Large aperture and wideband modular ultrasound arrays for the diagnosis of liver cancer

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Our project has two fundamental goals: 1) develop modular large aperture, high channel count arrays with associated electronics and make these modules widely available to the academic community, and 2) use these arrays to improve abdominal ultrasound (US) for the diagnosis of liver cancer, particularly for difficult to image patients. The overall 5-year relative survival rate for patients with primary liver cancer is 16%. In many cases, imaging is used to monitor liver disease resulting from viral infections or cirrhosis and to detect a transition to malignancy, and ultrasound is the only recommended method for screening such patients at risk for cancer. Yet, in patients with an abdominal wall thickness greater than 2.5 cm, only 33% of lesions were detected. More than 2/3 of Americans are now overweight or obese and larger channel count arrays and larger array footprints will improve imaging within this population as well as improving the detection of small lesions in the general population. Our approach addresses improved resolution (large aperture and bandwidth), sensitivity (single crystal transducers), high frame rate for super-resolution imaging (hundreds of frame/sec feasible), yield (array is composed of high yield modules), and image contrast (new switching capabilities enable new beamformation methods). Lateral US resolution is inversely proportional to the transducer aperture and consequently, improved resolution requires an increased number of transducer elements and electronic channels as well as advanced beam formation methods. Even in the presence of aberrating tissues we show that the contrast achieved from an extended aperture facilitates the visualization of small structures. We propose to create PIN- PMN-PT array modules of dimension 16 elements (azimuth) by 32 elements (elevation) which will be combined to form large arrays. The user selectable ASIC matrices provide the opportunity to select: 512 elements from within a single module, to combine mirrored elements in elevation or to combine neighboring elements in azimuth or elevation. As a result, 4096 elements within the large aperture array can simultaneously be addressed from a programmable scanner. Our specific aims span the development of the large area array technology, the integration of that technology to create large area concave arrays adapted for abdominal imaging and the use of the resulting technology to detect liver cancer. Preliminary work has resulted in the fabrication of prototype array and ASIC modules. The UC Davis team has been one of the first to produce multi-frequency arrays; USC has pioneered high frequency arrays and is currently home to Wodnicki (20 years of experience in ultrasound ASIC development at GE) and will collaborate with us on the development of high channel count arrays; Duke University has pioneered the development of strategies to use large apertures; Verasonics is the leading manufacturer of programmable ultrasound systems and will work with us to develop the technology and to distribute it to the ultrasound community. This unique team will develop the technology, evaluate its use in a human study and will disseminate the technology.