An architecture and implementation of real-time synthetic aperture compounding with SARUS

Synthetic aperture and compounding are imaging techniques for increasing the resolution and contrast of ultrasound images. Both techniques are computationally intensive, and combined they require approximately two orders of magnitude more lines to be beamformed per second compared to conventional B-mode imaging with similar frame rates. In this paper, an implementation of a system capable of synthetic aperture compound imaging in real-time producing more than 325 million complex beamformed samples per second is presented. This corresponds to synthetic aperture compound imaging at 13 frames per second with 64 emissions and 3 compound angles with 128 lines each. The beamformer is implemented in the SARUS research scanner which consists of 320 Virtex4 FPGAs and has 1024 independent transmit and receive channels. The beamformer is partitioned across 64 FPGAs and runs at 87.5 MHz while consuming 76% of the available logic resources in each FPGA. The beamformed images have resolution similar to offline processed images.