Conventional Ultrasound Scanner Research Articles

MP30-12 VALIDATION OF MOBILE APPLICATION MEASURING VOIDED VOLUME: A PILOT PROSPECTIVE STUDY

You have accessJournal of UrologyCME1 May 2022MP30-12 VALIDATION OF MOBILE APPLICATION MEASURING VOIDED VOLUME: A PILOT PROSPECTIVE STUDY Hwanik Kim, Jin Hyuck Kim, Changhee Ye, Gyoohwan Jung, Jung Kwon Kim, Hakmin Lee, Seong Jin Jeong, and Sangchul Lee Hwanik KimHwanik Kim More articles by this author , Jin Hyuck KimJin Hyuck Kim More articles by this author , Changhee YeChanghee Ye More articles by this author , Gyoohwan JungGyoohwan Jung More articles by this author , Jung Kwon KimJung Kwon Kim More articles by this author , Hakmin LeeHakmin Lee More articles by this author , Seong Jin JeongSeong Jin Jeong More articles by this author , and Sangchul LeeSangchul Lee More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002573.12AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Comparing urine flow tests performed at the clinic with the actual urination at home, there can be a mental burden and straining of urine that can affect the test results. The need for a comfortable, convenient, and even portable, home-based device has led to the development of novel uroflowmetry technology. This study aimed to evaluate the accuracy and reliability of a new smartphone-based acoustic voiding volume measurement application compared to conventional ultrasound bladder volume scanner. METHODS: A total of 12 subjects from September 2020 to March 2021 were prospectively enrolled with informed consent to compare novel acoustic voiding volume measurement to conventional ultrasound bladder volume scanner. 2 subjects were excluded their measurement do not meet our standard of sound quality (i.e. voiding in environment with very loud fan noise, voiding to the wall, door slams). Finally, 10 patients with 50 voiding measurements were included for analysis. The value measured before urination by bladder scanner (A), the value measured after urination by bladder scanner (B), and the value of voided volume measured by smartphone-based acoustic voiding volume measurement mobile application (C) were compared between the 2 techniques. Reliability and accuracy of the voided volume results were compared using Pearson correlation coefficient, and student t-test, respectively. RESULTS: 10 healthy volunteers were included in the study. Median age was 53.5. Median values of uroflowmetry proflile are as follows: Qmax: 16.3mL/s, Voided volume: 256.8mL, and postvoid residual urine: 7.5mL. Voided volume between the 2 techniques revealed strong visual correlation (r=0.71, p=0.02). When compared to conventional uroflowmetry. When analyzed separately for each individual, each participant showed stronger correlation (range: 0 59-1.00). CONCLUSIONS: The acoustic voiding volume measurement application can take over the role of traditional bladder scan resulted from our validation. Through comparison of bladder scan measurements before and after urination, it was confirmed that the urine volume measurement using the smartphone PRIVY application was accurate. PRIVY application can be a breakthrough that can lower the barriers to entry to health management of patients' urination. Further large-scale studies will further increase the credibility of our results. Source of Funding: N/A © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e482 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hwanik Kim More articles by this author Jin Hyuck Kim More articles by this author Changhee Ye More articles by this author Gyoohwan Jung More articles by this author Jung Kwon Kim More articles by this author Hakmin Lee More articles by this author Seong Jin Jeong More articles by this author Sangchul Lee More articles by this author Expand All Advertisement PDF DownloadLoading ...

A Robust and Fast Method for 2-D Shear Wave Speed Calculation.

We developed a new method, called the tangent plane method (TPM), for more efficiently and accurately estimating 2-D shear wave speed (SWS) from any direction of wave propagation. In this technique, we estimate SWS by solving the Eikonal equation because this approach is more robust to noise. To further enhance the performance, we computed the tangent plane of the arrival time surface. To evaluate the approach, we performed simulations and also conducted phantom studies. Simulation studies showed that TPM was more robust to noise than the conventional methods such as 2-D cross correlation (CC) and the distance method. The contrast/CNR for an inclusion (69 kPa; manufacturer provided stiffness) of a phantom is 0.54/4.17, 0.54/1.82, and 0.46/1.22. SWS results [mean and standard deviation (SD)] were 4.41 ± 0.49, 4.62 ± 0.85, and 3.66 ± 0.99 m/s, respectively, while the manufacturer's reported value (mean and range) is 4.81 ± 0.49 m/s. This shows that TPM has the higher CNR and lower SD than other methods. To increase the computation speed, an iterative version of TPM (ITPM) was also developed, which calculated the time-of-flight iteratively. ITPM reduced the computation time to 3.6%, i.e., from 748 to 27 s. In vivo case analysis demonstrated the feasibility of using the conventional ultrasound scanner for the proposed 2-D SWS algorithms.

