Ultrasound Systems for Biometric Recognition

Novel Applications of Ultrasound Technology to Visualize and Characterize Myofascial Trigger Points and Surrounding Soft Tissue

Diaphragm muscle dysfunction is increasingly recognized as an important element of several diseases including neuromuscular disease, chronic obstructive pulmonary disease and diaphragm dysfunction in critically ill patients. Functional evaluation of the diaphragm is challenging. Use of volitional maneuvers to test the diaphragm can be limited by patient effort. Non-volitional tests such as those using neuromuscular stimulation are technically complex, since the muscle itself is relatively inaccessible. As such, there is a growing interest in using imaging techniques to characterize diaphragm muscle dysfunction. Selecting the appropriate imaging technique for a given clinical scenario is a critical step in the evaluation of patients suspected of having diaphragm dysfunction. In this review, we aim to present a detailed analysis of evidence for the use of ultrasound and non-ultrasound imaging techniques in the assessment of diaphragm dysfunction. We highlight the utility of the qualitative information gathered by ultrasound imaging as a means to assess integrity, excursion, thickness, and thickening of the diaphragm. In contrast, quantitative ultrasound analysis of the diaphragm is marred by inherent limitations of this technique, and we provide a detailed examination of these limitations. We evaluate non-ultrasound imaging modalities that apply static techniques (chest radiograph, computerized tomography and magnetic resonance imaging), used to assess muscle position, shape and dimension. We also evaluate non-ultrasound imaging modalities that apply dynamic imaging (fluoroscopy and dynamic magnetic resonance imaging) to assess diaphragm motion. Finally, we critically review the application of each of these techniques in the clinical setting when diaphragm dysfunction is suspected.

in vivo and ex vivo prostate cancer imaging using an ultrasonic tissue-typing technique for imaging-guided dose escalation of prostate cancer radiotherapy

In this work, the design and development of a 128-channel transceiver hardware for medical ultrasound imaging systems and research is presented. The proposed hardware solution integrates the analog front-end (AFE) sections, high voltage transmit pulser sections, field programmable gate array (FPGA)-based transmit beamforming and control logic, time gain compensation (TGC) and continuous (CW) Doppler functional circuits, and the necessary power supplies (high voltage (HV) and low voltage (LV)) into a single board. In addition, it integrates pervasive segments like power, clock tree sections, and power management and debugger logic. The developed transceiver solution helps to advance the research in medical ultrasound imaging techniques and technologies. To prototype an ultrasound imaging system, the developed hardware can be interfaced with a 128-channel ultrasound transducer array and an FPGA-based signal processing module. As the transceiver hardware is designed with commercially available chipsets, it provides the flexibility to programme the ultrasound AFE signal chain, transmit beamforming and the arbitrary transmit wave pattern. Besides, compared to the commercial open ultrasound research scanners, the flexibility to interface FPGA-based signal processing module helps to investigate the performance of hardware realisation of various ultrasound signal processing algorithms. Moreover, the work realises a single-board transceiver solution for multichannel ultrasound system fulfilment.

Hydrops Fetalis is an abnormal condition in the fetus by an accretion of unusual fluid or edema in two or more fetal cavities for instance ascites, pericardial and pleural effusion. Accumulation of atypical fluid above 2 mm needs extra attention of radiologists. Ultrasound imaging technique helps to diagnose the fluid accumulation within the pericardial tissues. The trained medicinal practitioners also find difficult to analyse the hydrops due to the low assessment gray scale ultrasound images. The segmentation of hydrops fetalis from the fetal heart ultrasound image helps the sonographists and pediatrists to diagnose easily and effectively at the early stage itself. The low quality and poor resolution ultrasound image, make the segmentation process difficult. We use the spatially constrained-distance regularized level set evolution algorithm for segmenting the hydrops region.

The updated roles of new ultrasound imaging techniques in assessing carotid vulnerable plaques

Piezoelectric micromachined ultrasound transducer (pMUT) technology shows promise for wearable ultrasound applications, although with limitations in acquisition performance compared to standard transducers. To translate Pulse Wave Imaging (PWI)-an ultrasound imaging technique that evaluates local arterial mechanics-into wearable applications, this study investigated the performance of integrating a miniaturized pMUT array into the PWI pipeline. Nine (n = 9) carotid arteries were scanned with a miniaturized pMUT array and an L7-4 linear transducer. Metrics like pulse wave velocity at end-diastole (PWVED) and end-systole (PWVES), compliance (CED, CES), and carotid pulse pressure (PPC) were compared between imaging arrays. Lower SNR of axial wall velocities (SNRvPWI) at end-diastole (L7-4: 47.9 ± 6.8 dB, pMUT: 43.3 ± 7.4 dB) and end-systole (L7-4: 45.4 ± 6.4 dB, pMUT: 38.1 ± 6.5 dB), and trends of higher coefficient of variation (CV) were found for PWI performed with the pMUT array compared to the L7-4. Bland-Altman analysis identified good agreement between the L7-4 and pMUT array for average PWVED (bias = -0.02 ± 0.42 m/s), PWVES (bias = -0.38 ± 1.3 m/s), CED (bias = 0.04 × 10-9 ± 0.24 × 10-9 m2/Pa), CES (bias = 0.11 × 10-9 ± 0.38 × 10-9 m2/Pa) and PPC (bias = 1.06 ± 5.08 mmHg). The findings revealed comparable performance between the miniaturized pMUT array and L7-4 for PWI, highlighting the versatility of the PWI technique. This feasibility study illustrates the potential for translating PWI into wearable configurations, opening new avenues for cardiovascular health monitoring.

