fiber orientation difference.

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Toward 3-D Echocardiographic Determination of Regional Myofiber Structure

Cited by 7 publications

References 35 publications

Myocardial Fiber Mapping of Rat Hearts, Using Apparent Backscatter, with Histologic Validation

Myocardial Fiber Mapping of Rat Hearts, Using Apparent Backscatter, with Histologic Validation

How myofilament strain and strain rate lead the dance of the cardiac cycle

A new method to quantify fiber orientation similarity in registered volumes

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