Sono-angiography for dialysis vascular access based on the freehand 2D ultrasound scanning.

Dialysis vascular access, preferably an autogenous arteriovenous fistula, remains an end stage renal disease (ESRD) patient's lifeline providing a means of connecting the patient to the dialysis machine. Once an access is created, the current gold standard of care for maintenance of vascular access is angiography and angioplasty to treat stenosis. While point of care 2D ultrasound has been used to detect access problems, we sought to reproduce angiographic results comparable to the gold standard angiogram (fistulogram) using ultrasound data acquired from a conventional 2D ultrasound scanner. A 2D ultrasound probe was used to acquire a series of cross sectional images of the vascular access including arteriovenous anastomosis of a subject with a radio-cephalic fistula. These 2D B-mode images were used for 3D vessel reconstruction by binary thresholding to categorize vascular versus non-vascular structures followed by standard image segmentation to select the structure representative of dialysis vascular access and morphologic filtering. Image processing was done using open source Python Software. The open source software was able to: (1) view the gold standard fistulogram images, (2) reconstruct 2D planar images of the fistula from ultrasound data as viewed from the top, analogous to computerized tomography images, and (3) construct a 2D representation of vascular access similar to the angiogram. We present a simple approach to obtain an angiogram-like representation of the vascular access from readily available, non-proprietary 2D ultrasound data in the point of care setting. While the sono-angiogram is not intended to replace angiography, it may be useful in providing 3D imaging at the point of care in the dialysis unit, outpatient clinic, or for pre-operative planning for interventional procedures. Future work will focus on improving the robustness and quality of the imaging data while preserving the straightforward freehand approach used for ultrasound data acquisition.

Time-Aligned Plane Wave Compounding Methods for High-Frame-Rate Shear Wave Elastography: Experimental Validation and Performance Assessment on Tissue Phantoms

Shear wave elastography (SWE) is an ultrasonic technique able to quantitatively assess the mechanical properties of tissues by combining acoustic radiation force and ultrafast imaging. While utilizing coherent plane wave compounding enhances echo and shear wave motion signal-to-noise ratio (SNR), it also reduces the effective pulse repetition frequency (PRFe), affecting the accuracy of the measurements of motion and, consequently, of material properties. It is important to maintain both high-motion SNR and PRFe, particularly for the characterization of (material and/or geometrical) dispersive tissues such as arteries. This work proposes a method for SWE measurements with high SNR, while maintaining a high PRFe, using conventional clinical ultrasound scanners. A time alignment process is applied after acquiring data from plane wave transmissions at different angles. The time alignment uses interpolation to obtain data points at higher frame rates, and the time-aligned data are compounded to increase the SNR. The method is used for SWE in tissue-mimicking phantoms of different stiffness and is compared with traditional plane wave compounding. Increases of 58% and 36% in spatial and temporal bandwidth compared with conventional plane wave compounding, respectively, can be achieved for SWE measurements of representative arterial stiffness values. Improvements in phase velocity accuracy and bandwidth in an arterial phantom are also described, to emphasize the beneficial advantage in dispersive cases.

Broadband All-Optical Plane-Wave Ultrasound Imaging System Based on a Fabry-Perot Scanner.

