Non-invasive in vivo time-dependent strain measurement method in human abdominal aortic aneurysms: Towards a novel approach to rupture risk estimation

Nagy, Róbert; Csobay-Novák, Csaba; Lovas, Attila; Sótonyi, Péter; Bojtár, Imre

doi:10.1016/j.jbiomech.2015.04.030

Cited by 9 publications

(13 citation statements)

References 44 publications

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“…The real patient‐specific kinematic field of an aneurysmatic abdominal aorta wall was obtained by in vivo ECG‐gatedCTA‐based displacement measurements of the lumen following the procedure proposed in Nagy et al Although the details of the lumen motion reconstruction are found there, we will now summarize the basic steps.…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

“…From the resulting grayscale voxel data, the points of the lumen were obtained by a 2D active contour algorithm in every slice and time step (Nagy et al and cited references). Since the total displacement range of a material point is comparable with the estimated measurement precision (identified by the voxel size in the transverse direction), Nagy et al construct a bi‐cubic spline surface, S ' k ( θ , z ), over the point cloud obtained by the active contour model in each time step:

boldS'_{k} ((),, θ, z) = \sum_{j = 1}^{n_{z}} \sum_{i = 1}^{n_{ϕ}} N_{i} ((), θ) M_{j} ((), z) boldW'_{ijk}, k = 1 \dots n_{t},

…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

“…where θ, z , and t are the circumferential, axial, and time variables, respectively, N i (θ) and M j ( z ) are the cubic uniform B‐spline basis functions of the two dimensions, n θ and n z are the corresponding knot numbers, n t = 100 is the number of the refined time steps, and W ' ijk is the 3D knot coordinates in the k th time step. The knot numbers in the two spatial dimensions θ and z determine the goodness of the fit, and according to the procedure presented in Nagy et al, the optimal values n θ = 42 and n z = 60 were obtained.…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

“…The motion tracking of the reference surface points is then solved by the auxiliary restriction of periodicity of the movement, resulting in the motion function of the lumen. Nagy et al introduced the periodic displacement function of the knot coordinates, given by the trigonometric series in Equation :

W_{ij} ((), t) = W_{italicij 0}^{A} + \sum_{k = 1}^{n_{f}} W_{ijk}^{A} \cos ((), \frac{2 italicπk}{T_{c}} t) + W_{ijk}^{B} \sin ((), \frac{2 italicπk}{T_{c}} t),

…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

“…The tool is based on a numerical smoothed particle hydrodynamic (SPH) mesh‐free model, which simulates the flow field and the blood‐induced loads assuming moving arterial walls. Displacement of the aortic wall is computed starting from the data recorded in an electrocardiogram‐gated–computed tomography angiography (ECG‐gated CT‐angiography [CTA]), which makes it possible to derive the kinematic field of a real patient‐specific AAA test case during a stabilized cardiac cycle, using the methodology recently proposed in Nagy et al…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the hemodynamic flow conditions and blood‐induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model

Aricò

Sinagra

Nagy

et al. 2019

Numer Methods Biomed Eng

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The estimation of blood flow-induced loads occurring on the artery wall is affected by uncertainties hidden in the complex interaction of the pulsatile flow, the mechanical parameters of the artery, and the external support conditions. To circumvent these difficulties, a specific tool is developed by combining the aorta displacements measured by an electrocardiogram-gated-computed tomography angiography, with the blood velocity field computed by a smoothed particle hydrodynamics (SPH) numerical model. In the present work, the SPH model has been specifically adapted to the solution of the 3D Navier-Stokes equations inside a domain with boundaries of prescribed motion. Images of the abdominal aorta aneurysm (AAA) of a 44-year-old female patient were acquired during a stabilized cardiac cycle by electrocardiogram-gated-computed tomography angiography. The in vivo kinematic field inside the pulsating arterial wall was estimated by using recent technology, which makes it possible to follow the shape of the arterial wall during a cardiac cycle. We compare the flow conditions and the blood-induced loads, computed by the numerical model under the assumption of a moving arterial wall, with the corresponding results obtained assuming three rigid wall geometries of the vessel during the cardiac cycle. Significant differences were found for the wall shear stress distribution. K E Y W O R D Saneurysm, arterial wall, infrarenal abdominal aorta, moving boundary, shear stresses, SPH | INTRODUCTIONAbdominal aortic aneurysms (AAAs) are localized and permanent dilatation of the infrarenal abdominal aorta. The related health risk is due to thrombus growth and development, rupture of the aortic wall, and degenerative effects of endothelial cells because of alteration of the flow field inside the aortic lumen. 1 The origin and development of AAAs are not clearly understood. The coupling between physiological changes of the intimal and medial layers of the arterial wall and the mechanical stimuli of the hemodynamic stresses acting on the vessel wall could be one of the origins. 2-5 Past studies 6,7 have shown that the "disturbed" flow conditions inside the lumen, such as regions of high and very low values of wall shear stress (WSS), and large temporal and spatial WSS gradients,

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Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

boldS'_{k} ((),, θ, z) = \sum_{j = 1}^{n_{z}} \sum_{i = 1}^{n_{ϕ}} N_{i} ((), θ) M_{j} ((), z) boldW'_{ijk}, k = 1 \dots n_{t},

…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

W_{ij} ((), t) = W_{italicij 0}^{A} + \sum_{k = 1}^{n_{f}} W_{ijk}^{A} \cos ((), \frac{2 italicπk}{T_{c}} t) + W_{ijk}^{B} \sin ((), \frac{2 italicπk}{T_{c}} t),

…”

Section: The In Vivo Procedures For Calculation Of the Kinematic Fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Investigation of the hemodynamic flow conditions and blood‐induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model

Aricò

Sinagra

Nagy

et al. 2019

Numer Methods Biomed Eng

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show abstract

Review of Patient-Specific Vascular Modeling: Template-Based Isogeometric Framework and the Case for CAD

Urick

Sanders

Hossain

et al. 2017

Arch Computat Methods Eng

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The role of biomechanics in aortic aneurysm management: requirements, open problems and future prospects

Farotto

Segers

Meuris

et al. 2018

Journal of the Mechanical Behavior of Biomedical Materials

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Non-invasive in vivo time-dependent strain measurement method in human abdominal aortic aneurysms: Towards a novel approach to rupture risk estimation

Cited by 9 publications

References 44 publications

Investigation of the hemodynamic flow conditions and blood‐induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model

Investigation of the hemodynamic flow conditions and blood‐induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model

Review of Patient-Specific Vascular Modeling: Template-Based Isogeometric Framework and the Case for CAD

The role of biomechanics in aortic aneurysm management: requirements, open problems and future prospects

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