Smartphone-based portable ultrasound imaging system: A primary result

This paper presents a design solution for a PMUT RX front-end for high performance portable ultrasound medical imaging systems. The PMUT transducer is part of a ID array working in the 1-4 MHz frequency range. Adequate SNR and low power dissipation are ensured in the RX path thanks to a careful design flow focused onto specific imaging requirements, extracted considering the lumped-parameter equivalent circuit model of the transducer. Programmable gain [25dB-35dB] is implemented to comply with a wide range of input acoustic pressure while distortion parameters are designed in order to provide good imaging qualities. Transistor level design and simulations performed in a BCD-SOI 0.16-μm technology are shown as well.

As the lateral resolution and axial imaging depth of a ultrasound image increase, so do the number of transducer elements and the corresponding processing units. Conventional ultrasound systems are often large and expensive due to the intensive requirement of large beamforming arrays. But for applications such as point-of-care diagnostics in rural areas, the movement to a portable and low-power ultrasound imaging system is warranted. To address the low power requirement for portable applications, the proposed beamformer operates in one of three modes, namely quarter, half, and full resolution modes, selectable at runtime. In the first two modes, a subset of elements, with effective pitches of 4x and 2x of the transducer pitch, are processed for low quality images of the full region of interest. These modes provide run-time power reduction, because the Analog Front End (AFE) and Analog-to-Digital Converter (ADC) for the unused channels can be turned off by the feedback control signals from the beamformer. Based on the low quality image, the user can intuitively specify a smaller region where a higher quality image is desired, and the full resolution beamforming mode is used. A system energy model is set up to evaluate the image quality and frame rate performance, while providing realistic power consumption predictions. The model offers fast and accurate behavioral level understanding of the ultrasound system under optimization.

Portable ultrasound systems are useful in point-of-care diagnostic. Improving the image contrast and spatial resolution over a large range of imaging depths while maintaining the minimum area and power are the desiderata in case of ultrasound systems. Adaptive apodization is used for obtaining high contrast and spatial resolution ultrasound images; however, the implementation of adaptive apodization in hardware consumes large area and power. In this paper, an adaptive algorithm is presented for obtaining good image contrast and resolution using low computational complexity. In the proposed apodization algorithm, minimum and maximum variance criteria and normalized cross-correlation are used to enhance the image contrast and spatial resolution over a large range of imaging depths. A resource optimized, IEEE single precision arithmetic-based architecture of the proposed method is also presented in this paper. Field II toolbox and the experimental data taken from the plane-wave imaging challenge in medical ultrasound are used for evaluating the performance of the proposed methods. Simulation and experimental results demonstrate that the proposed method provides better resolution coupled with the improved contrast performance than conventional dual apodization with cross-correlation methods. The architecture of the proposed method consumes 358.66-mW dynamic power and 1122.1 k NAND-2 equivalent gates are found to be in UMC 90-nm CMOS standard cell library. Implementation of the proposed method requires the calculation of inverse square root. A quadratic approximation-based inverse square root calculation method and its datapath to support IEEE single precision arithmetic are also presented. The datapath of the inverse square root calculator reduces the memory requirement up to 70% which need to be adopted in pursuit of higher performances.

High performance portable ultrasound imaging system is demanded by a wide variety of point of care applications. Ultrasound system minimization and improvement have been proven in the past several years. One of the main driving forces for portable ultrasound system minimization and improvement is the advanced semiconductor technology. Besides, transducer technology is further enhancing system sensitivity and reducing system cost. Corresponding silicon processes were selected for achieving low power, low noise and compact size in ultrasound analog front-end (AFE) design. The combination of bipolar and CMOS processes achieves significant power, noise and size reduction, as well as superior CW performance. Key considerations of ultrasound analog front-end were discussed and analyzed. Standard test procedures were developed to assist the design.