A broadband all-optical plane-wave ultrasound imaging system for high-resolution 3-D imaging of biological tissues is presented. The system is based on a planar Fabry-Perot (FP) scanner for ultrasound detection and the photoacoustic generation of ultrasound in a carbon-nanotube-polydimethylsiloxane (CNT-PDMS) composite film. The FP sensor head was coated with the CNT-PDMS film which acts as an ultrasound transmitting layer for pulse-echo imaging. Exciting the CNT-PDMS coating with nanosecond laser pulses generated monopolar plane-wave ultrasound pulses with MPa-range peak pressures and a -6-dB bandwidth of 22 MHz, which were transmitted into the target. The resulting scattered acoustic field was detected across a 15 mm ×15 mm scan area with a step size of 100 [Formula: see text] and an optically defined element size of [Formula: see text]. The -3-dB bandwidth of the sensor was 30 MHz. A 3-D image of the scatterer distribution was then recovered using a k -space reconstruction algorithm. To obtain a measure of spatial resolution, the instrument line-spread function (LSF) was measured as a function of position. At the center of the scan area, the depth-dependent lateral LSF ranged from 46 to 65 [Formula: see text] for depths between 1 and 12 mm. The vertical LSF was independent of position and measured to be [Formula: see text] over the entire field of view. To demonstrate the ability of the system to provide high-resolution 3-D images, phantoms with well-defined scattering structures of arbitrary geometry were imaged. To demonstrate its suitability for imaging biological tissues, phantoms with similar impedance mismatches, sound speed and scattering properties to those present in the tissue, and ex vivo tissue samples were imaged. Compared with conventional piezoelectric-based ultrasound scanners, this approach offers the potential for improved image quality and higher resolution for superficial tissue imaging. Since the FP scanner is capable of high-resolution 3-D photoacoustic imaging of in vivo biological tissues, the system could ultimately be developed into an instrument for dual-mode all-optical ultrasound and photoacoustic imaging.

Three-dimensional shear wave elastography on conventional ultrasound scanners with external vibration

Two-dimensional (2D) ultrasound shear wave elastography (SWE) has been widely used for soft tissue properties assessment. Given that shear waves propagate in three dimensions (3D), extending SWE from 2D to 3D is important for comprehensive and accurate stiffness measurement. However, implementation of 3D SWE on a conventional ultrasound scanner is challenging due to the low volume rate (tens of Hertz) associated with limited parallel receive capability of the scanner’s hardware beamformer. Therefore, we developed an external mechanical vibration-based 3D SWE technique allowing robust 3D shear wave tracking and speed reconstruction for conventional scanners. The aliased shear wave signal detected with a sub-Nyquist sampling frequency was corrected by leveraging the cyclic nature of the sinusoidal shear wave generated by the external vibrator. Shear wave signals from different sub-volumes were aligned in temporal direction to correct time delays from sequential pulse-echo events, followed by 3D speed reconstruction using a 3D local frequency estimation algorithm. The technique was validated on liver fibrosis phantoms with different stiffness, showing good correlation (r = 0.99, p < 0.001) with values measured from a state-of-the-art SWE system (GE LOGIQ E9). The phantoms with different stiffnesses can be well-differentiated regardless of the external vibrator position, indicating the feasibility of the 3D SWE with regard to different shear wave propagation scenarios. Finally, shear wave speed calculated by the 3D method correlated well with magnetic resonance elastography performed on human liver (r = 0.93, p = 0.02), demonstrating the in vivo feasibility. The proposed technique relies on low volume rate imaging and can be implemented on the widely available clinical ultrasound scanners, facilitating its clinical translation to improve liver fibrosis evaluation.

A time-aligned plane wave compounding method for high frame rate shear wave elastography

Shear wave elastography (SWE) is an established ultrasonic imaging technique, that provides quantitative measurements of tissue mechanical properties. This technique relies on the combination of acoustic radiation force push beams to generate propagating shear waves and ultrafast imaging, which allows high two-dimensional imaging frame rates to capture the induced motion. Utilizing coherent plane wave compounding (PWC) can improve signal-to-noise ratio (SNR) of acquired data. While the image quality improves, the pulse repetition frequency (PRF) is reduced, reaching limiting bandwidths to perform SWE. To address these challenges, a method for making SWE measurements with high PRF and SNR is presented. The idea follows the Time Aligned Sequential Tracking method, proposed to allow SWE with enhanced SNR in conventional clinical ultrasound scanners. The time alignment process is applied here to the full field-of-view, acquired by using plane waves transmitted at different angles. In this way, the full PRF and SNR gains are obtained. Results are shown from experiments in tissue-mimicking phantoms, where motion and extracted shear wave velocity are compared for the traditional and proposed data processing schemes. Preliminary results on arterial phantoms are also discussed, to emphasize the beneficial effects of the method in dispersive geometries.

Use of pocket-sized ultrasound device in vascular surgery.

