Assessment of the potential of beamforming for needle enhancement in punctures

In sonography the visibility of a needle becomes poor for deep puncture targets because the angle of incidence of the ultrasound wave increases. In [1] we showed with simulations and measurements that despite large puncture angles an unexpectedly good needle visibility in some image sectors can be generally explained by resonant scattering modes of the needle. As a first step to assess the potential of needle enhancement by a beamformer adapted to the needle specific signals, we investigate the RF signals scattered from the needle, which are received at the transducer's single elements. We show that these RF signals arrive earlier at the elements than assumed for the conventional beamforming. This effect leads to artefacts in the B-mode images. But, the more important fact is that considerable energy scattered from the needle is not used for its detection and imaging. With a rough estimate we show that a needle signal enhancement of up to 26 dB depending on the puncture angle could be possible.