Portable laser diode-based multispectral photoacoustic and ultrasound imaging system for point-of-care screening applications

Portable High-Frequency Ultrasound Imaging System Design and Hardware Considerations

Whole Breast Lesion Detection Using Naive Bayes Classifier for Portable Ultrasound

3D position of radiation sources using an automated gamma camera and ML algorithm with energy-dependent response functions

Pocket mobile smartphone system for the point-of-care submandibular ultrasonography

A requirement to reconstruct photoacoustic (PA) image is to have a synchronized channel data acquisition with laser firing. Unfortunately, most clinical ultrasound (US) systems don’t offer an interface to obtain synchronized channel data. To broaden the impact of clinical PA imaging, we propose a PA image reconstruction algorithm utilizing US B-mode image, which is readily available from clinical scanners. US B-mode image involves a series of signal processing including beamforming, followed by envelope detection, and end with log compression. Yet, it will be defocused when PA signals are input due to incorrect delay function. Our approach is to reverse the order of image processing steps and recover the original US post-beamformed radio-frequency (RF) data, in which a synthetic aperture based PA rebeamforming algorithm can be further applied. Taking B-mode image as the input, we firstly recovered US postbeamformed RF data by applying log decompression and convoluting an acoustic impulse response to combine carrier frequency information. Then, the US post-beamformed RF data is utilized as pre-beamformed RF data for the adaptive PA beamforming algorithm, and the new delay function is applied by taking into account that the focus depth in US beamforming is at the half depth of the PA case. The feasibility of the proposed method was validated through simulation, and was experimentally demonstrated using an acoustic point source. The point source was successfully beamformed from a US B-mode image, and the full with at the half maximum of the point improved 3.97 times. Comparing this result to the ground-truth reconstruction using channel data, the FWHM was slightly degraded with 1.28 times caused by information loss during envelope detection and convolution of the RF information.

The registration of a three-dimensional (3D) ultrasound (US) image with a computed tomography (CT) or magnetic resonance image is beneficial in various clinical applications such as diagnosis and image-guided intervention of the liver. However, conventional methods usually require a time-consuming and inconvenient manual process for pre-alignment, and the success of this process strongly depends on the proper selection of initial transformation parameters. In this paper, we present an automatic feature-based affine registration procedure of 3D intra-operative US and pre-operative CT images of the liver. In the registration procedure, we first segment vessel lumens and the liver surface from a 3D B-mode US image. We then automatically estimate an initial registration transformation by using the proposed edge matching algorithm. The algorithm finds the most likely correspondences between the vessel centerlines of both images in a non-iterative manner based on a modified Viterbi algorithm. Finally, the registration is iteratively refined on the basis of the global affine transformation by jointly using the vessel and liver surface information. The proposed registration algorithm is validated on synthesized datasets and 20 clinical datasets, through both qualitative and quantitative evaluations. Experimental results show that automatic registration can be successfully achieved between 3D B-mode US and CT images even with a large initial misalignment.

Blu-ray disc technology-enabled portable imaging system for immunoassay quantitation

Study of the evolution in space and time of water diffusion in a leaf through a sub-terahertz portable imaging system

The ability to perform coronary angiography rapidly at the bedside has multiple potential applications. This study was designed to determine whether a novel portable angiographic system (OEC Medical Systems, series 9600, Salt Lake City, Utah) is capable of producing high-quality angiograms. In 29 patients (70 vessels) undergoing elective catheterization in a conventional fixed laboratory (Siemens HICOR, Erlangen, Germany), we compared images obtained with the portable system to those from conventional fixed system. The portable system was 100% accurate in detecting both insignificant narrowing as well as significant stenoses (|l750% narrowing). There was complete concordance between systems for lesion location, TIMI flow, and collaterals. Thirty-two stenoses were analyzed in detail. Both quantitative and qualitative percent stenosis demonstrated similar value for lesion severity with both systems (R = 0.95, Kappa = 0.77, P l8 0.001, respectively). Accuracy of lesion morphology by the portable system was similar to the fixed system (calcification 80%, eccentricity 92%). These findings demonstrate that a portable imaging system can produce high-quality coronary angiograms. Cathet. Cardiovasc. Diagn. 41:449–455, 1997. © 1997 Wiley-Liss, Inc.

From the tables chronicling ultrasound imaging developments and enabling technologies, it is evident that there is often a time lag between the appearance of a technology and its effect. The most dramatic changes have been through the continual miniaturization of electronics in accordance with Moore’s law. Smaller size components led to the first commercially available phased array imaging systems as well as new portable imaging systems which weigh only a few pounds. Moore’s law is apparently approaching physical limits, and a second Moore’s law predicts rapidly increasing production costs with reduced chip size. Because of the time lag of technology implementation, the full effect of the latest devel opments have not had their full effect on ultrasound imaging.