Ultrasound is widely used in vascular surgery. Pocket-sized ultrasound devices have limited functionality compared to conventional ultrasound scanners, but are cheaper and highly portable. The aim of this study was to investigate whether vascular surgeons could benefit from using a pocket ultrasound device in everyday clinical practice. Pocket-sized ultrasound devices were made available in the Department of Vascular Surgery at St. Olavs Hospital, Trondheim University Hospital, for a 10-month period. Eleven doctors participated and were free to choose between a conventional ultrasound scanner and a pocket ultrasound device. After each use of a pocket ultrasound device, participants completed a form describing the indication for use, whether the clinical question was answered, the image quality experienced and the need for supplementary diagnostic imaging. At the end of the study period, each user completed a questionnaire. Pocket ultrasound devices were mainly used preoperatively. The clinical question was answered in 51 (85%) of 60 registered examinations with a pocket ultrasound device. Image quality was subjectively rated as good in 32 (53%) examinations, moderate in 21 (35%) and poor in 7 (12%), with the clinical question answered in 94%, 90% and 29% of cases, respectively. Doctors with less than five years of experience with ultrasound chose pocket ultrasound more frequently than more experienced users. For the examinations selected, the images supplied by the pocket ultrasound device were generally of sufficient quality and often answered the clinical question. Pocket ultrasound devices can be a useful supplementary tool in vascular surgery, especially for venous examinations.

Quantitative breast elastography from B-mode images.

Elastography images provide information about the mechanical properties of soft tissue in a noninvasive way and can be useful to identify abnormalities and ascertain differential diagnoses of suspicious prior findings obtained through mammography ultrasound. In this work we investigate, from a physics point of view, the feasibility of quantifying the Young's modulus of breast tissue from the autocorrelation of a diffuse acoustic field computed from a sequence of B-mode images acquired through conventional ultrasound scanners. Inspired in the seismological approach of retrieving the Green's function by cross-correlation of diffuse fields, we obtained a quantitative expression that relates the local shear modulus of soft tissue to the autocorrelation of the displacement field generated by the presence of an acoustic diffuse field in the medium. In addition, we designed a mechanical prototype device adaptable to the breast anatomy, in order to create the necessary conditions in terms of diffuse field generation. The device is easy to handle, and its positioning does not interfere with the ultrasonic probe, being friendly to use within the clinical environment. The displacement field was measured from a sequence of B-mode images acquired at standard frame rates (30-50Hz) with conventional ultrasound equipment. This method was tested in a breast tissue mimicking phantom using two standard ultrasound scanners (Toshiba Nemio NX and SIUI (Shantou Institute of Ultrasonic Instruments) Apogee 3800) and an open source research device (Verasonics V3.07 US). We also performed an invivo measurement as a preliminary validation. In the reconstructed Young's modulus maps the inclusions were identified and the obtained quantitative results for an inclusion and the background of the phantom were 60.0±4.0 and 20.4±0.5KPa for the Toshiba equipment, 65.5±6.9 and 22.6±2.7KPa for the SIUI equipment and 67.2±7.3KPa and 22.6±2.8KPa for the Verasonic scanner. These results are in good agreement with the values reported by the phantom's manufacturer of 60 and 20KPa for the inclusion and the background, respectively. In the case of the invivo measurement, the obtained images are in accordance with the patient known pathology (BI-RADS 5, Infiltrating Ductal Carcinoma, Score 6). The pathological breast showed a heterogeneous elasticity map with a mean Young's modulus of 98.1±12.9KPa, while the normal breast displayed a homogeneous map with a mean Young's modulus of 24.7±8.1KPa. We successfully reconstructed the Young's modulus map of the breast tissue mimicking phantom and of a real breast tumor using B-mode images acquired with conventional ultrasound scanners. The results obtained in this work support that our technique can be developed as a medical tool to obtain quantitative breast tissue elasticity maps.

1P5-10 Development of Backscatter Coefficient Evaluation Method on Conventional Ultrasound Scanner – Comparison with Single-Element Transducer

1P5-10 Development of Backscatter Coefficient Evaluation Method on Conventional Ultrasound Scanner – Comparison with Single-Element Transducer

Pediatric Transthoracic Cardiac Vector Flow Imaging - A Preliminary Pictorial Study.

Purpose Conventional pediatric echocardiography is crucial for diagnosing congenital heart disease (CHD), but the technique is impaired by angle dependency. Vector flow imaging (VFI) is an angle-independent noninvasive ultrasound alternative for blood flow assessment and can assess complex flow patterns not visible on conventional Doppler ultrasound. Materials and Methods 12 healthy newborns and 3 infants with CHD were examined with transthoracic cardiac VFI using a conventional ultrasound scanner and a linear array. Results VFI examinations revealed common cardiac flow patterns among the healthy newborns, and flow changes among the infants with CHD not previously reported with conventional echocardiography. Conclusion For assessment of cardiac flow in the normal and diseased pediatric heart, VFI may provide additional information compared to conventional echocardiography and become a useful diagnostic tool.

