The New Generation of the KIT 3D USCT

The first clinical studies with our current prototype, 3D USCT II, enabled us to identify the necessary improvements for transition of our method to clinical practice. The main goals are to improve the contrast of reflection and transmission tomography, and to optimize the coverage of the imaged breast by a new geometry of the transducer distribution. Furthermore, for cost-effective industrial mass production, a self-calibration method allows us to relax the precision of the positioning of the transducers to 0.1 mm. The readout of the transducer arrays is now carried out by an ASIC, developed for a more cost-effective design. The coupling of the measuring device to the patient was optimized to cover the full size of the breast up to the pectoral muscles. Finally, the data acquisition and readout time were reduced to 1.5 minutes each by new micro-TCA electronics and larger FPGAs

Localization of a Scatterer in 3D with a Single Measurement and Single Element Transducer

Conventionally an A-mode scan, a single measurement with a single element transducer, is only used to detect the depth of a reflector or scatterer. In this case, a single measurement reveals only one-dimensional information; the axial distance. However, if the number of scatterers in the ultrasonic field is sparse, it is possible to detect the location of the scatter in multiple spatial dimensions. In this study, we developed a method to find the location of a scatterer in 3-D with a single-element transducer and single measurement. The feasibility of the proposed method was verified in 2-D with experimental measurements

3-D Coherent Multi-Transducer Ultrasound Imaging with Sparse Spiral Arrays

Coherent multi-transducer ultrasound (CoMTUS) creates an extended effective aperture through the coherent combination of multiple arrays, which results in images with enhanced resolution, extended field-of-view, and higher sensitivity. The subwavelength localization accuracy of the multiple transducers required to coherently beamform the data is achieved by using the echoes backscattered from targeted points. In this study, CoMTUS is implemented and demonstrated for the first time in 3-D imaging using a pair of 256-element 2-D sparse spiral arrays, which keep the channel-count low and limit the amount of data to be processed. The imaging performance of the method was investigated using both simulations and phantom tests. The feasibility of free-hand operation is also experimentally demonstrated. Results show that, in comparison to a single dense array system using the same total number of active elements, the proposed CoMTUS system improves spatial resolution (up to 10 times) in the direction where both arrays are aligned, contrast-to-noise-ratio (CNR, up to 30%), and generalized CNR (up to 11%). Overall, CoMTUS shows narrower main lobe and higher contrast-to-noise-ratio, which results in an increased dynamic range and better target detectability.Comment: 10 pages, 6 figure

Experimental 3-D Ultrasound Imaging with 2-D Sparse Arrays using Focused and Diverging Waves

International audienceThree dimensional ultrasound (3-D US) imaging methods based on 2-D array probes are increasingly investigated. However, the experimental test of new 3-D US approaches is contrasted by the need of controlling very large numbers of probe elements. Although this problem may be overcome by the use of 2-D sparse arrays, just a few experimental results have so far corroborated the validity of this approach. In this paper, we experimentally compare the performance of a fully wired 1024-element (32 × 32) array, assumed as reference, to that of a 256-element random and of an " optimized " 2-D sparse array, in both focused and compounded diverging wave (DW) transmission modes. The experimental results in 3-D focused mode show that the resolution and contrast produced by the optimized sparse array are close to those of the full array while using 25% of elements. Furthermore, the experimental results in 3-D DW mode and 3-D focused mode are also compared for the first time and they show that both the contrast and the resolution performance are higher when using the 3-D DW at volume rates up to 90/second which represent a 36x speed up factor compared to the focused mode

3-D Motion Correction for Volumetric Super-Resolution Ultrasound Imaging

© 2018 IEEE. Motion during image acquisition can cause image degradation in all medical imaging modalities. This is particularly relevant in 2-D ultrasound imaging, since out-of-plane motion can only be compensated for movements smaller than elevational beamwidth of the transducer. Localization based super-resolution imaging creates even a more challenging motion correction task due to the requirement of a high number of acquisitions to form a single super-resolved frame. In this study, an extension of two-stage motion correction method is proposed for 3-D motion correction. Motion estimation was performed on high volumetric rate ultrasound acquisitions with a handheld probe. The capability of the proposed method was demonstrated with a 3-D microvascular flow simulation to compensate for handheld probe motion. Results showed that two-stage motion correction method reduced the average localization error from 136 to 18 μm