Three-dimensional ultrasound vector-flow imaging for improved diagnosis and understanding of cardiac disease

The heart is an extraordinary pump that transports blood to the body, beat after beat, steadily throughout a lifetime. Unfortunately, negative developments can occur to disturb this ability, for instance related to congenital heart disease in very early stages of life, or due to age-related developments such as elevated blood pressure (hypertension) or a blocking of blood vessels supplying the heart itself (atherosclerosis). If not detected and treated in time such conditions will inevitably lead to heart failure, currently the leading causes of death in the Western world. One of the most important tools for detecting and diagnosing heart disease is medical ultrasound imaging. High-frequency sound waves emitted into the body are reflected differently depending on type of tissue (muscle, fat, blood), and from these echoes an image is formed. Ultrasound is safe and can be used bedside. It is the main imaging tool for cardiologist in hospitals around the world. The blood flow movement in the heart is strongly coupled to its function, but detailed knowledge of blood flow patterns and heart disease is currently lacking. Our main hypothesis is that these blood flow patterns (for instance vortex flow) contains important clinical information related to heart disease. The problem is; there is currently no bedside imaging tool that can supply this information. In this project we will therefore develop ultrasound imaging technology capable of measuring three-dimensional blood flow patterns, called vector-flow imaging. This technology will be used to establish relationships between heart disease and flow patterns in both children and adults. The outcome of this project will be new knowledge of heart disease, technological innovation in form of new ultrasound imaging techniques, and new diagnostic information to be used in the future clinic. A technique for ultrasound measurement of blood flow patterns in the heart of newborns and children has been developed and applied in patients with and without congenital heart disease, in Trondheim and a larger children's hospital in Toronto. Results showed that the new imaging technique could portray the complex flow patterns with substantially improved accuracy and detail compared to conventional methods. Further, a new visualisation method was developed which is substantially more intuitive, and which we hope can helps to reduce misinterpretation by the medical doctors, as well as make it easier to convey the complex information in the images to the parents. Data from the first study is currently being analyzed, and preliminary results indicate that 1) the new method can be used with high feasibility, and 2) the method provides new information about the blood flow patterns in the heart. Detailed analysis will now follow to find map the usefulness of the approach. The technique was extended to work in 3D imaging, and recently in vivo 3D cardiac flow patterns was demonstrated using a clinical scanner, paving the way for larger clinical studies for investigating the relation between detailed cardiac flow patterns and cardiac disease. We have further developed the approach to work with fetal imaging, and a study looking at healthy fetuses at different time points from week 20 is ongoing. Preliminary results have shown detailed flow images of fetal circulation not previously achieved. We are first mapping the feasibility of this approach, and will further target specific challenges in congenital heart disease through further clinical studies. Our industrial partner GE Vingmed was inspired by our work and have implemented our method which was recently launched on their premier ultrasound scanner (Vivid E95). The method is now available for use in hospitals across the world. In summary, we have developed a new ultrasound imaging modality capable of mapping detailed blood flow patterns in two- and three-dimensional images. We have observed that the method provides unique data which we hope contains new clinical information about heart disease. Our on-going and future clinical studies will reveal this potential. We are today a larger team of engineers and medical doctors who wants to take this project further.

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Cardiovascular disease is currently the leading cause of death in the Western world, and research resulting in new knowledge that may help detect and prevent such disease is considered of high value. One of the most important tools for the diagnosis of ca rdiovascular disease is medical ultrasound imaging. Our main goal is to develop a new ultrasound imaging modality capable of resolving three-dimensional (3D) vector-flow velocities in the heart during patient examinations. That is, measuring all three com ponents of the blood velocity vector, where current techniques are based on a limited one-dimensional measurement. Our clinical hypothesis is that three-dimensional blood vector-flow patterns contain information useful for the diagnosis of cardiac disease , information that is currently not available during bedside diagnosis. This is considered a challenging task that will involve next-generation ultrasound imaging technology. We will further use this technique to study the complex relationship between car diac blood flow patterns and cardiac disease. The project will involve: 1) technical research and development of real-time 3D vector-flow imaging for cardiac applications, 2) in vivo small animal experiments for basic research into the relation between 3 D flow fields and cardiac disease, 3) biomechanical modelling and simulation for improved understanding of flow in congenital heart disease and associated surgical treatment (Fontan circulation), and 4) patient trials and method validation in pediatric an d adult cardiology towards 4D phase-contrast MRI. It is a cross-disciplinary project that includes national and international collaboration partners who will contribute with expert knowledge in their respective fields. When successful, the outcome of th is project will be basic science in form of new pathophysiological knowledge, technological innovation in form of a new ultrasound imaging modality, and new diagnostic information to be used in the future clinic.