Forming Large Effective Ultrasound Arrays Using the Swept Synthetic Aperture Technique

Ultrasound image quality is intrinsically linked to the hardware used to collect image data. For deep abdominal imaging, diffraction-limited resolution prevents the detection of small targets such as cancerous lesions. Larger ultrasound arrays produce finer lateral image resolution and improved image quality. We introduced a method called "swept synthetic aperture" (SSA) imaging to synthetically create large effective arrays with reduced complexity of both transducer and scanner hardware. A commercial 2-D transducer array and ultrasound scanner were used to form a large effective aperture. Array position and orientation were carefully prescribed throughout a sweep of the transducer using mechanical fixtures to rigidly control the motion. Calibration of the mechanical fixture was measured using a point target phantom and applied in post-processing. Improvements in resolution and contrast as functions of aperture size were measured from point and lesion target phantoms, respectively. SSA imaging presents a technique to both evaluate the performance of large array designs in the presence of clutter-inducing body wall targets and achieve high-quality imaging from reduced-complexity ultrasound hardware.