Evaluation of Large-Aperture Imaging Through the ex Vivo Human Abdominal Wall.

Current clinical abdominal imaging arrays are designed to maximize angular field of view rather than the extent of the coherent aperture. We illustrate, in ex vivo experiments, the use of a large effective aperture to perform high-resolution imaging, even in the presence of abdominal wall-induced acoustic clutter and aberration. Point and lesion phantom targets were imaged through a water path and through three excised cadaver abdominal walls to create different clinically relevant clutter effects with matched imaging targets. A 7.36-cm effective aperture was used to image the targets at a depth of 6.4 cm, and image quality metrics were measured over a range of aperture sizes using synthetic aperture techniques. In all three cases, although degradation compared with the control was observed, lateral resolution improved with increasing aperture size without loss of contrast. Spatial compounding of the large-aperture data drastically improved lesion detectability and produced contrast-to-noise ratio improvements of 83%-106% compared with the large coherent aperture. These studies indicate the need for the development of large arrays for high-resolution abdominal diagnostic imaging.