Conventional imaging approaches are based on geometry - focused beams, plane waves, diverging waves. Spatial encodings are rooted in information theory - Hadamard codes, for example. We are exploring new approaches that loosen these constraints to improve image quality and performance.

REFoCUS approach to beamforming

REFoCUS (Retrospective Encoding For Conventional Ultrasound Sequences) treats pulse sequencing as a linear encoding problem, making it possible to generalize decoding and synthetic aperture beamforming of a wide variety of imaging sequences. You can try it here:

Read more in our papers:

Results of encoding optimization

This approach has enabled us to explore further using advanced numerical methods to optimize transmit encodings for image quality improvements. We demonstrate that treating an imaging sequence as an underdetermined encoding and optimizing for various image quality parameters can produce images with expanded field of view and reduced off-axis scattering.

Proceedings: A Strategy for Synthetic Aperture Sequence Design using Numerical Optimization

Effect of motion on reconstructions

We also seek to understand the role that biological motion plays in this system. Synthetic aperture approaches generally assume a stationary target (or apply complicated motion correction). We demonstrate the relative sensitivity of different imaging sequences and combine more rapid and less motion sensitive approaches into a single mixed sequence.

Proceedings: Mixed Imaging Sequences for Improved Spatiotemporal Resolution in Cardiac Imaging