Accuracy and clinical feasibility of 3D-myocardial thickness map measured by cardiac computed tomogram

Abstract

Background: Although myocardial thickness is an important variable for therapeutic catheter ablation of cardiac arrhythmias, quantification of wall thickness has been overlooked. We developed a software (AMBER) that measures 3D-myocardial thickness using a cardiac computed tomogram (CT) image, verified its accuracy, and tested its clinical feasibility. Methods: We generated 3D-thickness maps by calculating wall thickness (WT) from the CT images of 120 patients' hearts and a 3D-phantom model (PhM). The initial vector field of the Laplace equation was oriented to calculate WT with the field lines derived from the 3D mesh. We demonstrate the robustness of the Laplace WT algorithm by comparing with the real thickness of 3D-PhM, echocardiographically measured left ventricular (LV) WT, and regional left atrial (LA) WT reported from previous studies. We conducted a pilot case of catheter ablation for atrial fibrillation (AF) utilizing real-time LAWT map-guided radiofrequency (RF) energy titration. Results: AMBER 3D-WT had excellent correlations with the real thickness of the PhM (R = 0.968, p < 0.001) and echocardiographically measured LVWT in 10 patients (R = 0.656, p = 0.007). AMBER 3D-LAWT (n = 120) showed a relatively good match with 12 previously reported regional LAWT. We successfully conducted pilot AF ablation utilizing AMBER 3D-LAWT map-guided real-time RF energy titration. Conclusion: We developed and verified an AMBER 3D-cardiac thickness map measured by cardiac CT images for LAWT and LVWT, and tested its feasibility for RF energy titration during clinical catheter ablation.

Risk Factors for Stiff Left Atrial Physiology 1 Year After Catheter Ablation of Atrial Fibrillation

“…We developed a customized software (AMBER, Laonmed Inc., Seoul, Korea) that measured the LA wall thickness by applying Laplace's equation in the cardiac CT images (Kwon et al, 2020 ; Lee et al, 2021b ). The CT scan was conducted within a month before the AFCA.…”

“…The spatial resolution of the CT was set to the normalized vector in the 3D Euclidean space. The methods and principles of the customized software (AMBER) were previously described in detail, and the results have been well validated with a 3D printed phantom model in 120 patients (Kwon et al, 2020 ; Lee et al, 2021b ). In brief, the endocardium of the LA was semiautomatically divided on the cardiac CT using an edge detector.…”

Left Atrial Wall Stress and the Long-Term Outcome of Catheter Ablation of Atrial Fibrillation: An Artificial Intelligence-Based Prediction of Atrial Wall Stress

“…AF, atrial fibrillation; AFCA, atrial fibrillation catheter ablation; AI, artificial intelligence; LAW-stress, left atrial wall stress. (Kwon O. S. et al, 2020;Lee et al, 2021). The number of rows and columns of CT image pixels were 512, and the number of slices was approximately 320 at the z-axis.…”

“…The spatial resolution of CT was set to the normalized vector in 3D Euclidean space. The methods and principles of the customized software (AMBER) were previously described in detail, and the results have been well validated with a 3D printed phantom and in 120 patients (Kwon O. S. et al, 2020;Lee et al, 2021). In brief, the endocardium of the LA was semi-automatically divided on the cardiac CT by using the edge detector.…”

“…This is because the atrial structure is complex, LA pressure measurements require an invasive procedure, and there is no standard for measuring thin atrial wall thickness. Therefore, we calculated this complex parameter, the LAW-stress [measured] , by using the direct LA pressure measured during AFCA (Park et al, 2014(Park et al, , 2019 and CT-based mean LA wall thickness measured using customized software (AMBER, Laonmed, South Korea) (Kwon O. S. et al, 2020). LAWstress is a comprehensive parameter that reflects not only LA size but also LA hemodynamic status and innate patient characteristics, such as regional LA wall thickness.…”