Segmentation of the Aortic Valve Apparatus in 3D Echocardiographic Images: Deformable Modeling of a Branching Medial Structure

Pouch, Alison M.; Tian, Sijie; Takabe, Manabu; Wang, Hongzhi; Yuan, Jie; Cheung, Albert T.; Jackson, Benjamin M.; Gorman, Joseph H.; Gorman, Robert C.; Yushkevich, Paul A.

doi:10.1007/978-3-319-14678-2_20

Cited by 8 publications

(9 citation statements)

References 10 publications

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“…For the former, we note that it has been extensively validated and known to produce accurate results when compared to the manual segmentation (Jassar et al, 2014; Pouch et al, 2015b; Pouch et al, 2013; Witschey et al, 2014). For the later, we have extensively validated the method against gold-standard in-vitro data with accuracies to ±0.2 mm (Aggarwal et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

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In-vivo heterogeneous functional and residual strains in human aortic valve leaflets

Aggarwal

Pouch

Lai

et al. 2016

Journal of Biomechanics

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Residual and physiological functional strains in soft tissues are known to play an important role in modulating organ stress distributions. Yet, no known comprehensive information on residual strains exist, or non-invasive techniques to quantify in-vivo deformations for the aortic valve (AV) leaflets. Herein we present a completely non-invasive approach for determining heterogeneous strains – both functional and residual – in semilunar valves and apply it to normal human AV leaflets. Transesophageal 3D echocardiographic (3DE) images of the AV were acquired from open-heart transplant patients, with each AV leaflet excised after heart explant and then imaged in a flattened configuration ex-vivo. Using an established spline parameterization of both 3DE segmentations and digitized ex-vivo images (Aggarwal et al., 2014), surface strains were calculated for deformation between the ex-vivo and three in-vivo configurations: fully open, just-coapted, and fully-loaded. Results indicated that leaflet area increased by an average of 20% from the ex-vivo to in-vivo open states, with a highly heterogeneous strain field. The increase in area from open to just-coapted state was the highest at an average of 25%, while that from just-coapted to fully-loaded remained almost unaltered. Going from the ex-vivo to in-vivo mid-systole configurations, the leaflet area near the basal attachment shrank slightly, whereas the free edge expanded by ~10%. This was accompanied by a 10° −20° shear along the circumferential-radial direction. Moreover, the principal stretches aligned approximately with the circumferential and radial directions for all cases, with the highest stretch being along the radial direction. Collectively, these results indicated that even though the AV did not support any measurable pressure gradient in the just-coapted state, the leaflets were significantly pre-strained with respect to the excised state. Furthermore, the collagen fibers of the leaflet were almost fully recruited in the just-coapted state, making the leaflet very stiff with marginal deformation under full pressure. Lastly, the deformation was always higher in the radial direction and lower along the circumferential one, the latter direction made stiffer by the preferential alignment of collagen fibers. These results provide significant insight into the distribution of residual strains and the in-vivo strains encountered during valve opening and closing in AV leaflets, and will form an important component of the tool that can evaluate valve's functional properties in a non-invasive manner.

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Section: Discussionmentioning

confidence: 99%

“…For each subject, segmentation of the AV apparatus was performed firstly in the open state (systole) using a multi-atlas segmentation and deformable modeling technique described in Pouch et al (2015b). Although different cusps were excised from each heart, segmentation of the entire AV apparatus was performed for all subjects.…”

Section: Methodsmentioning

confidence: 99%

In-vivo heterogeneous functional and residual strains in human aortic valve leaflets

Aggarwal

Pouch

Lai

et al. 2016

Journal of Biomechanics

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“…With the objective of avoiding the need for excision, inverse modeling approaches have been employed to determine accurately and reliably the mechanical properties of valve leaflets. Recent advancements in 3D ultrasound technology provide the opportunity to obtain patient specific valve images in vivo , 155 specifically the shape of the leaflets as they are loaded during the closing phase without the need to include physical markers that severely hamper the clinical applicability of the inversemodeling approach—these methods are certainly the only resort to characterize native leaflets non-invasively in vivo , but their direct translation to monitor the performance of BHVs over their service life could yield important data to improve insight on failure mechanisms and possibly aid the design of more durable heterograft tissues and better BHVs.…”

