Assessment of Myofiber Orientation in High Resolution Phase-Contrast CT Images.

Complex helical organization of cardiac fibers is one of the key factors for efficient beat-to-beat contraction and electrical impulse propagation. Complete understanding of this (inter-individual) configuration is limited by image acquisition and analysis constraints. Consequently, extensive quantification of myofiber orientation and remodeling within diverse cases is still lacking. With its high resolution and contrast, synchrotron-based phase-contrast X-ray imaging offers potential for assessing this information. Although it recently gained increased attention for biomedical purposes, only few cardiac applications were presented to this date. In this paper, we used synchrotron-based acquisitions of a healthy fetal rabbit heart and implemented a structure tensor method for estimating fiber orientation. For comparison, we generated the common rule-based model, simulating fiber angles distribution for the given geometry. Although we find similar fiber angle transmural courses compared to the theoretical, high-resolution imaging and analysis show that the myocardium in an individual is more complex than often assumed.