The Evolution of Tissue Stiffness at Radiofrequency Ablation Sites During Lesion Formation and in the Peri‐Ablation Period

Eyerly, Stephanie A.; Vejdani‐Jahromi, Maryam; Dumont, Douglas M.; Trahey, Gregg E.; Wolf, Patrick D.

doi:10.1111/jce.12709

Cited by 28 publications

(23 citation statements)

References 38 publications

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“…The data were acquired under an open-chest preparation as described in Eyerly et al [37]. For the NCC and the Bayesian estimators, the same parameters described in Table II were used, except the kernel length and kernel overlap factor are slightly smaller due to the higher center-frequency ( f c =8 MHz).…”

Section: Methodsmentioning

confidence: 99%

Robust Tracking of Small Displacements With a Bayesian Estimator

Dumont

Byram

2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Radiation-force-based elasticity imaging describes a group of techniques that use acoustic radiation force (ARF) to displace tissue in order to obtain qualitative or quantitative measurements of tissue properties. Because ARF-induced displacements are on the order of micrometers, tracking these displacements in vivo can be challenging. Previously, it has been shown that Bayesian-based estimation can overcome some of the limitations of a traditional displacement estimator like normalized cross-correlation (NCC). In this work, we describe a Bayesian framework that combines a generalized Gaussian-Markov random field (GGMRF) prior with an automated method for selecting the prior’s width. We then evaluate its performance in the context of tracking the micrometer-order displacements encountered in an ARF-based method like acoustic radiation force impulse (ARFI) imaging. The results show that bias, variance, and mean-square error performance vary with prior shape and width, and that an almost one order-of-magnitude reduction in mean-square error can be achieved by the estimator at the automatically-selected prior width. Lesion simulations show that the proposed estimator has a higher contrast-to-noise ratio but lower contrast than NCC, median-filtered NCC, and the previous Bayesian estimator, with a non-Gaussian prior shape having better lesion-edge resolution than a Gaussian prior. In vivo results from a cardiac, radiofrequency ablation ARFI imaging dataset show quantitative improvements in lesion contrast-to-noise ratio over NCC as well as the previous Bayesian estimator.

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Section: Methodsmentioning

confidence: 99%

Robust Tracking of Small Displacements With a Bayesian Estimator

Dumont

Byram

2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The acute change in tissue stiffness associated with cardiac ablation lesions has been characterized using this technique 9 . Recently, the feasibility of transthoracic cardiac SWEI measurements in humans have been used to characterize diastolic stiffness 10 .…”

Section: Introductionmentioning

confidence: 99%

Quantifying Myocardial Contractility Changes Using Ultrasound-Based Shear Wave Elastography

Vejdani‐Jahromi

Freedman

Nagle

et al. 2017

Journal of the American Society of Echocardiography

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BACKGROUND Myocardial contractility, a significant determinant of cardiac function, is valuable for diagnosis and evaluation of treatment in cardiovascular disorders including heart failure. Shear Wave Elasticity Imaging (SWEI) is a newly developed ultrasound-based elastography technique that can directly assess the stiffness of cardiac tissue. The aim of the study was to verify the ability of technique to quantify contractility changes in the myocardium. METHODS In 12 isolated rabbit hearts we made SWEI measurements of systolic stiffness at 5 different coronary perfusion pressures from 0 to 92 mmHg. The changes in coronary perfusion were used to induce acute stepwise reversible changes in cardiac contractility via the Gregg effect. The Gregg effect is the dependency of contractility on coronary perfusion. In 4 of the hearts, we repeated the measurements after delivery of Gadolinium, which is known to block the Gregg effect. RESULTS Systolic stiffness measured by SWEI changed linearly with coronary perfusion pressure with a slope of 0.27 kPa/mmHg (mean of 95% CI, R2=0.73). As expected the change in contractility due to the Gregg effect was blocked by Gadolinium with a significant reduction of the slope to 0.08 kPa/mmHg. CONCLUSION SWEI measurements of systolic stiffness provide an index of contractility in the unloaded isolated rabbit heart. While this study was done under ideal imaging conditions and with non-physiological loading conditions, it reinforces the concept that this ultrasound technique has the potential to provide a direct and noninvasive index of cardiac contractility.

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“…However, these on axis displacements can be used to visualize the relative stiffness difference in the tissue along planes of constant intensity. This technique has been used in the laboratory and clinically to visualize liver tumors, breast lesions and cardiac ablation lesions [1], [5], [6]. …”

Section: Introductionmentioning

confidence: 99%

A Comparison of Acoustic Radiation Force-Derived Indices of Cardiac Function in the Langendorff Perfused Rabbit Heart

Vejdani‐Jahromi

Nagle

Yang

et al. 2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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In the past decade, there has been an increased interest in characterizing cardiac tissue mechanics utilizing newly developed ultrasound-based elastography techniques. These methods excite the tissue mechanically and track the response. Two frequently used methods, acoustic radiation force impulse and shear wave elasticity imaging (ARFI and SWEI), have been considered qualitative and quantitative techniques providing relative and absolute measures of tissue stiffness respectively. Depending on imaging conditions, it is desirable to identify indices of cardiac function that could be measured by ARFI and SWEI and to characterize the relationship between the measures. In this study, we have compared two indices (i.e. relaxation time constant used for diastolic dysfunction assessment and systolic/diastolic stiffness ratio) measured nearly simultaneously by M-mode ARFI and SWEI techniques. We additionally correlated ARFI-measured inverse displacements with SWEI measured values of the shear modulus of stiffness. For the eight animals studied, the average relaxation time constant ( ) measured by ARFI and SWEI were (69±18 ms, R2=0.96) and (65±19 ms, R2=0.99), (ARFI-SWEI inter-rater agreement = 0.90). Average systolic/diastolic stiffness ratio for ARFI, and SWEI measurements were 6.01±1.37 and 7.12±3.24 respectively (agreement=0.70). Shear modulus of stiffness (SWEI) was linearly related to inverse displacement values (ARFI) with a 95% CI for the slope of 0.010–0.011 (1/μm)/(kPa) (R2=0.73). In conclusion, the relaxation time constant and the systolic/diastolic stiffness ratio were calculated with good agreement between the ARFI and SWEI derived measurements. ARFI relative and SWEI absolute stiffness measurements were linearly related with varying slopes based on imaging conditions and subject tissue properties.

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The Evolution of Tissue Stiffness at Radiofrequency Ablation Sites During Lesion Formation and in the Peri‐Ablation Period

Cited by 28 publications

References 38 publications

Robust Tracking of Small Displacements With a Bayesian Estimator

Robust Tracking of Small Displacements With a Bayesian Estimator

Quantifying Myocardial Contractility Changes Using Ultrasound-Based Shear Wave Elastography

A Comparison of Acoustic Radiation Force-Derived Indices of Cardiac Function in the Langendorff Perfused Rabbit Heart

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