Pranav Bhagirath

190 Chapter 10 ABSTRACT Background: Inverse potential mapping (IPM) non-invasively reconstructs cardiac surface potentials (CSP) using body surface potentials (BSP). This requires a volume conductor model (VCM), usually constructed from computed tomography (CT). CT however, exposes the patient to harmful radiation and lacks information about tissue structure. Magnetic resonance imaging (MRI), in contrast, is not associated with this limitation, and might be of advantage for mapping purposes. This feasibility study investigated an MRI-based IPM approach. In addition, the impact of incorporating the lungs and their particular resistivity values was explored. Methods and Results: Three volunteers and eight patients with premature ventricular contractions (PVC) scheduled for ablation underwent 65 electrodes BSP mapping. VCM was created using MRI. CSP were estimated from BSP and used to determine the origin of electrical activation. The IPM defined origin of sinus rhythm corresponded well with the anatomical position of the sinus node as described in the literature. In patients, the IPM derived PVC focus was 3-dimensionally located within 8.3±2.7 mm to the invasively determined focus using electro-anatomical mapping (EAM). The impact of lungs on the IPM was investigated using homogeneous and inhomogeneous VCM’s. The inhomogeneous VCM, incorporating lung specific conductivity, provided more accurate results compared to homogeneous VCM (8.3±2.7 mm and 10.3±3.1 mm respectively ( p=0.043 ). The inter-observer agreement was high for homogeneous (ICC=0.862, p=0.003 ) and inhomogeneous (ICC=0.812, p=0.004 ) VCM. Conclusion: MRI based whole-heart inverse potential mapping enables accurate spatial localization of sinus rhythm and PVC, comparable to EAM. An inhomogeneous volume conductor model improved inverse potential mapping accuracy.