High channel count ultrasound beamformer system with external multiplexer support for ultrafast 3D/4D ultrasound

We present the newest application specific version of our beamformer platform “DiPhAS” that provides 256 parallel channels both for generation of ultrasound signals as well as digitalization of returned echos. Using ultrasound transducers with lots of elements requires high channel count electronics. Applications for such systems range from functional ultrafast imaging using high element count linear array transducers for imaging of a large field of view to real time volumetric imaging with matrix array transducers. To perform volumetric transmit beamforming with matrix transducers, lots of these matrix elements have to be controlled individually. Furthermore, many elements need to be excited in order to compensate for the small active element size and provide a sufficient overall active footprint to generate enough acoustic power for imaging with adequate SNR. The system is set up based on our platform concept with the common ultrasound research device components: mainboard, power supply, application-specific new front ends integrating 16 channels on each PCB and device software. Using 16 front ends results in a total channel count of 256. The new front ends are based on our existing 8 channel front end technology and share the same concepts with doubled channel count for both transmission and reception. The system generates transmit sequences with voltages up to 150 Vpp and digitizes with a sampling rate of up to 80 MHz. The beamformer implements the control for additional external multiplexers in the transducer probe. This has been tested with an external transducer matrix array and can be used to connect to our custom 1024 elements matrix array (32×32 elements) with a 1:4 multiplexer integrated into the probe head. Received data can be accessed as single element channel data of all 256 channels in parallel and transferred to a PC via PCI-Express. Beamforming can be done on a massively parallel computing graphics processor (GPU). The used software includes standard applications for measurements and interfaces for Matlab, C++ and C#. It is used to process, analyze and visualize data from the beamformer. This system will be scalable to an even higher channel count by connecting several beamformers to a single PC using multiple PCI-Express connections and additional synchronization over all single beamformer electronics. It is the basis of our 3D/4D ultrasound research system connected to our matrix arrays developed in-house

Ultrasonography-based motion tracking for MRgFUS

Non-invasive treatment of moving organs like liver and kidney with high intensity focused ultrasound (HIFU/FUS) is challenging. The highly precise HIFU ablation requires real-time knowledge of tumor position with mm precision. The aim of this work was to build up a magnetic resonance imaging compatible tracking device using diagnostic ultrasound imaging for MR guided FUS (MRgFUS). The hardware of the developed US-tracking system comprises the ultrasound beam former with a screen directly placed in front of the MR-magnet, a linear and a special ultrasound tracking probe. The tracking probe (2x64 element phased array) can acquire two perpendicularly oriented US-image planes for quasi 3D tracking. The US-data are sent to a workstation in the console room of the MRI scanner which controls the whole tracking device. The tracking software (Sonoplan II) analyzes the ultrasound image stream and calculates the actual position of pre-defined contours. Beside the 2D-translation, the tracking algorithm analyzes the rotation as well as the 2D scaling of the contour. The developed US-tracking system proved MR-compatibility in 1.5 and 3 T MR-systems and enabled simultaneous MR-and US-imaging and motion tracking. In the next step, the tracking system will be combined with an MRgFUS unit