Accuracy of electroanatomical mapping-guided cardiac radiotherapy for ventricular tachycardia: pitfalls and solutions

Abstract

Aims To analyse and optimize the interobserver agreement for gross target volume (GTV) delineation on cardiac computed tomography (CCT) based on electroanatomical mapping (EAM) data acquired to guide radiotherapy for ventricular tachycardia (VT). Methods and results Electroanatomical mapping data were exported and merged with the segmented CCT using manual registration by two observers. A GTV was created by both observers for predefined left ventricular (LV) areas based on preselected endocardial EAM points indicating a two-dimensional (2D) surface area of interest. The influence of (interobserver) registration accuracy and availability of EAM data on the final GTV and 2D surface location within each LV area was evaluated. The median distance between the CCT and EAM after registration was 2.7 mm, 95th percentile 6.2 mm for observer #1 and 3.0 mm, 95th percentile 7.6 mm for observer #2 (P = 0.9). Created GTVs were significantly different (8 vs. 19 mL) with lowest GTV overlap (35%) for lateral wall target areas. Similarly, the highest shift between 2D surfaces was observed for the septal LV (6.4 mm). The optimal surface registration accuracy (2.6 mm) and interobserver agreement (Δ interobserver EAM surface registration 1.3 mm) was achieved if at least three cardiac chambers were mapped, including high-quality endocardial LV EAM. Conclusion Detailed EAM of at least three chambers allows for accurate co-registration of EAM data with CCT and high interobserver agreement to guide radiotherapy of VT. However, the substrate location should be taken in consideration when creating a treatment volume margin.

Case Report: Repeated Stereotactic Radiotherapy of Recurrent Ventricular Tachycardia: Reasons, Feasibility, and Safety

“…Using the novel method of co-registration of electroanatomical maps with pretreatment CT, we were able to correct the previous treatment plan and deliver successfully therapy ( 20 ). More recently, we showed reproducibility of this strategy ( 32 ). The other important issue related to accuracy and safety is how to minimalize the treatment volume with respiratory compensation.…”

Stereotactic Ablative Radiotherapy of Ventricular Tachycardia Using Tracking: Optimized Target Definition Workflow

“…Regarding possible alternative approaches, another logical approach when considering deformation for target definition is applying an initial CTV definition process (based on CARTO physiological mapping) to all secondary CT image series, followed again, by merging resulting subvolumes (including the aspect of potential undersampling). However, based on the publications, the method seems not to be sufficiently developed yet for, e.g., relatively large reported inter-observer variability ( 22 ) and likely deformation between CARTO surfaces and segmented CT anatomy to match. Repeating the whole target definition process for all motion sampling CT series using the current state of the process would be probably too laborious and affected by observer variations.…”

Stereotactic Radiotherapy: An Alternative Option for Refractory Ventricular Tachycardia to Drug and Ablation Therapy

“…Multimodal integration of the electroanatomic mapping with computed tomography (CT) planning could help accurately localize the target on the CT images [ 30 ]. High-quality endocardial-surface and -chamber mapping could help to precisely merge the information with cardiac CT [ 31 ]. The RAVENTA trial found remarkable differences between the electroanatomic mapping outcomes and target volume planning during VT radioablation [ 32 ].…”