A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data

Alrefae, Tareq; Smirnova, Irina V.; Cook, Larry T.; Bilgen, Mehmet

doi:10.1186/1475-925x-7-15

Cited by 4 publications

(10 citation statements)

References 21 publications

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“…Under a set of specific assumptions and considerations, however, reliable and repeatable models can be constructed to represent certain aspects of the LV wall motion. For example, from dynamic tMRIs, noticing that the rotation of the LV wall is negligible at the mid-ventricle level led to the formulation of a one-parameter model [8]. The current study extends this concept further and expresses the rotation as a superposition to the radial motion by introducing a second parameter into the previous one-parameter model.…”

Section: Introductionmentioning

confidence: 95%

“…However, the LV wall at mid-ventricle moves mostly in radial direction, meaning it contracts isotropically with negligible amount of rotation. Based on these unique characteristics, a simple one-parameter model was developed earlier to mathematically represent the motion field at the mid-ventricle [8]. The current study was under taken to increase the capacity of this empirical model further to account for the twist-type motions of the apex and base.…”

Section: Introductionmentioning

confidence: 99%

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Construction of a two-parameter empirical model of left ventricle wall motion using cardiac tagged magnetic resonance imaging data

et al. 2012

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BackgroundA one-parameter model was previously proposed to characterize the short axis motion of the LV wall at the mid-ventricle level. The single parameter of this model was associated with the radial contraction of myocardium, but more comprehensive model was needed to account for the rotation at the apex and base levels. The current study developed such model and demonstrated its merits and limitations with examples.Materials and methodsThe hearts of five healthy individuals were visualized using cardiac tagged magnetic resonance imaging (tMRI) covering the contraction and relaxation phases. Based on the characteristics of the overall dynamics of the LV wall, its motion was represented by a combination of two components - radial and rotational. Each component was represented by a transformation matrix with a time-dependent variable α or β.Image preprocessing step and model fitting algorithm were described and applied to estimate the temporal profiles of α and β within a cardiac cycle at the apex, mid-ventricle and base levels. During this process, the tagged lines of the acquired images served as landmark reference for comparing against the model prediction of the motion. Qualitative and quantitative analyses were performed for testing the performance of the model and thus its validation.ResultsThe α and β estimates exhibited similarities in values and temporal trends once they were scaled by the radius of the epicardium (repi)and plotted against the time scaled by the period of the cardiac cycle (Tcardiac) of each heart measured during the data acquisition. α/repi peaked at about Δt/Tcardiac=0.4 and with values 0.34, 0.4 and 0.3 for the apex, mid-ventricle and base level, respectively. β/repi similarly maximized in amplitude at about Δt/Tcardiac=0.4, but read 0.2 for the apex and - 0.08 for the base level. The difference indicated that the apex twisted more than the base.ConclusionIt is feasible to empirically model the spatial and temporal evolution of the LV wall motion using a two-parameter formulation in conjunction with tMRI-based visualization of the LV wall in the transverse planes of the apex, mid-ventricle and base. In healthy hearts, the analytical model will potentially allow deriving biomechanical entities, such as strain, strain rate or torsion, which are typically used as diagnostic, prognostic or predictive markers of cardiovascular diseases including diabetes.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Construction of a two-parameter empirical model of left ventricle wall motion using cardiac tagged magnetic resonance imaging data

et al. 2012

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“…Additional simulations were carried out to investigate the effects of tag line fading and image noise on phase interference using a midventricle LV wall model and also a model of its motion described in [2]. For this purpose, an image G(x,y) of size 256 9 256 pixels with uniform intensity 1 was formed.…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…This model was developed to simulate the forward systolic motion of the LV wall during the cardiac cycle by using a Gaussian function to introduce a radial deformation [2]. The resulting effect is equivalent to shifting image coordinates, so that the deformed state resembles the myocardial contraction and tag lines observed during the systole.…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…Tagged cine magnetic resonance imaging (tMRI) is an established radiological technique for evaluating contraction of left ventricle (LV) wall [1,2], and its applications are growing in other areas. Recent applications include mapping the elasticity variation in biologically soft tissue [3], measuring tongue motion [4] and imaging brain motion [5].…”

Section: Introductionmentioning

confidence: 99%

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Harmonic phase interference for the detection of tag line crossings and beyond in homogeneous strain analysis of cardiac tagged MRI data

Bilgen

2010

Australas Phys Eng Sci Med

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Homogenous strain analysis (HSA) was developed to evaluate regional cardiac function using tagged cine magnetic resonance images of heart. Current cardiac applications of HSA are however limited in accurately detecting tag intersections within the myocardial wall, producing consistent triangulation of tag cells throughout the image series and achieving optimal spatial resolution due to the large size of the triangles. To address these issues, this article introduces a harmonic phase (HARP) interference method. In principle, as in the standard HARP analysis, the method uses harmonic phases associated with the two of the four fundamental peaks in the spectrum of a tagged image. However, the phase associated with each peak is wrapped when estimated digitally. This article shows that special combination of wrapped phases results in an image with unique intensity pattern that can be exploited to automatically detect tag intersections and to produce reliable triangulation with regularly organized partitioning of the mesh for HSA. In addition, the method offers new opportunities and freedom for evaluating myocardial function when the power and angle of the complex filtered spectra are mathematically modified prior to computing the phase. For example, the triangular elements can be shifted spatially by changing the angle and/or their sizes can be reduced by changing the power. Interference patterns obtained under a variety of power and angle conditions were presented and specific features observed in the results were explained. Together, the advanced processing capabilities increase the power of HSA by making the analysis less prone to errors from human interactions. It also allows strain measurements at higher spatial resolution and multi-scale, thereby improving the display methods for better interpretation of the analysis results.

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The potential role of MRI in veterinary clinical cardiology

Gilbert

McConnell

Holden

et al. 2010

The Veterinary Journal

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A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data

Cited by 4 publications

References 21 publications

Construction of a two-parameter empirical model of left ventricle wall motion using cardiac tagged magnetic resonance imaging data

Construction of a two-parameter empirical model of left ventricle wall motion using cardiac tagged magnetic resonance imaging data

Harmonic phase interference for the detection of tag line crossings and beyond in homogeneous strain analysis of cardiac tagged MRI data

The potential role of MRI in veterinary clinical cardiology

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