RESUMO
A novel B-Spline based approach to phase unwrapping in tagged magnetic resonance images is proposed for cardiac motion tracking. A bicubic B-spline surface is used to model the absolute phase. The phase unwrapping problem is formulated as a mixed integer optimization problem that minimizes the sum of the difference between the spatial gradients of absolute and wrapped phases, and the difference between the rewrapped and wrapped phases. In contrast to the existing techniques for motion tracking, the proposed approach can overcome the limitation of interframe half-tag displacement and increase the robustness of motion tracking. The article further presents a hybrid harmonic phase imaging-B-spline method to take the advantage of the harmonic phase imaging method for small motion and the efficiency of the B-Spline approach for large motion. The proposed approach has been successively applied to a full set of cardiac MRI scans in both long and short axis slices with superior performance when compared with the harmonic phase imaging and quality guided path-following methods.
Assuntos
Ventrículos do Coração/anatomia & histologia , Interpretação de Imagem Assistida por Computador/métodos , Imagem Cinética por Ressonância Magnética/métodos , Movimento/fisiologia , Contração Miocárdica/fisiologia , Reconhecimento Automatizado de Padrão/métodos , Função Ventricular Esquerda/fisiologia , Algoritmos , Humanos , Aumento da Imagem/métodos , Imageamento Tridimensional/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Técnica de SubtraçãoRESUMO
A VR simulator provides low-cost, realistic training for intracardiac techniques for determining the heart's mechanical and electrical activities. A geometric method models interaction between a catheter and the heart wall. Boundary-enhanced voxelization accelerates detection of catheter-heart interaction. A tactile interface incorporates a VR catheter unit to track the catheter's movement.
