Program Information
Cardiac Fiber Imaging Using High-Frequency Ultrasound in Animal Models
B Fei*, X Qin , S Wang , M Shen , M Wagner , X Zhang , Emory University, Atlanta, GA
Presentations
TU-F-12A-7 Tuesday 4:30PM - 6:00PM Room: 12APurpose: Cardiac fibers directly affect the mechanical and electrophysiological properties of the heart. The objective of this study is to explore high-frequency ultrasound imaging for measuring cardiac fiber orientation in an animal model.
Methods: An ex vivo heart model was used in this study. The hearts of male rats were excised, perfused, fixed, and embedded in agar phantoms for two imaging procedures. First, the hearts were first imaged by the Vevo 2100 ultrasound system with a 30 MHz transducer. Second, the hearts were then scanned using a Biospec 7 T MRI system for high-resolution MRI and diffusion tensor imaging (DTI). The geometry of the heart extracted from the MRI is registered with the 3D ultrasound using deformable registration. After registration, deformation fields between both geometries from MRI and ultrasound are obtained. The cardiac fiber orientations imaged by DTI are mapped to ultrasound volumes based on the extracted deformation fields. The registration between 3D ultrasound and MRI of different hearts, e.g. one from the atlas, was further tested. The DTI fiber orientation from the atlas was then mapped to the ultrasound image of a different heart. By this way, we provide a DTI atlas based framework to estimate cardiac fiber orientations from 3D ultrasound images.
Results: After MRI/ultrasound image registration, the Dice similarity scores were more than 90% and the corresponding target errors were less than 0.25 mm. For the atlas-based method, the evaluation results demonstrated the feasibility of determining cardiac fiber orientations from 3D ultrasound.
Conclusion: An atlas-based fiber orientation estimation method was proposed and evaluated for the extraction of cardiac fiber orientation in an animal model. This method and its further improvements in vivo could contribute to understand the cardiac mechanism and help the diagnosis and therapy of heart disease.
Funding Support, Disclosures, and Conflict of Interest: This research is supported in part by NIH grants (R01CA156775 and R21CA176684), Georgia Research Alliance Distinguished Scientists Award, and the Emory Molecular and Translational Imaging Center (NIH P50CA128301).
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