Hundreds of millions of ultrasound (US) exams are performed each year worldwide. Typical limitations of conventional US imaging include operator dependence, limited field of view, limited contrast, and diffraction- limited resolution. Volumetric imaging has the potential to create an operator-independent acquisition protocol, and ultrafast US acquisition has opened new opportunities to address field-of-view and contrast issues. Our extended aperture approach applied here addresses spatial resolution limitations as well. With high resolution, real-time imaging capabilities and the lack of ionizing radiation, US has great promise for imaging pediatric patients; in particular, for children under 3 who cannot be imaged with MRI or CT without anesthesia, the development of a high-resolution volumetric US scanner would be transformative. In particular, we set out to image the pediatric liver and kidney within ~0.1 second, which requires a technological leap. New ASIC switch matrices will enable high speed acquisition and GPU-based partial beam formation enables the visualization of the 3D data. Reconstruction of the 3D vascular structure facilitates image-based recognition of the anatomical location of a lesion. Ultrafast SVD Doppler imaging allows the visualization of very small blood vessels with blood flow velocities as low as 4 mm/s. Abdominal pain is very common in children and US is frequently used to determine the cause. Accurate volumetric measurements of the kidney are problematic due to patient motion and operator-dependent scanning. Assaying the liver and abdomen, particularly in the context of trauma are similarly important. Thus, we seek to create this real-time imaging tool with resolution that exceeds CT and MR but without the need for anesthesia or radiation. Using 1024 active system channels with integrated GPU beamformers, we will create 2 transducers to span the needs of children for this technology, with spatial resolution at 5 cm (~300 (azimuth) x 600 (elevation) x 300 (depth) µm) that should exceed that offered by MRI or CT by several fold. The array will be realized using tiled modules that can be switched in a mode-dependent fashion to accomplish B-mode imaging, color Doppler and contrast imaging. Over the past four years, Stanford University and the University of Southern California have designed an adult extended-aperture abdominal- imaging system, and demonstrated the improved spatial resolution, field of view and contrast that can be achieved. We exploit these tools here to develop a dedicated pediatric volumetric scanner. Our aims to accomplish this are to 1) create and integrate acoustic/electronic transducers to implement signal buffering and multiplexing; and 2) develop volumetric software and conduct pediatric imaging studies as a proof of concept. We will develop the software and systems, test the system components on adult volunteers and phantoms, and develop 3D volumetric processing. We will image a cohort of pediatric patients spanning 3D kidney volumetric mapping, detection and mapping of previously detected liver lesions. In each case, MRI will provide the gold standard.

Narrative We will develop an ultrafast and very-high-resolution system for volumetric pediatric imaging. The system will facilitate imaging of children who are too young to be imaged with MRI or CT without anesthesia and will provide resolution on the order of hundreds of microns.