Coupling Myocardium and Vortex Dynamics in Diverging-Wave Echocardiography.

Echocardiography is widely used to provide critical left ventricular indices describing myocardial motion and blood inflow velocity. Tissue motion and blood flow are strongly connected and interdependent in the ventricle. During cardiac relaxation, rapid filling leads to the formation of a vortical blood flow pattern. In this paper, we introduce a high-frame-rate method to track vortex dynamics alongside myocardium motion, in a single heartbeat. Cardiac triplex imaging (B-mode + tissue Doppler + color Doppler) was obtained by insonating the left ventricle with diverging waves. We used coherent compounding with integrated motion compensation to obtain high-quality B-mode images. Tissue Doppler was retrieved and the septal and lateral velocities of the mitral annulus were deduced. A rate of ~80 triplex images/s was obtained. Vortex dynamics was analyzed by Doppler vortography. Blood vortex signature maps were used to track the vortex and compute core vorticities. The sequence was implemented in a Verasonics scanner with a 2.5-MHz phased array and tested in vivo in 12 healthy volunteers. Two main peaks appeared on the vorticity curves. These peaks were synchronized with the mitral inflow velocities with a small delay. We observed a relationship between the tissue and vortex waveforms, though also with a delay, which denoted the lag between the wall and the flow motion. Clinical diastolic indices combining basal and mitral inflow velocities (E/A ratio and E/ e' ratio) were determined and compared with those measured using a conventional ultrasound scanner; a good correlation was obtained ( r2 = 0.96 ). High-frame-rate Doppler echocardiography enabled us to retrieve time-resolved dynamics of the myocardium and vortex flow within the same cardiac cycle. Coupling wall-flow analysis could be of clinical relevance for early diagnosis of filling impairment.

Measurement of Ultrasound Attenuation for Quantifying Amount ff Fat in Chronic Liver Disease

Several studies about the evaluation of steatosis based on ultrasound attenuation measured by using ultrasound scanners have been reported (Fujii Y. et al, 2002, Kanayama Y. et al, 2013). However, some more investigations seem to be needed toward the practical use. CAP (controlled attenuation parameters), installed in Fibroscan (Echosens) is an example of practical use, but it is not a genre of imaging modality, also requires a dedicated probe. In this study, we tried to measure ultrasound attenuation from B-mode-based RF signals taken by a conventional ultrasound scanner. RF signals for 125 consecutive chronic liver disease (CLD) patients who underwent liver biopsy on the same day were acquired at transmission and reception frequency of 4.0 MHz. Ultrasound scanner used was LOGIQ E9 (GE Healthcare) with a 3.5 MHz convex probe (C1-6-D). Steatosis and liver fibrosis were staged and graded during the pathological analysis of bioptic specimens. Steatosis was categorized as S0: < 5%; S1: 5-33%; S2: 34-66%; or S3: ≥ 67%. Attenuation coefficient (AC) [dB/cm/MHz] of a region of interest (ROI) was measured from the RF signals of the corresponding B-mode image. As the calculation method, first we compensated the envelope of the signal with the reference signals taken from a reference agar-graphite phantom with known attenuation (SONO403, Gammex Inc., 0.5±0.05 dB/cm/MHz). This procedure can eliminate complicity of the beam shape due to the focal ultrasound. Secondly, we measured AC by calculating a slope of the signal envelope compensated. A position of the ROI was selected manually by an operator to avoid the diaphragm or large vessels. The slope was calculated by least squire method. The mean and standard deviation of attenuation coefficient values in steatosis stages S0 (n = 52), S1 (n = 45), S2 (n = 20), and S3 (n = 9) were 0.47±0.08, 0.56±0.08, 0.67±0.06, and 0.73±0.08 dB/cm/MHz, respectively. The mean of AC values demonstrated a stepwise increase with increasing severity of steatosis (P < 0.0001). A significant correlation between AC and the percentage steatosis was found (r = 0.81, P < 0.0001). On the other hand, the mean and standard deviation of AC values in liver fibrosis grades F0 (n = 16), F1 (n = 14), F2 (n = 13), F3 (n = 3), and F4 (n = 21) were 0.49±0.07, 0.47±0.10, 0.46±0.11, 0.50±0.02, and 0.52±0.06 dB/cm/MHz. A significant correlation between AC and the percentage liver fibrosis wasn’t found (r = -0.03, P > 0.5). Attenuation coefficient measured from B-mode-based RF signals demonstrated a stepwise increase with increasing severity of steatosis and had a strong correlation with the percentage steatosis. On the other hand, AC much less correlated with the percentage liver fibrosis. B-mode images are thought to be a good assistance for the measurement. We conclude that our method is useful for a quantifying amount of fat in CLD.

