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Four papers accepted at FIMH15

The first authors of the accepted papers for the FIMH Conference are Sergio Sánchez, Bruno Paun, Marta Núñez and David Soto.

The FIMH is the International Conference on Functional Imaging and Modeling of the Heart. This biennial scientific event aims to integrate the research and development efforts in the fields of cardiovascular modeling and image analysis. The main goal is to encourage collaboration among scientists in signal and image processing, imaging, applied mathematics, biophysics, biomedical engineering, and experts in cardiology, radiology, biology and physiology.

Papers accepted

Characterization of Myocardial Velocities by Multiple Kernel Learning: Application to Heart Failure with Preserved Ejection Fraction 

Sergio Sanchez-Martinez, Nicolas Duchateau, Bart Bijnens, Tamás Erdei, Alan Fraser, and Gemma Piella

Abstract: This study aims at improving the characterization of myocardial velocities in the context of heart failure with preserved ejection fraction (HFPEF) by combining multiple descriptors. Using a multiple kernel learning (MKL) technique, it allows the combination of data of different natures towards the learning. The methodology is applied to 2D sequences from a stress echocardiography protocol from 33 subjects (21 healthy controls and 12 HFPEF subjects). The method provides a novel way to tackle the understanding of the HFPEF syndrome, in contrast with the diagnostic issues surrounding it in the current clinical practice. Notably, the results confirm that the characterization of the myocardial functional response to stress in this syndrome is improved by the joint analysis of multiple relevant features. 

Subject Independent Reference Frame for the Left Ventricular Detailed Cardiac Anatomy

Bruno Paun, Bart Bijnens, and Constantine Butakoff

Abstract: Mapping of surfaces to a parametric domain is a widely used tool in medical imaging for analysis and localization of injured tissue. By assigning the same coordinate values to specific anatomical landmarks, parametrization allows us putting into correspondence surfaces of anatomical shapes with inherently different geometry and facilitates integration of data acquired by different imaging modalities. In this paper we propose a method for subject independent anatomical parametrization of the left ventricular (LV) wall that includes trabeculations, papillary muscles and false tendons. The method relies on a disk parametrization of the LV smooth epicardium and mapping the interior of the ventricular cavity using ray casting. In this way we define a common reference frame whereupon any LV is mapped in a consistent way thus allowing for statistical analysis and comparisons between different patients.

Quantification of gaps in ablation lesions around the pulmonary veins in delayed enhancement MRI

Marta Núñez, Oscar Camara, Kawal Rhode, Bart Bijnens, Catalina Tobón-Gómez, Constantine Butakoff
Abstract: We propose a method for measuring the quality of pulmonary vein isolation in delayed enhancement MRI images for the patients that underwent atrial radiofrequency ablation. To that end we construct a graph from an anatomy independent representation of the atrium, where every node represents a scar lesion and the edges are the distances between the lesions. Subsequently we search for the shortest path in this graph. The total amount of gap between the scar lesions is measured as the fraction of the path’s length that passes through the healthy tissue.
We illustrate the proposed technique using pre-segmented atria from a freely available database and show that the proposed approach is able to measure the amount of gaps in the scar isolating the PV’s as well as provide a meaningful definition of the gap in cases where the scar lesions are patchy and not continuous.

Quantitative analysis of lead position vs. correction of electrical dyssynchrony in an experimental model of LBBB/CRT

David Soto-Iglesias , Nicolas Duchateau , Constantine Butakoff , David Andreu, Juan Fernández-Armenta, Bart Bijnens, Antonio Berruezo, Marta Sitges , and Oscar Camara.
Abstract: Cardiac resynchronization therapy (CRT) is a recommended treatment in patients with electrical dyssynchrony such as left bundle branch block (LBBB). The determination of the optimal leads position, and the quantification of the changes in electrical activation are two current major challenges. In this paper, we investigate these aspects through electroanatomical data from a controlled experimental protocol, which studied pigs with no structural disease under LBBB and CRT conditions. We propose to use a quasi-conformal mapping technique to standardize electroanatomical maps of endo- and epi-cardial walls of both ventricles to a common reference geometry, in which simple quantitative indices can be computed. Then, we investigate the relation between leads and simple surrogates of the recovery of the electrical activation based either on total activation times or on the spatial distribution of the patterns. Our methodology allows a better understanding of the complex electrical activation patterns in LBBB and CRT, and confirms hypotheses about the optimal leads position from previous studies.