Delay-Based Regularization for ECG Imaging of Transmembrane Voltages

Schuler, Steffen; Potyagaylo, Danila; Doessel, Olaf

doi:10.22489/cinc.2019.375

Cited by 3 publications

(5 citation statements)

References 7 publications

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“…1 were obtained using BEM. Although more sophisticated, spatio-temporal regularization methods exist [29], [9], [30], [31], [32], we decided to use purely spatial secondorder Tikhonov regularization for this comparison study because it is widely used in combination with both considered source models [33], [11]. The inverse solution was computed for all time steps simultaneously:…”

Section: Inverse Reconstructionmentioning

confidence: 99%

“…Consequently, TMVs share a uniform morphology. However, a spatially constant offset remains undetermined in reconstructed TMVs, requiring a baseline correction [32]. This baseline correction in conjunction with subsequent temporal smoothing exploits the temporal structure of TMVs to overcome ambiguities during AT estimation (only one deflection remains after sufficient smoothing) and may be seen as a way to leverage prior knowledge for AT estimation.…”

Section: A Line-of-block Artifactsmentioning

confidence: 99%

“…While promising results have been reported [21], [20], this approach is sensitive to the initialization of the nonconvex optimization and to cases where TMVs may not match the assumed waveform, such as in the case of depression of TMV magnitude in ischemia [51]. In linear formulations of the inverse problem, on the other hand, spatial smoothing of reconstructed sources may be mitigated as well by using temporal priors for inverse reconstructions [30], [52], [32].…”

Section: A Line-of-block Artifactsmentioning

confidence: 99%

“…However, transmural regularization is essential because TCs on opposite sides of the myocardial wall show strong linear dependence (opposite signs). Furthermore, ambiguities exist between the septum and the free walls, which may only be resolved using temporal regularization [30], [32].…”

Section: Source Modelsmentioning

confidence: 99%

See 3 more Smart Citations

Reducing Line-of-Block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

Schuler

Schaufelberger

Bear

et al. 2022

IEEE Trans. Biomed. Eng.

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Section: Inverse Reconstructionmentioning

confidence: 99%

Section: A Line-of-block Artifactsmentioning

confidence: 99%

Section: A Line-of-block Artifactsmentioning

confidence: 99%

Section: Source Modelsmentioning

confidence: 99%

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Reducing Line-of-Block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

Schuler

Schaufelberger

Bear

et al. 2022

IEEE Trans. Biomed. Eng.

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“…For TMVs, the baseline correction in [6] was applied after reconstructions to correct for ambiguous spatial offsets.…”

Section: Ecgi Reconstructionsmentioning

confidence: 99%

Comparison of Activation Times Estimation for Potential-Based ECG Imaging

Schaufelberger¹,

Schuler²,

Bear³

et al. 2019

2019 Computing in Cardiology Conference (CinC)

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Activation times (AT) represent the sequence of cardiac depolarization and are one of the most important parameters of cardiac electrical activity. However, estimation of ATs is challenging due to multiple sources of noise. If ATs are estimated from signals reconstructed using electrocardiographic imaging (ECGI), additional problems can arise due to over-smoothing or ambiguities in the inverse problem. Resulting AT maps can show falsely homogeneous regions or artificial lines of block. As ATs are not only important clinically, but are also used for evaluation of ECGI, it is important to understand where these errors come from.We present results from a community effort to compare AT estimation methods on a common dataset of simulated ventricular pacings. ECGI reconstructions were performed in terms of transmembrane voltages as well as epi-endo and pericardial potentials, all using 2nd-order Tikhonov and 6 regularization parameters. ATs were then estimated by the participants and compared to the truth.While the pacing site had the largest effect on AT correlation coefficients (CC), there were also differences between methods and source models that were poorly reflected in CCs. Results indicate that artificial lines of block are most severe for purely temporal methods. Compared to the other source models, ATs estimated from transmembrane voltages are more precise and less prone to artifacts.

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Reducing Line-of-block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

Schuler,

Schaufelberger,

Bear

et al. 2021

Preprint

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To investigate cardiac activation maps estimated using electrocardiographic imaging and to find methods reducing line-of-block (LoB) artifacts, while preserving real LoBs. Methods: Body surface potentials were computed for 137 simulated ventricular excitations. Subsequently, the inverse problem was solved to obtain extracellular potentials (EP) and transmembrane voltages (TMV). From these, activation times (AT) were estimated using four methods and compared to the ground truth. This process was evaluated with two cardiac mesh resolutions. Factors contributing toLoB artifacts were identified by analyzing the impact of spatial and temporal smoothing on the morphology of source signals. Results: AT estimation using a spatiotemporal derivative performed better than using a temporal derivative. Compared to deflection-based AT estimation, correlation-based methods were less prone to LoB artifacts but performed worse in identifying real LoBs. Temporal smoothing could eliminate artifacts for TMVs but not for EPs, which could be linked to their temporal morphology. TMVs led to more accurate ATs on the septum than EPs. Mesh resolution had a negligible effect on inverse reconstructions, but small distances were important for cross-correlation-based estimation of AT delays. Conclusion: LoB artifacts are mainly caused by the inherent spatial smoothing effect of the inverse reconstruction. Among the configurations evaluated, only deflection-based AT estimation in combination with TMVs and strong temporal smoothing can prevent LoB artifacts, while preserving real LoBs. Significance: Regions of slow conduction are of considerable clinical interest and LoB artifacts observed in non-invasive ATs can lead to misinterpretations. We addressed this problem by identifying factors causing such artifacts and methods to reduce them.

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Delay-Based Regularization for ECG Imaging of Transmembrane Voltages

Cited by 3 publications

References 7 publications

Reducing Line-of-Block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

Reducing Line-of-Block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

Comparison of Activation Times Estimation for Potential-Based ECG Imaging

Reducing Line-of-block Artifacts in Cardiac Activation Maps Estimated Using ECG Imaging: A Comparison of Source Models and Estimation Methods

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