Since the discovery of piezoelectricity in 1880 by Pierre Curie, ultrasonic waves could be deliberately transmitted, and their echoes detected by the same element. In 1940, ultrasonic imaging (Reflectoscopy) was first introduced for industrial use, and later for medical use in 1941[1]. Many advancements were developed for this modality, such as Doppler-ultrasonography for speed-of-flow measurements, High-Intensity Focused Ultrasound (HIFU) for therapeutic lesioning, Elastography, and more.

Resolution improvement in ultrasound imaging

Ultrasound imaging resolution is limited by its relatively large wavelengths. Medium inhomogeneities also contribute to resolution degradation, as ultrasonic image reconstruction (or focusing, as done in HIFU[2]) is performed under the assumption of a non-varying speed-of-sound in the medium. However, the speed-of-sound may vary significantly in many practical imaging scenarios (such as in biological tissue).

We are working to implement super-resolution methods from optical imaging in ultrasound imaging modalities to overcome the system's acoustic diffraction limit. By adapting these techniques, we aim to achieve higher-resolution imaging in ultrasound-based applications.

Our work focuses on the analysis and adaptation of the pixel-reassignment (aka Image-Scanning-Microscopy, ISM) method onto the acoustic regime.
This approach was adapted from confocal fluorescence microscopy to ultrasound imaging, developing Ultrasound Pixel Reassignment (UPR). This technique computationally refocuses signals of traditional ultrasound scans, breaking the SNR-resolution tradeoff and achieving a 25% resolution boost and a 3 dB signal-to-noise ratio (SNR) improvement without requiring hardware modifications.

Additionally, we have provided a theoretical foundation for coherent-imaging ISM, drawing connections between it, synthetic-aperture radar (SAR), and oblique-illumination microscopy. By analyzing ISM in k-space, we have demonstrated that it can theoretically be performed using a single detector, while maintaining its resolution and SNR benefits.
Overall, our work bridges imaging modalities - medical ultrasound, optical microscopy, and RF imaging, enabling increased performance and expanding the potential applications of these methods.  

Previous group works:
Sommer, Tal I., and Ori Katz.“Pixel-reassignment in ultrasound imaging”. Applied Physics Letters 119.12 (2021): , 119, 12, 123701.
Sommer, Tal I., Gil Weinberg, Ori Katz; "K-space interpretation of image-scanning-microscopy". Applied Physics Letters 122.14 (2023): 122, 14, 141106.