Space Variant Ultrasound Frequency Compounding Based on Noise Characteristics

Erez, Yael; Schechner, Yoav Y.; Adam, Dan

doi:10.1016/j.ultrasmedbio.2007.11.012

Cited by 12 publications

(7 citation statements)

References 13 publications

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“…Speckle reduction has been widely studied in medical images. Filtering compounding [3,22,23] and incoherent compounding [24,25,26,27,28,29,30] methods are two main approaches for speckle reduction. Novel approaches such as covariance based estimation method [31,32] and neural networks [33,34] were recently proposed for despeckling.…”

Section: Speckle Reductionmentioning

confidence: 99%

“…The echo signals generated from these sub-apertures or sub-bands were used to reconstruct images. The frequency bandwidth selection can also be spatially variant according to statistical and physical properties of the signals and noise at different depths [30]. The performance of the speckles reduction depended on the number of the resulting images (N tot ) and the correlation among them.…”

Section: Speckle Reductionmentioning

confidence: 99%

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Decorrelated Compounding in Ultrasound Images

Zhao

2024

Preprint

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<p>This dissertation introduces the decorrelated compounding methods in synthetic transmit aperture (STA) ultrasound imaging and the spatial frequency domain of beamformed ultrasound images. They improve the detectability of low-contrast lesions in terms of lesion signal-to-noise ratio (lSNR), and visual detection. First, a decorrelation procedure was applied to traditional spatial and frequency compounding in STA to improve the lSNR in this dissertation. The decorrelated compounding method shown a better performance of speckle reduction than the conventional incoherent compounding methods at the cost of spatial resolution loss. The overall effect in terms of lSNR, which considered both speckle reduction and spatial resolution loss, indicated that the DC in STA outperformed the Delay-and-Sum (DAS) method. Then, we proposed to apply a two dimensional low-pass filter in the aperture domain to suppress the artifacts caused by the off-axis signals of DC in STA. In clinical applications, strong off-axis signals can be encountered such as irregular borders, calcification or development of vascularity. Both simulation and experiment images demonstrate the effectiveness of the filter. Lastly, the principle of decorrelated compounding was extended beyond STA to the any radiofrequency ultrasound images. The spatial frequency spectrum of beamformed ultrasound images was divided into overlapped sub-domains to generate sub-images for decorrelation and compounding. This method improved lSNR over the DAS method. In addition, the computational complexity was reduced by a factor of 16 compared to DC in STA. This dissertation investigate these decorrelated compounding based methods with the goal of improving the detectability of low-contrast lesions.</p>

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Section: Speckle Reductionmentioning

confidence: 99%

Section: Speckle Reductionmentioning

confidence: 99%

Decorrelated Compounding in Ultrasound Images

Zhao

2024

Preprint

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“…These two envelope signals are added using ; this process is called frequency compounding and is used to mitigate speckle noise [28]. The weighting factors can be determined by analyzing the spectrum of the received echo signal or by calculating the energy loss with a known frequency-dependent attenuation coefficient [29], [30]. After the two envelope signals are summed, log compression is performed to reduce the dynamic range of the US envelope signal.…”

Section: F Back-end Processingmentioning

confidence: 99%

A System-on-Chip Solution for Point-of-Care Ultrasound Imaging Systems: Architecture and ASIC Implementation

Kang

Yoon

Lee

et al. 2016

IEEE Trans. Biomed. Circuits Syst.

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In this paper, we present a novel system-on-chip (SOC) solution for a portable ultrasound imaging system (PUS) for point-of-care applications. The PUS-SOC includes all of the signal processing modules (i.e., the transmit and dynamic receive beamformer modules, mid- and back-end processors, and color Doppler processors) as well as an efficient architecture for hardware-based imaging methods (e.g., dynamic delay calculation, multi-beamforming, and coded excitation and compression). The PUS-SOC was fabricated using a UMC 130-nm NAND process and has 16.8 GFLOPS of computing power with a total equivalent gate count of 12.1 million, which is comparable to a Pentium-4 CPU. The size and power consumption of the PUS-SOC are 27×27 mm(2) and 1.2 W, respectively. Based on the PUS-SOC, a prototype hand-held US imaging system was implemented. Phantom experiments demonstrated that the PUS-SOC can provide appropriate image quality for point-of-care applications with a compact PDA size ( 200×120×45 mm(3)) and 3 hours of battery life.

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“…As introduced in Chapter 4, speckle SNR can be improved by spatial compounding (SC) [14,19,[43][44][45][46][47][48][49][50][51][52][53] and frequency compounding (FC) [16,[61][62][63][64][65][66][67][68][69][70][71]. This chapter will mainly focus on the FC technique.…”

Section: Introductionmentioning

confidence: 99%

“…One challenge which reduces the efficacy of CFC is the frequency dependent attenuation. Some adaptive frequency compounding methods have been proposed such as applying a higher weighting factor to a lower frequency sub-band as the depth increases [66] or using short time Fourier transform (STFT) to analyze the RF spectrum along depth [67]. Frequency equalized compounding (FEC) also estimates the center frequency downshift as the ultrasound pulse travels and the corresponding depth dependent band-pass filters are then designed and implemented [68].…”

Section: Introductionmentioning

confidence: 99%

Novel ultrasound transmission and reconstruction techniques for synthetic transmit aperture imaging

Gong¹

2021

Preprint

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This dissertation describes ultrasound algorithms developed for synthetic transmit aperture (STA) imaging during the transmission and the image reconstruction stages. Images generated using these algorithms demonstrate image quality enhancement both theoretically and experimentally. The advanced algorithms also improve the application of STA imaging. Due to the single element transmission pattern, the low signal-to-noise ratio is a major limitation for STA imaging. A delay-encoded transmission scheme (DE-STA) was designed in this dissertation to encode all the transmissions. The decoded RF signals were equivalent to the standard STA signals, but with a higher SNR. Improved image qualities were observed under DE-STA transmission in terms of lateral resolution (+28%), peak-signal-to-noise ratio (PSNR, +7 dB) and target contrast-to-noise ratio (CNR, +360%) compared to those acquired with the standard STA mode. The stability of DE-STA was analyzed and verified under various noise levels by the special distribution of the singular values of the encoding matrix through singular value decomposition (SVD) (i.e. all the singular values were the same except for the first one and the last one). A more efficient decoding process was also derived based on pseudo-inversion (PI) and the computation complexity was reduced by 2/3. Speckle and undesired sidelobe signals can reduce the lesion CNR and detectability in ultrasound images. Typically, the CNR can be increased by spatial compounding (SC) or frequency compounding (FC) during reconstruction. We proposed methods to implement a 2-dimentional (2-D) aperture domain filter in the SC/FC processes, referred to as filtered spatial compounding (FSC) and filtered frequency compounding (FFC), for synthetic transmit aperture (STA) imaging. Both techniques reduced the sidelobe interference and provided improved lesion CNR. Consequently, the lesion signal-to-noise ratio (lSNR) in FSC and FFC increased (up to +130%), compared to that in the standard delay-and-sum (DAS) method. This dissertation investigates all these proposed advanced ultrasound algorithms, with the end goal of implementing these methods in STA imaging to extend its application in clinic.

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Space Variant Ultrasound Frequency Compounding Based on Noise Characteristics

Cited by 12 publications

References 13 publications

Decorrelated Compounding in Ultrasound Images

Decorrelated Compounding in Ultrasound Images

A System-on-Chip Solution for Point-of-Care Ultrasound Imaging Systems: Architecture and ASIC Implementation

Novel ultrasound transmission and reconstruction techniques for synthetic transmit aperture imaging

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