A 4D visualization tool for treatment planning of non-invasive radioablation in patients with ventricular tachycardia

Non-invasive cardiac radioablation is an emerging therapy for the treatment of ventricular tachycardia (VT). Electrophysiologic, anatomic and molecular imaging studies are used to localize the breakout region of the VT, but current therapy planning is tedious and prone to error due to a lack of data integration. In this work we present the design and development of a software platform and workflow to facilitate precision-targeted therapy planning, including affine non-rigid multimodality image registration and 2D-3D-4D visualization across modalities. Registration accuracy was measured using Dice Similarity and Hausdorff Distance of total left ventricle tissue volumes, which were 0.914 ± 0.013 and 2.65mm ± 0.34mm, respectively (average ± standard deviation). Electrocardiographic maps of VT parameters were registered temporally to surface electrode data to recreate familiar ECG tracings. 2D polar maps, 3D slice-views, and 4D cine-renderings were used for hybrid fusion displays of molecular and electroanatomic images. Segmentations of the cardiac-gated contrast CT blood-pool and molecular images of perfusion and glucose metabolism were used to identify regions of fibrotic scar tissue and hibernating myocardium in the 3D scene. Ablation targets were painted onto the 2D polar map, 3D slice or 4D-cine views, and exported as DICOM for import to radiotherapy planning software. We anticipate that the combination of accurate multimodality image registration and visualizations will enable more reliable therapy planning, expedite treatment and may improve understanding of the underlying pathophysiology of these lethal arrhythmias.