Carpal tunnel syndrome (CTS) is the common entrapment neuropathy that occurs due to compression of the median nerve at the wrist. Ultrasound images have been used to highlight anatomical variants of the median nerve, and CTS is thought to be associated to enlargement of the cross-sectional area (CSA) of the median nerve. However, there remains controversy regarding the most appropriate cutoff values of the computer measurements including the CSA, flattening ratio, and palmar bowing of median nerve, especially given that they can be influenced by image artifacts and factors that differ between individual patients. This study proposed a modified ultrasound compound imaging technique by moving fingers to reduce image artifacts, and the estimates of the normalized CSA [i.e., CSA at the wrist (CSAw) to CSA at the midforearm] with the aim of reducing discrepancies in CSA estimates and improving the ability of CTS discrimination. The subjects were examined with their arms supine and while they were making repetitive movements of their fingers (from an open palm into a clenched fist) within 3 s. By a commercial ultrasound scanner with a 10-MHz linear array transducer, a total of 70 images were acquired in each subject. The frame rate of ultrasound system was 25 fps. Nine frames in the acquisition sequence that had produced partial speckle decorrelation were incoherently added to form a compound image, and the inplane motion of them was corrected using the multilevel block-sum pyramid algorithm. The manual contours outlined by ten experimenters and three physicians were used to test the performance in determining the boundary of the median nerve. The receiver operating characteristic (ROC) curve was used to evaluate the usefulness of the estimates in distinguishing healthy volunteers from CTS patients. The manual contours of the median nerve in the compound images had an average area overlap exceeding 90% and relatively small area errors. The areas under the ROC curve obtained using the CSAw estimates for the original and compound images were 0.60 ± 0.09 (mean ± standard error) and 0.80 ± 0.05, respectively; that using normalized CSA estimates for the original and compound images were 0.76 ± 0.04 and 0.89 ± 0.04, respectively. The results show that variations in the CSAw values of compound images for healthy overweight and obese subjects can adversely influence CTS diagnosis, but that this can be overcome using the normalized CSA estimate of compound images. Compound imaging provides images of superior quality for determining the location of the median nerve boundary. Using the normalized CSA estimate would assist in eliminating problems associated with variability between populations, since the subject becomes his or her own internal control, thereby improving the ultrasound-based diagnosis of CTS.

Traditional identity verification of students based on the human proctoring approach can cause a scam identity verification and ineffective processing time, particularly among vast groups of students. Most student identification cards outdated personal information. Several biometric recognition approaches have been proposed to strengthen students’ identity verification. Most educational adoption technologies struggle with evaluation and validation techniques to ensure that biometric recognition systems are unsuitable for utilization and implementation for student identity verification. This study presents the internet of things to develop flexible biometric recognition systems and an approach to assess the quality of biometric systems for educational use by investigating the effectiveness of identity verification of various biometric recognition technologies compared to the traditional verification method. The unimodal, multimodal, and semi-multimodal biometric technologies were tested using the developed internet of things-base biometric recognition systems examined by applying the proposed quality metrics of scoring factors based on accuracy, error rate, processing time, and cost. Hundreds of undergraduate exam takers were a sample group. Key findings indicate that the designed and presented systems suitably attain identity verification of exam students using a unimodal biometric. The unimodal facial biometric system promises excellent support. A unimodal fingerprint biometric system ensures second excellent aid for student identity verification. However, multimodal and semi-multimodal biometric systems provide better accuracy with fewer handling times and higher costs. This study contributes significantly to the knowledge of utilizing biometric recognition for identity verification in smart educational applications.

At present, early detection of the potential risk of atherosclerosis and prevention is of great significance to reduce the occurrence of stroke. This study aims to explore the value of combining the wall shear stress measured by ultrasound vector flow imaging technique and sound touch elastography of common carotid artery in normal adults using the Mindray Resona 7 ultrasound system. Forty volunteers (mean age 39.5 y, 23 females, 17 males) were divided into four groups according to their age. All volunteers underwent ultrasound carotid artery examination, and the values of wall shear stress and elasticity on the posterior wall of the common carotid artery were measured using advanced imaging functions, vector flow imaging technique, and sound touch elastography. Different cut-off values of wall shear stress were used to investigate the significance between two groups with corresponding sound touch elastography values. It can be seen that the statistical difference could be found when the mean wall shear stress was larger than 1.5 Pa approximately (statistical significance was defined when P < 0.05), and the sound touch elastography value was positively correlated with the wall shear stress value. This study reveals that the combination of wall shear stress and sound touch elastography is an effective and feasible method for assessing carotid artery health. When the mean wall shear stress value is over 1.5 Pa, the corresponding sound touch elastography value increases significantly. The risk of atherosclerosis increases with the stiffness of blood vessel walls.

