Tissue characterization from myocardial perfusion and autonomic innervation using MRI and SPECT images in chagas disease

Chagas disease is of major clinical relevance, with high incidence.The relation between the myocardial tissue damage, myocardial perfusion and defects in the autonomic innervations is poorly understood. This work proposes the development and application of image analysis methods capable of providing an integrated visualization and analysis of tissue injuries through magnetic resonance imaging (MRI), autonomic innervations and myocardial perfusion, available through photon emission tomography (SPECT). This paper describes and evaluates a method for tissue characterization and quantication. The proposed method is based on segmentation of MRI and registration between MRI images and SPECT images using metaiodobenzylguanidine (MIBG) and 99Tc (m)-methoxy-isobutyl-isonitrile (MIBI). To perform the segmentation of myocardium, we used Geodesic Active Contour. Fibrosis segmentation in MRI images was performed based on the algorithm of maximum Tsallis entropy. Nonrigid registrations was performed based on B-Spline method. Initially, the registration was made between SPECT images using 99Tc (m)-MIBI and MIBG. Then MRI volumes were registered with SPECT images. It is possible to observe regions of brosis and with absence or low synaptic activity comparatively to myocardial perfusion. The relationship of regions of fibrosis and regions with absence of synaptic activity was obtained by Kendall correlation, which provided a correlation coefficient of 0.8788. Thus, the developed tool provides an integrated analysis of information contributing to a better understanding of the relationship between myocardial tissue damage and autonomic innervations injuries caused by Chagas disease.