High resolution Ultrasound Transmission Tomography

• Applicants: Professor Dr. Jürgen Hesser; Dr. Torsten Hopp
• Subject Area: Medical Physics, Biomedical Technology
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 283966455

The aim of this proposal is to provide a new method for early breast cancer diagnosis: high resolution three-dimensional ultrasound transmission tomography. By imaging the quantitative tissue parameters sound speed and attenuation, it enables new insights in breast cancer diagnosis. The current standard image reconstruction for transmission tomography uses a ray-based algebraic reconstruction approach, which limits the resolution considerably. This restricts the applicability of the method as the detection of small tumors is not possible. In this project, we overcome these limitations by a new iterative reconstruction method based on a more accurate forward modeling with the paraxial approximation. The substantially higher computational demand is tackled by most recent and sophisticated optimization strategies. The objective is to reach one order of magnitude higher resolution while reducing the number of iterations to solve the ill-posed inverse problem by one order of magnitude compared to the current methods. The reduction of iterations together with an efficient implementation on parallel infrastructures like a multi-GPU system allows the reconstruction of high resolution three-dimensional volumes in a clinically relevant time for diagnosis at the same day. The development of a high resolution transmission tomography method is essential for ultrasound applications in medicine. The developed method will be applied in this project to an innovative new imaging modality, "3D Ultrasound Computer Tomography" (USCT) for early breast cancer diagnosis. In previous work, the Karlsruhe Institute of Technology (KIT) developed, built and characterized the world's first 3D USCT. With the current ray-based reconstruction method, the resolution of transmission tomography in 3D USCT is limited to max. 12mm. Establishing the new reconstruction method, the resolution increase of an order of magnitude potentially allows 3D USCT to detect cancers of a size below 5mm, which increases the chance of survival for concerned patients dramatically. By combining the expertise in ultrasound system development (KIT) and ill-posed inverse problems (University Heidelberg) we are prepared to address this research problem. The developed method will be evaluated by simulated, phantom and in-vivo data. This lays the foundation for following clinical studies to evaluate the sensitivity and specificity of the method. Establishing the high resolution transmission tomography reconstruction would present a major breakthrough. It potentially makes 3D USCT a highly desirable and economic modality for clarification of suspicious diagnoses or - in future - even as screening modality for early breast cancer detection.

• DFG Programme: Research Grants