Ultrasound envelope statistics imaging, including ultrasound Nakagami imaging, homodyned-K imaging, and information entropy imaging, is an important group of quantitative ultrasound techniques for characterizing tissue scatterer distribution patterns, such as scatterer concentrations and arrangements. In this study, we proposed a machine learning approach to integrate the strength of multimodality quantitative ultrasound envelope statistics imaging techniques and applied it to detecting microwave ablation induced thermal lesions in porcine liver ex vivo. The quantitative ultrasound parameters included were homodyned-K α which is a scatterer clustering parameter related to the effective scatterer number per resolution cell, Nakagami m which is a shape parameter of the envelope probability density function, and Shannon entropy which is a measure of signal uncertainty or complexity. Specifically, the homodyned-K log10(α), Nakagami-m, and horizontally normalized Shannon entropy parameters were combined as input features to train a support vector machine (SVM) model to classify thermal lesions with higher scatterer concentrations from normal tissues with lower scatterer concentrations. Through heterogeneous phantom simulations based on Field II, the proposed SVM model showed a classification accuracy above 0.90; the area accuracy and Dice score of higher-scatterer-concentration zone identification exceeded 83% and 0.86, respectively, with the Hausdorff distance <26. Microwave ablation experiments of porcine liver ex vivo at 60–80 W, 1–3 min showed that the SVM model achieved a classification accuracy of 0.85; compared with single log10(α),m, or hNSE parametric imaging, the SVM model achieved the highest area accuracy (89.1%) and Dice score (0.77) as well as the smallest Hausdorff distance (46.38) of coagulation zone identification. We concluded that the proposed multimodality quantitative ultrasound envelope statistics imaging based SVM approach can enhance the capability to characterize tissue scatterer distribution patterns and has the potential to detect the thermal lesions induced by microwave ablation.

The conical scanner: a two transducer ultrasound scatter imaging technique.

Crystallisation is a crucial step in many industrial processes. Many sensors are being investigated for monitoring such processes to enhance the efficiency of them. Ultrasound techniques have been used for particle sizing characterization of liquid suspensions, in crystallisation process. An ultrasound tomography system with an array of ultrasound sensors can provide spatial information inside the process when compared to single-measurement systems. In this study, the batch crystallisation experiments have been conducted in a lab-scale reactor in calcium carbonate crystallisation. Real-time ultrasound tomographic imaging is done via a contactless ultrasound tomography sensor array. The effect of the injection rate and the stirring speed was considered as two control parameters in these crystallisation functions. Transmission mode ultrasound tomography comprises 32 piezoelectric transducers with central frequency of 40 kHz has been used. The process-based experimental investigation shows the capability of the proposed ultrasound tomography system for crystallisation process monitoring. Information on process dynamics, as well as process malfunction, can be obtained via the ultrasound tomography system.

Uterine positional changes can reduce the accuracy of radiotherapy for cervical cancer patients. The purpose of this study was to; 1) Quantify the inter-fractional uterine displacement using a novel 3D ultrasound (US) imaging system, and 2) Compare the result with the bone match shift determined by Cone- Beam CT (CBCT) imaging.Five cervical cancer patients were enrolled in the study. Three of them underwent weekly CBCT imaging prior to treatment and bone match shift was applied. After treatment delivery they underwent a weekly US scan. The transabdominal scans were conducted using a Clarity US system (Clarity® Model 310C00). Uterine positional shifts based on soft-tissue match using US was performed and compared to bone match shifts for the three directions. Mean value (&plusmn;1 SD) of the US shifts were (mm); anterior-posterior (A/P): (3.8&plusmn;5.5), superior-inferior (S/I) (-3.5&plusmn;5.2), and left-right (L/R): (0.4&plusmn;4.9). The variations were larger than the CBCT shifts. The largest inter-fractional displacement was from -2 mm to +14 mm in the AP-direction for patient 3. Thus, CBCT bone matching underestimates the uterine positional displacement due to neglecting internal uterine positional change to the bone structures. Since the US images were significantly better than the CBCT images in terms of soft-tissue visualization, the US system can provide an optional image-guided radiation therapy (IGRT) system. US imaging might be a better IGRT system than CBCT, despite difficulty in capturing the entire uterus. Uterine shifts based on US imaging contains relative uterus-bone displacement, which is not taken into consideration using CBCT bone match.

Biometric recognition through 3D ultrasound hand geometry