Evaluation of automated breast volume scanner for breast conservation surgery in ductal carcinoma in situ

The present is a retrospective study examining the use of automated breast volume scanner (ABVS) for guiding breast conservation surgery in ductal carcinoma in situ (DCIS). A total of 142 patients with pathologically confirmed DCIS were initially included in the study. The patients underwent preoperative examination by conventional ultrasound and by ABVS. The BI-RADS category system was used to identify benign and malignant lesions, after which breast conservation surgery was performed, and the therapeutic effects were compared. DCIS lesions were found in each quadrant of the breasts. Typical symptoms included: Duct ectasia and filling in 23 cases, mass (mainly solid, occasionally cystic, with or without calcification) in 38 cases, hypoechoic area (with or without calcification) in 33 cases, calcifications (simple) in 23 cases, and architectural distortion in 17 cases. In addition, 110 cases (82.1%) were detected as grade ≥4 according to the BI-RADS category, and 92 cases (68.7%) were considered malignant lesions following conventional ultrasound scanning. The detection rate of ABVS was significantly higher than that of conventional ultrasound (χ2=268.000, P<0.001). The average tumor diameter was 2.5±0.8 cm using ABVS and 2.0±0.9 cm using conventional ultrasound (the former being significantly higher than the latter; t=6.325, P=0.034). Eight patients (5.6%) had recurrences of the cancer, and the tumor diameter in the 8 patients was significantly larger using ABVS as compared to conventional ultrasound. In the diagnosis of DCIS, ABVS was superior to conventional ultrasound scanner in guiding breast conservation surgery and predicting recurrence. However, large-scale studies are required for confirmation of the findings.

Ultrasound Shear Wave Elastography for Liver Disease. A Critical Appraisal of the Many Actors on the Stage.

Ultrasound Shear Wave Elastography for Liver Disease. A Critical Appraisal of the Many Actors on the Stage.

Two-dimensional shear-wave elastography on conventional ultrasound scanners with time-aligned sequential tracking (TAST) and comb-push ultrasound shear elastography (CUSE).

Two-dimensional shear-wave elastography presents 2-D quantitative shear elasticity maps of tissue, which are clinically useful for both focal lesion detection and diffuse disease diagnosis. Realization of 2-D shear-wave elastography on conventional ultrasound scanners, however, is challenging because of the low tracking pulse-repetition-frequency (PRF) of these systems. Although some clinical and research platforms support software beamforming and plane-wave imaging with high PRF, the majority of current clinical ultrasound systems do not have the software beamforming capability, which presents a critical challenge for translating the 2-D shear-wave elastography technique from laboratory to clinical scanners. To address this challenge, this paper presents a time-aligned sequential tracking (TAST) method for shear-wave tracking on conventional ultrasound scanners. TAST takes advantage of the parallel beamforming capability of conventional systems and realizes high-PRF shear-wave tracking by sequentially firing tracking vectors and aligning shear wave data in the temporal direction. The comb-push ultrasound shear elastography (CUSE) technique was used to simultaneously produce multiple shear wave sources within the field-of-view (FOV) to enhance shear wave SNR and facilitate robust reconstructions of 2-D elasticity maps. TAST and CUSE were realized on a conventional ultrasound scanner. A phantom study showed that the shear-wave speed measurements from the conventional ultrasound scanner were in good agreement with the values measured from other 2-D shear wave imaging technologies. An inclusion phantom study showed that the conventional ultrasound scanner had comparable performance to a state-of-the-art shear-wave imaging system in terms of bias and precision in measuring different sized inclusions. Finally, in vivo case analysis of a breast with a malignant mass, and a liver from a healthy subject demonstrated the feasibility of using the conventional ultrasound scanner for in vivo 2-D shear-wave elastography. These promising results indicate that the proposed technique can enable the implementation of 2-D shear-wave elastography on conventional ultrasound scanners and potentially facilitate wider clinical applications with shear-wave elastography.

