Multi-modal Validation Framework of Mitral Valve Geometry and Functional Computational Models

Grbić, Saša; Easley, Thomas F.; Mansi, Tommaso; Bloodworth, Charles H.; Pierce, Eric T.; Voigt, Ingmar; Neumann, Dominik; Krebs, Julian; Yuh, David D.; Jensen, Morten Ø.; Comanicìu, Dorin; Yoganathan, Ajit P.

doi:10.1007/978-3-319-14678-2_25

Cited by 2 publications

(4 citation statements)

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“…It was mounted in the extensively validated Georgia Tech Left Heart Simulator (GTLHS) and positioned to a healthy geometry using previously described methods. 9, 20, 24 To assess the positional tracking capacity of the new method, a dense marker mesh (target: 2 mm between markers) was attached across the annulus and both leaflets. This was imaged twice by μCT: first open and relaxed, then statically closed under steady systolic air pressure (120 mmHg), using recently developed methods.…”

Section: Methodsmentioning

confidence: 99%

“…This was imaged twice by μCT: first open and relaxed, then statically closed under steady systolic air pressure (120 mmHg), using recently developed methods. 9 The air used to pressurize the model left ventricle was first humidified by passing through warm water; this prevented tissue dehydration during imaging.…”

Section: Methodsmentioning

confidence: 99%

“…7, 17, 19 To this end, earlier idealized geometric models are giving way to those with unprecedented structural detail. 9, 17, 25 These pursuits are facilitated by the increased availability of micro-computed tomography (μCT), which, with voxel resolution as fine as 9–17 μm, 11 has rapidly become a gold-standard against which other structural imaging modalities are evaluated. 2, 5, 15, 30 Yet standalone structures, though necessary, are insufficient to fully characterize the finer aspects of a tissue’s mechanics.…”

Section: Introductionmentioning

confidence: 99%

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Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve

et al. 2015

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Increasing availability of micro-computed tomography (μCT) as a structural imaging gold-standard is bringing unprecedented geometric detail to soft tissue modeling. However, the utility of these advances is severely hindered without analogous enhancement to the associated kinematic detail. To this end, labeling and following discrete points on a tissue across various deformation states is a well-established approach. Still, existing techniques suffer limitations when applied to complex geometries and large deformations and strains. Therefore, we herein developed a non-destructive system for applying fiducial markers (minimum diameter: 500μm) to soft tissue and tracking them through multiple loading conditions by μCT. Using a novel applicator to minimize adhesive usage, four distinct marker materials were resolvable from both tissue and one another, without image artifacts. No impact on tissue stiffness was observed. μCT addressed accuracy limitations of stereophotogrammetry (inter-method positional error 1.2±0.3mm, given marker diameter 1.9±0.1mm). Marker application to ovine mitral valves revealed leaflet Almansi areal strains (45±4%) closely matching literature values, and provided radiographic access to previously inaccessible regions, such as the leaflet coaptation zone. This system may meaningfully support mechanical characterization of numerous tissues or biomaterials, as well as tissue-device interaction studies for regulatory standards purposes.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve

et al. 2015

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“…The experimental protocols using Georgia Tech CLHS were extensively validated as described in our previous publications. 15,24,38 Briefly, we first simulated the healthy hemodynamic conditions of the end-systolic state (100 mmHg TVP) to recover the fully closed configuration of MV apparatus. Then, each valve was placed in the bore of a Siemens Inveon scanner (Siemens Medical Solutions USA Inc., Malvern, PA) and imaged using the settings optimized for soft tissue imaging (80 kV energy, 500 μA intensity, 650 ms integration time).…”

Section: Data Acquisitionmentioning

confidence: 99%

Mitral Valve Chordae Tendineae: Topological and Geometrical Characterization

et al. 2016

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Mitral valve (MV) closure depends upon the proper function of each component of the valve apparatus, which includes the annulus, leaflets, and chordae tendineae (CT). Geometry plays a major role in MV mechanics and thus highly impacts the accuracy of computational models simulating MV function and repair. While the physiological geometry of the leaflets and annulus have been previously investigated, little effort has been made to quantitatively and objectively describe CT geometry. The CT constitute a fibrous tendon-like structure projecting from the papillary muscles (PMs) to the leaflets, thereby evenly distributing the loads placed on the MV during closure. Because CT play a major role in determining the shape and stress state of the MV as a whole, their geometry must be well characterized. In the present work, a novel and comprehensive investigation of MV CT geometry was performed to more fully quantify CT anatomy. In vitro micro-tomography 3D images of ovine MVs were acquired, segmented, then analyzed using a curve-skeleton transform. The resulting data was used to construct B-spline geometric representations of the CT structures, enriched with a continuous field of cross-sectional area (CSA) data. Next, Reeb graph models were developed to analyze overall topological patterns, along with dimensional attributes such as segment lengths, 3D orientations, and CSA. Reeb graph results revealed that the topology of ovine MV CT followed a full binary tree structure. Moreover, individual chords are mostly planar geometries that together form a 3D load-bearing support for the MV leaflets. We further demonstrated that, unlike flow-based branching patterns, while individual CT branches became thinner as they propagated further away from the PM heads towards the leaflets, the total CSA almost doubled. Overall, our findings indicate a certain level of regularity in structure, and suggest that population-based MV CT geometric models can be generated to improve current MV repair procedures.

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Multi-modal Validation Framework of Mitral Valve Geometry and Functional Computational Models

Cited by 2 publications

References 13 publications

Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve

Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve

Mitral Valve Chordae Tendineae: Topological and Geometrical Characterization

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