Dr. Gerardo I. Sanchez-Ortiz Profile

Dr. Gerardo I. Sanchez-Ortiz

Research Associate at Imperial College London

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Publications (2)

Proceedings Article | 30 April 2004 Paper

Detecting regional changes in myocardial contraction patterns using MRI

Gerardo Sanchez-Ortiz, Raghavendra Chandrashekara, Kawal Rhode, Reza Razavi, Derek Hill, Daniel Rueckert

Proceedings Volume 5369, (2004) https://doi.org/10.1117/12.536090

KEYWORDS: Image segmentation, Magnetic resonance imaging, Motion measurement, Image registration, Image acquisition, Motion models, 3D image processing, Heart, X-ray imaging, X-rays

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Proceedings Article | 30 April 2004 Paper

XMR guided cardiac electrophysiology study and radio frequency ablation

Kawal Rhode, Maxime Sermesant, Sanjeet Hegde, Gerardo Sanchez-Ortiz, Daniel Rueckert, Reza Razavi, Derek Hill

Proceedings Volume 5369, (2004) https://doi.org/10.1117/12.535103

KEYWORDS: X-rays, Magnetic resonance imaging, X-ray imaging, Image registration, Motion models, Heart, Image segmentation, Electrodes, Radiofrequency ablation, Data modeling

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XMR systems are a new type of interventional facility in which patients can be rapidly transferred between x-ray and MR systems on a floating table. We have previously developed a technique to register MR and x-ray images obtained from such systems. We are carrying out a program of XMR guided cardiac electrophysiology study (EPS) and radio frequency ablation (RFA). The aim of our work was to apply our registration technology to XMR guided EPS/RFA in order to integrate anatomical, electrophysiological and motion information. This would assist in guidance and allow us to validate and refine electromechanical models. Registration of the imaging modalities was achieved by a combination of system calibration and real-time optical tracking. Patients were initially imaged using MR imaging. An SSFP volume scan of the heart was acquired for anatomical information, followed by tagged scans for motion information. The patients were then transferred to the x-ray system. Tracked biplane x-ray images were acquired while electrical measurements were made from catheters placed in the heart. The relationship between the MR and x-ray images was determined. The MR volume scan of the heart was segmented and the tagged scans were analysed using a non-rigid registration algorithm to compute motion. The position of catheters was reconstructed within the MR cardiac anatomy. The anatomical, electrophysiological, and motion information were displayed in the same coordinate system. Simulations of electrical depolarisation and contraction were performed using electromechanical models of the myocardium. We present results for 2 initial cases. For patient 1, a contact mapping system was used for the EPS and for patient 2, a non-contact mapping system was used. Our XMR registration technique allows the integration of anatomical, electrophysiological, and motion information for patients undergoing EPS/RFA. This integrated approach has assisted in interventional guidance and has been used to validate electromechanical models of the myocardium.

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