Preliminary in-vivo evaluation of synthetic aperture sequential beamformation using a multielement convex array

This paper presents a preliminary in-vivo study of synthetic aperture sequential beamforming (SASB) in comparison with conventional imaging. The advantage of SASB compared to conventional imaging, is the ability to obtain a more range independent point spread function, without any loss in lateral resolution or frame rate. The objective of this study is to evaluate whether SASB imaging is feasible in-vivo and whether the image quality obtained is comparable with traditional scanned imaging in terms of penetration depth, spatial resolution, contrast, and unwanted artifacts. Acquisition was performed using a ProFocus ultrasound scanner and a 5 MHz convex array transducer. First stage beamformed SASB radio frequency (RF) data were acquired using a transmit and receive focal depth of 70 mm and 63-element sub-apertures. Subsequently the data were off-line processed to generate second stage SASB RF data. For conventional imaging, beamformed RF data was acquired using 63-element sub-apertures in transmit with a focal depth of 105 mm, in receive an expanding aperture using dynamic focusing with a F-number of 0.8 was used. Both modalities used the same standard manufacturer specified pulse. Conventional and SASB RF data were acquired interleaved, ensuring that the exact same anatomical location was scanned. RF data were recorded in real time and processed off-line to generate image sequences. Two male volunteers were scanned abdominally resulting in 34 image sequence pairs. Evaluation of image quality and penetration was performed by five medical doctors. Results showed no significantly (p = 0.98) increase nor decrease in penetration using SASB. Overall image quality was highly significantly (p < 0.001) increased. Results show that in-vivo ultrasound imaging using SASB is feasible for abdominal imaging without severe motion artifacts.