Section: Computational Simulationsmentioning

confidence: 99%

Biomechanical Behavior of Bioprosthetic Heart Valve Heterograft Tissues: Characterization, Simulation, and Performance

Soares

Feaver

Zhang

et al. 2016

Cardiovasc Eng Tech

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The use of replacement heart valves continues to grow due to the increased prevalence of valvular heart disease resulting from an ageing population. Since bioprosthetic heart valves (BHVs) continue to be the preferred replacement valve, there continues to be a strong need to develop better and more reliable BHVs through and improved the general understanding of BHV failure mechanisms. The major technological hurdle for the lifespan of the BHV implant continues to be the durability of the constituent leaflet biomaterials, which if improved can lead to substantial clinical impact. In order to develop improved solutions for BHV biomaterials, it is critical to have a better understanding of the inherent biomechanical behaviors of the leaflet biomaterials, including chemical treatment technologies, the impact of repetitive mechanical loading, and the inherent failure modes. This review seeks to provide a comprehensive overview of these issues, with a focus on developing insight on the mechanisms of BHV function and failure. Additionally, this review provides a detailed summary of the computational biomechanical simulations that have been used to inform and develop a higher level of understanding of BHV tissues and their failure modes. Collectively, this information should serve as a tool not only to infer reliable and dependable prosthesis function, but also to instigate and facilitate the design of future bioprosthetic valves and clinically impact cardiology.

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“…The advances in the ultrasound technology (Hung et al 2007) and automatic segmentation of the images from ultrasound (c.f. (Pouch et al 2015)) during the last decade will be paramount to the successful implementation of our framework to clinical use.…”

Section: Imaging and Segmentationmentioning

confidence: 98%

“…Recent advancements in 3D ultrasound technology provide an opportunity to obtain patient-specific valve images in vivo (Hung et al 2007;Pouch et al 2015). As one can obtain the shape of the leaflet as it is loaded during the closing phase of the valve using in vivo imaging technology (e.g., ultrasound), in principle, it is possible to extract the biomechanical properties using a "full inverse model."…”

Section: Introductionmentioning

confidence: 99%

An inverse modeling approach for semilunar heart valve leaflet mechanics: exploitation of tissue structure

Aggarwal

Sacks

2015

Biomech Model Mechanobiol

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Determining the biomechanical behavior of heart valve leaflet tissues in a noninvasive manner remains an important clinical goal. While advances in 3D imaging modalities have made in vivo valve geometric data available, optimal methods to exploit such information in order to obtain functional information remain to be established. Herein we present and evaluate a novel leaflet shape-based framework to estimate the biomechanical behavior of heart valves from surface deformations by exploiting tissue structure. We determined accuracy levels using an "ideal" in vitro dataset, in which the leaflet geometry, strains, mechanical behavior, and fibrous structure were known to a high level of precision. By utilizing a simplified structural model for the leaflet mechanical behavior, we were able to limit the number of parameters to be determined per leaflet to only two. This approach allowed us to dramatically reduce the computational time and easily visualize the cost function to guide the minimization process. We determined that the image resolution and the number of available imaging frames were important components in the accuracy of our framework. Furthermore, our results suggest that it is possible to detect differences in fiber structure using our framework, thus allowing an opportunity to diagnose asymptomatic valve diseases and begin treatment at their early stages. Lastly, we observed good agreement of the final resulting stress-strain response when an averaged fiber architecture was used. This suggests that population-averaged fiber structural data may be sufficient for the application of the present framework to in vivo studies, although clearly much work remains to extend the present approach to in vivo problems.

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Segmentation of the Aortic Valve Apparatus in 3D Echocardiographic Images: Deformable Modeling of a Branching Medial Structure

Cited by 8 publications

References 10 publications

In-vivo heterogeneous functional and residual strains in human aortic valve leaflets

In-vivo heterogeneous functional and residual strains in human aortic valve leaflets

Biomechanical Behavior of Bioprosthetic Heart Valve Heterograft Tissues: Characterization, Simulation, and Performance

An inverse modeling approach for semilunar heart valve leaflet mechanics: exploitation of tissue structure

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