In Vivo Evaluation of Synthetic Aperture Sequential Beamforming

Medical Imaging 2015: Ultrasonic Imaging and Tomography

Martins³

et al. 2015

Time gain compensation (TGC) is essential to ensure the optimal image quality of the clinical ultrasound scans. When large fluid collections are present within the scan plane, the attenuation distribution is changed drastically and TGC compensation becomes challenging. This paper presents an automated hierarchical TGC (AHTGC) algorithm that accurately adapts to the large attenuation variation between different types of tissues and structures. The algorithm relies on estimates of tissue attenuation, scattering strength, and noise level to gain a more quantitative understanding of the underlying tissue and the ultrasound signal strength. The proposed algorithm was applied to a set of 44 in vivo abdominal movie sequences each containing 15 frames. Matching pairs of in vivo sequences, unprocessed and processed with the proposed AHTGC were visualized side by side and evaluated by two radiologists in terms of image quality. Wilcoxon signed-rank test was used to evaluate whether radiologists preferred the processed sequences or the unprocessed data. The results indicate that the average visual analogue scale (VAS) is positive ( p-value: 2.34 × 10 −13 ) and estimated to be 1.01 (95% CI: 0.85; 1.16) favoring the processed data with the proposed AHTGC algorithm.

Section: Methodsmentioning

confidence: 99%

Section: -3mentioning

confidence: 98%

Automated hierarchical time gain compensation forin-vivoultrasound imaging

Moshavegh

Medical Imaging 2015: Ultrasonic Imaging and Tomography

Martins³

et al. 2015

“…10 The method has been clinically demonstrated to be equally good compared to conventional dynamic receive focusing, 11 with the advantages of reduced system requirements and effective reduction of the data transfer rate between the probe and the processing unit. A virtual source (VS) is emulated in front of the transducer by means of a focused emission.…”

Section: Synthetic Aperture Sequential Beamformingmentioning

confidence: 99%

“…The system is based on Synthetic Aperture Sequential Beamforming (SASB). 10 The approach has been demonstrated in the clinic to provide images equally good compared to conventional dynamic receive focusing, 11 while reducing the system requirements due to the implementation of a static-focus beamformer in the transducer handle. Only a single beamformed line per emission needs to be transmitted to the central unit, and the transfer rate is reduced by a factor M .…”

Section: Introductionmentioning

confidence: 99%

Analog gradient beamformer for a wireless ultrasound scanner

Ianni

Bagge³

et al. 2016

SPIE Proceedings

Self Cite

This paper presents a novel beamformer architecture for a low-cost receiver front-end, and investigates if the image quality can be maintained. The system is oriented to the development of a hand-held wireless ultrasound probe based on Synthetic Aperture Sequential Beamforming, and has the advantage of effectively reducing circuit complexity and power dissipation. The array of transducers is divided into sub-apertures, in which the signals from the single channels are aligned through a network of cascaded gradient delays, and summed in the analog domain before A/D conversion. The delay values are quantized to simplify the shifting unit, and a single A/D converter is needed for each sub-aperture yielding a compact, low-power architecture that can be integrated in a single chip. A simulation study was performed using a 3.75 MHz convex array, and the point spread function (PSF) for different configurations was evaluated in terms of lateral full-width-at-half-maximum (FWHM) and −20 dB cystic resolution (CR). Several setups were simulated varying the sub-aperture size N and the quantization step, and design constraints were obtained comparing the PSF to that of an ideal non-quantized system. The PSF is shown for N = 32 with a quantization step of 12 ns. For this configuration, the FWHM is degraded by 0.25% and the CR is 8.70% lower compared to the ideal situation. The results demonstrate that the gradient beamformer provides an adequate image quality, and open the way to a fully-integrated chip for a compact, low-cost, wireless ultrasound probe.

“…The second beamformer recombines a set of emissions to create the final high-resolution image (Hemmsen et al 2012a;Kortbek et al 2013). Previous studies have evaluated the image quality of SASB against conventional dynamic receive focusing (DRF) and reported equally good image quality, indicating that SASB is applicable to medical imaging , 2012b, Hansen et al 2014. SASB can generate an acoustic field intense enough to create harmonics for THI, and it has been suggested that these techniques be combined to improve the image quality of SASB even further.…”

Section: Introductionmentioning

confidence: 99%

Clinical Evaluation of Synthetic Aperture Harmonic Imaging for Scanning Focal Malignant Liver Lesions

Brandt

Ultrasound in Medicine & Biology

Hansen

et al. 2015

Self Cite

Abstract-The purpose of the study was to perform a clinical comparison of synthetic aperture sequential beamforming tissue harmonic imaging (SASB-THI) sequences with a conventional imaging technique, dynamic receive focusing with THI (DRF-THI). Both techniques used pulse inversion and were recorded interleaved using a commercial ultrasound system (UltraView 800, BK Medical, Herlev, Denmark). Thirty-one patients with malignant focal liver lesions (confirmed by biopsy or computed tomography/magnetic resonance) were scanned. Detection of malignant focal liver lesions and preference of image quality were evaluated blinded off-line by eight radiologists. In total, 2,032 evaluations of 127 image sequences were completed. The sensitivity (77% SASB-THI, 76% DRF-THI, p 5 0.54) and specificity (71% SASB-THI, 72% DRF-THI, p 5 0.67) of detection of liver lesions and the evaluation of image quality (p 5 0.63) did not differ between SASB-THI and DRF-THI. This study indicates the ability of SASB-THI in a true clinical setting.