MR guided cardiac RF ablation – TACIT

The objectives of this research project are to develop fast and reliable cardiac MR thermometry in order to improve the efficacy and safety of Radio-frequency ablation (RFA) for patients. RFA using a dedicated catheter has proved effective to treat cardiac arrhythmia. However, the lack of real time visualization of thermal lesion formation in current clinical practice prevents the physician from evaluating the size of the lesion during the procedure. Insufficient energy delivery to the cardiac muscle may lead to incomplete (non transmural) ablation and arrhythmia recurrences, whereas excessive heating may lead to intratissular explosion (pop) and rupture of the cardiac muscle leading to tamponade. In addition, extracardiac lesions are potentially devastating when leading to lethal atrio-oesophageal fistulas. MRI offers the possibility to map the temperature distribution in soft tissues in real-time with several images per second and with a spatial resolution in the order of one millimeter. Real-time cardiac MR thermometry remains challenging because of complex motion of the organ associated with respiration and contraction of the heart.
In this “TACIT” project, MR acquisition methods, real-time image processing and dedicated MR compatible instrumentation will be developed to allow online visualization of thermal lesion formation during the RF ablation procedure. Main technical challenges include development of rapid MR acquisition sequences with sufficient image resolution (~1 mm) to visualize lesion formation in the heart, real-time image processing (including motion compensation) automatic feedback control for optimized RF energy delivery, display of temperature images and calculation of accumulated thermal dose maps. This will be conducted together with the development of MR compatible RF catheters allowing for RF delivery, while simultaneously recording electrograms and acquiring high resolution MR temperature images.
Practical evaluation of the feasibility of such a procedure and evaluation of the accumulated thermal dose as a predictor of transmural ablations will be conducted on ex vivo isolated perfused hearts and in vivo in large animals at the “Plateforme Technologique d’Innovation Biomedicale” (PTIB, University Hospital X Arnozan - Pessac), which is equipped with a coupled MR/X-RAY suite. These developments should fill in a gap in knowledge in the field of monitoring lesion formation during catheter ablation. The expected benefit for patients and health care systems would include increased safety and efficacy, reduced recurrence rates and rates of costly redo procedures. These optimized ablation will be used to treat the commonly targeted arrhythmias: Atrial Fibrillation, Ventricular tachycardia, etc….
This project aims to develop and evaluate in vivo a full set of instrumentation, methodologies and control procedures that should be transferred to clinical practice in the emerging institute “LIRYC” (headed by Pr M Haïssaguerre) dedicated to the study and treatment of electrical cardiac disorders.
The consortium of the “TACIT” project will include MR methodologists and image processing teams with established experience in real-time MR thermometry (acquisition and real-time processing) on mobile organs, world leader clinical team in cardiac RF ablation, Image guided Therapy SA (French local company dedicated to MR guided thermotherapies) and Surgivision/Siemens for MR compatible RF ablation devices MR integrated.