First report on intraoperative vector flow imaging of the heart among patients with healthy and diseased aortic valves

The vector velocity method Transverse Oscillation (TO) implemented on a conventional ultrasound (US) scanner (ProFocus, BK Medical, Herlev, Denmark) can provide real-time, angle-independent estimates of the cardiac blood flow. During cardiac surgery, epicardial US examination using TO was performed on (A) 3 patients with healthy aortic valve and (B) 3 patients with aortic valve stenosis. In group B, the systolic flow of the ascending aorta had higher velocities, was more aliased and chaotic. The jet narrowed to 44% of the lumen compared to 75% in group A and with a vector concentration, a measure of flow complexity, of 0.41 compared to 0.87 in group A. The two groups had similar secondary flow of the ascending aorta with an average rotation frequency of 4.8Hz. Simultaneous measurements were obtained with spectral Doppler (SD) and a thermodilution technique (TD). The mean difference in peak systolic velocity compared to SD in group A was 22% and 45% in B, while the mean difference in volume flow compared to TD in group A was 30% and 32% in B. TO can potentially reveal new information of cardiac blood flow, and may become a valuable diagnostic tool in the evaluation of patients with cardiovascular diseases.

Low-cost quasi-real-time elastography using B-mode ultrasound images.

A low cost, quasi real-time elastography system, displacement-gradient elastography (DGE), was developed by applying digital image correlation (DIC) method and smoothing algorithm to B-mode ultrasound images. In order to achieve quasi real-time elastogram display, a new fast pattern matching algorithm, decoupled cross-correlation (DCC), was proposed and validated. By applying the DGE to various phantoms, elastograms were generated to identify the lesion with wide variations of stiffness ratio and applied strain. The performance of DGE was qualitatively compared with those from a high-end ultrasound scanner using the elastograms of a commercial elastography breast phantom. DGE was also applied to the ultrasound images of human breast lesions in various BI-RADS categories. This study suggests that DGE may have comparable performance to conventional elastography in detecting breast cancer, while it can be easily implemented onto conventional ultrasound scanners.

Expressiveness of temperature-induced changes in backscattered energy in conventional B-mode images

Changes on conventional B-mode images have been correlated with temperature, aiming to develop a reliable method for noninvasive temperature estimation. The assumption is that temperature variations induce wave propagation changes that modify the backscattered ultrasound signal and these changes have an expression in ultrasonographic images. One of the main effects is the change on the image intensity that is mainly caused by temperature-related changes in backscattered energy (CBE) from tissue inhomogeneities. It is reported that CBE is dependent on medium speed-of-sound and density, behaving in different ways for lipid or aqueous scatterers. In this paper, we demonstrate that CBE has an expression on B-mode images recorded from conventional ultrasound scanners. We observed that different regions have positive, negative, or undefined correlations with temperature, and that this behavior is due to the dependence of CBE with scatterers type. This differentiated behavior enables the segmentation of different structures inside the same tissue. Our experimental setup consisted in the temperature elevation from 36 to 44 °C (hyperthermia range) of ex-vivo tissue samples. We considered bovine muscle and porcine muscle and fat. For both samples, we observed coherent segmentations of the different structures, pointing for a potential clinical application of the proposed analysis.

Optimization of Contrast-to-Tissue Ratio by Adaptation of Transmitted Ternary Signal in Ultrasound Pulse Inversion Imaging

Ultrasound contrast imaging has provided more accurate medical diagnoses thanks to the development of innovating modalities like the pulse inversion imaging. However, this latter modality that improves the contrast-to-tissue ratio (CTR) is not optimal, since the frequency is manually chosen jointly with the probe. However, an optimal choice of this command is possible, but it requires precise information about the transducer and the medium which can be experimentally difficult to obtain, even inaccessible. It turns out that the optimization can become more complex by taking into account the kind of generators, since the generators of electrical signals in a conventional ultrasound scanner can be unipolar, bipolar, or tripolar. Our aim was to seek the ternary command which maximized the CTR. By combining a genetic algorithm and a closed loop, the system automatically proposed the optimal ternary command. In simulation, the gain compared with the usual ternary signal could reach about 3.9 dB. Another interesting finding was that, in contrast to what is generally accepted, the optimal command was not a fixed-frequency signal but had harmonic components.