MR-guided RF Ablation

Background: Cardiac arrhythmias are common, affecting 3-5 % of the over 40s. Population growth and ageing will lead to a large increase in new arrhythmia cases [1]. Cardiac arrhythmias cause considerable morbidity and significant mortality as well as considerable anxiety in patients and their relatives. Early and accurate diagnosis is essential for the selection of an appropriate treatment, which can be drug or ablation treatment. Once the arrhythmogenic substrate is fully elucidated then it is often possible to complete cure the condition by either burning the endocardial surface where the abnormal electrical activity is originating to block the propagation of the abnormal electrical activity. This procedure is called radio-frequency (RF) ablation as the most common technique used is deposition of heat using RF energy via specially adapted catheters. Currently, X-ray fluoroscopy is the standard technique used for image guidance. Since this imaging modality offers no 3D information and no soft tissue contrast, the procedure normally takes several hours, with fluoroscopy and thus radiation exposure taking up a large fraction of this time. Electro-anatomical mapping systems (Biosense Webster Carto, California, USA, and St Jude Medical ESI, Minnesota USA) generate static anatomical maps by tracking the electrical catheters or recently by importing a static` 3D image dataset (CT or MRI). However, there is a degree of inaccuracy in the registration of the MR or CT derived and mapping catheter-derived surfaces.