Date Published: October 8, 2018
Publisher: Public Library of Science
Author(s): Jihye Jang, Cory M. Tschabrunn, Michael Barkagan, Elad Anter, Bjoern Menze, Reza Nezafat, Wolfgang Rudolf Bauer.
Visualization of the complex 3D architecture of myocardial scar could improve guidance of radio-frequency ablation in the treatment of ventricular tachycardia (VT). In this study, we sought to develop a framework for 3D holographic visualization of myocardial scar, imaged using late gadolinium enhancement (LGE), on the augmented reality HoloLens. 3D holographic LGE model was built using the high-resolution 3D LGE image. Smooth endo/epicardial surface meshes were generated using Poisson surface reconstruction. For voxel-wise 3D scar model, every scarred voxel was rendered into a cube which carries the actual resolution of the LGE sequence. For surface scar model, scar information was projected on the endocardial surface mesh. Rendered layers were blended with different transparency and color, and visualized on HoloLens. A pilot animal study was performed where 3D holographic visualization of the scar was performed in 5 swines who underwent controlled infarction and electroanatomic mapping to identify VT substrate. 3D holographic visualization enabled assessment of the complex 3D scar architecture with touchless interaction in a sterile environment. Endoscopic view allowed visualization of scar from the ventricular chambers. Upon completion of the animal study, operator and mapping specialist independently completed the perceived usefulness questionnaire in the six-item usefulness scale. Operator and mapping specialist found it useful (usefulness rating: operator, 5.8; mapping specialist, 5.5; 1–7 scale) to have scar information during the intervention. HoloLens 3D LGE provides a true 3D perception of the complex scar architecture with immersive experience to visualize scar in an interactive and interpretable 3D approach, which may facilitate MR-guided VT ablation.
Late gadolinium enhancement (LGE) imaging in cardiovascular magnetic resonance (CMR) is a clinical gold standard for imaging of the myocardial scar . LGE has been used to identify extent, volume, and characteristics of myocardial scar in patients with prior myocardial infarction [1, 2]. In particular, the detailed scar depiction of the LGE has been suggested to be useful for planning and guiding scar-related ventricular tachycardia (VT) ablation by characterizing location and extent of the scar [3, 4].
We propose a framework for 3D holographic visualization based on the high-resolution 3D LGE images to generate a 3D myocardial scar model and visualize on HoloLens (Microsoft, Redmond, WA). An overview of the proposed framework is presented in Fig 1, and detailed processing pipelines for 3D volumetric and endocardial projection of the scar are presented in the following sections.
An extensive LGE was observed in the anterior-septal regions in 8 weeks-post myocardial infarction swine. The distribution of the LGE was complex, with the areas of transmural or near transmural scar and subendocardial sparring. The overall LGE volume was 9.2 ± 7.5% of the entire left ventricular myocardial volume, with the endocardial portion of the LGE corresponds to 34.8 ± 8.6% of the total scar volume. The percentage of the LGE area projected on the endocardial surface was 13.8 ± 9.4%. The endocardial LGE surface regions corresponded to the bipolar voltage amplitude < 1.5 mV in the electroanatomic mapping. We present a framework for 3D visualization of the high-resolution 3D LGE of myocardial scar in a holographic manner on the augmented-reality glass HoloLens. High-resolution 3D LGE sequence was used to image the myocardial scar, and 3D rendered LGE model was generated and visualized on HoloLens 3D Viewer Beta. HoloLens 3D LGE was tested in the swine model of myocardial infarction with electrophysiology study of arrhythmogenic substrate mapping. Operator and mapping specialist interacted with HoloLens 3D LGE to review the extent and the structure of 3D myocardial scar and compared with the electroanatomic mapping data. Both operator and mapping specialist found HoloLens 3D LGE useful with a usefulness rating of 5.8 and 5.5, on a scale from 1 to 7, respectively. Holographic visualization of the 3D LGE images provides a true 3D perception of the complex scar architecture with immersive experience to explore the 3D LGE in a more interactive and interpretable way. Source: http://doi.org/10.1371/journal.pone.0205188