Adaptive imaging in the breast
Various adaptive imaging methods have been proposed to compensate for the image degradation caused by the non-uniform acoustic velocity in soft tissues. Most adaptive imaging methods employ measurements of echo arrival times at the receive array to modify the timing of signals transmitted and received and form the 'corrected' image. In breast ultrasound imaging, improved image contrast and resolution would improve differential diagnosis of solid lesions and cyst, of benign and malignant lesions, and in the detection of microcalcifications. We report clinical measurements of arrival time profiles over large tissue regions in the breast using a 1.75D array. We used microcalcifications as targets of opportunity for these measurements. Arrival time profiles were measured using both fundamental and harmonic echoes and were employed to form 'corrected' B-mode images. We report large artifacts in arrival time profiles measured from regions of soft tissue containing specular interfaces, bright off-axis targets, or off-axis clutter. The effects of the artifacts were often reduced in harmonic echoes obtained from matched locations. Arrival time profiles apparently uncorrupted by target scattering artifacts were generally low magnitude and yielded improved image brightness.
