Image quality improvement in single plane-wave imaging using deep learning.

In ultrasound image diagnosis, single plane-wave imaging (SPWI), which can acquire ultrasound images at more than 1000 fps, has been used to observe detailed tissue and evaluate blood flow. SPWI achieves high temporal resolution by sacrificing the spatial resolution and contrast of ultrasound images. To improve spatial resolution and contrast in SPWI, coherent plane-wave compounding (CPWC) is used to obtain high-quality ultrasound images, i.e., compound images, by coherent addition of radio frequency (RF) signals acquired by transmitting plane waves in different directions. Although CPWC produces high-quality ultrasound images, their temporal resolution is lower than that of SPWI. To address this problem, some methods have been proposed to reconstruct a ultrasound image comparable to a compound image from RF signals obtained by transmitting a small number of plane waves in different directions. These methods do not fully consider the properties of RF signals, resulting in lower image quality compared to a compound image. In this paper, we propose methods to reconstruct high-quality ultrasound images in SPWI by considering the characteristics of RF signal of a single plane wave to obtain ultrasound images with image quality comparable to CPWC. The proposed methods employ encoder-decoder models of 1D U-Net, 2D U-Net, and their combination to generate the high-quality ultrasound images by minimizing the loss that considers the point spread effect of plane waves and frequency spectrum of RF signals in training. We also create a public large-scale SPWI/CPWC dataset for developing and evaluating deep-learning methods. Through a set of experiments using the public dataset and our dataset, we demonstrate that the proposed methods can reconstruct higher-quality ultrasound images from RF signals in SPWI than conventional method.

Singular value decomposition with weighting matrix applied for optical-resolution photoacoustic microscopes.

The prestige target selectivity and imaging depth of optical-resolution photoacoustic microscope (OR-PAM) have gained attentions to enable advanced intra-cellular visualizations. However, the broad-band nature of photoacoustic signals is prone to noise and artifacts caused by the inefficient light-to-pressure translation, resulting in poor image quality. The present study foresees application of singular value decomposition (SVD) to effectively extract the photoacoustic signals from these noise and artifacts. Although spatiotemporal SVD succeeded in ultrasound flow signal extraction, the conventional multi frame model is not suitable for data acquired with scanning OR-PAM due to the burden of accessing multiple frames. To utilize SVD on the OR-PAM, this study began with exploring SVD applied on multiple A-lines of photoacoustic signal instead of frames. Upon explorations, an obstacle of uncertain presence of unwanted singular vectors was observed. To tackle this, a data-driven weighting matrix was designed to extract relevant singular vectors based on the analyses of temporal-spatial singular vectors. Evaluation on the extraction capability by the SVD with the weighting matrix showed a superior signal quality with efficient computation against past studies. In summary, this study contributes to the field by providing exploration of SVD applied on A-line signals as well as its practical utilization to distinguish and recover photoacoustic signals from noise and artifact components.

Quantitative evaluation of adhesion severity around subscapularis and its relationship with shoulder range of motion in frozen shoulder and rotator cuff disorder: an observational study using dynamic ultrasonography.

Background: This study aimed to evaluate the severity of adhesion between muscles in the shoulder joint using dynamic ultrasonography and to confirm whether adhesions cause range of motion (ROM) restrictions. Methods: Twenty-four shoulders from 15 frozen shoulder patients and 24 shoulders from 18 rotator cuff disorder patients were enrolled. We obtained ultrasound video sequences of the subscapularis (SSC) and deltoid muscles during shoulder external rotation. The mean stretching velocities of the deltoid and SSC were subsequently analyzed using a personal computer. If adhesions occurred between both muscles, the deltoid was stretched more vigorously, and we calculated mean stretching velocity of the deltoid / SSC as adhesion severity. The coracohumeral ligament thickness was measured using the same images. Shoulder ROM was measured by using a universal goniometer. Results: The intraclass correlation coefficients (1.1) and (2.1) of the adhesion severity measurements were 0.85 and 0.91, respectively. Multiple linear regression analysis revealed that the adhesion severity is a significant predictor for external rotation ROM in the rotator cuff disorder group (R2 = 0.44, F = 10.1, P < .01, t = -2.9), while coracohumeral ligament thickness predicts ROM in the frozen shoulder group (R2 = 0.28, F = 5.5, P = .01, t = -3.0). Conclusion: The proposed method is reliable. Muscle adhesion causes ROM restriction of the shoulder joint. The primary cause of shoulder ROM restriction differed between the diagnostic groups.

Opportunistic Ultrasound Screening for Abdominal Aortic Aneurysm.

Objective: In patients with abdominal aortic aneurysm (AAA), early detection and optimal elective treatment before rupture are desirable. In the absence of an established public screening system, opportunistic screening during ultrasound examination for another purpose might be efficacious. The aim of this study was to evaluate the efficacy of opportunistic screening for AAA. Methods: This prospective multicenter observational study enrolled patients who were scheduled to undergo ultrasound for reasons other than AAA. After the ultrasound for the original purpose, evaluation of the abdominal aorta was added. If the abdominal aorta was clear enough for measurement, its diameter and shape were recorded. Furthermore, information on comorbidities was collected for each patient. Results: A total of 10325 patients (echocardiography: 6150; abdominal ultrasound: 4162) from 16 institutions were enrolled. The abdominal aorta was well visualized in 92.9% of patients who underwent echocardiography. Among 9791 patients, AAA was diagnosed in 122 (1.3%) (107 fusiform and 15 saccular), with a diameter range of 30-63 mm. The diagnostic rate increased with age. On multivariate analysis, older age, male sex, coronary artery disease, peripheral arterial disease, and smoking habituation were the risk factors for AAA. Conclusion: Opportunistic screening for AAA was efficacious.

Transrectal ultrasound vector projectile imaging for time-resolved visualization of flow dynamics in the male urethra: A clinical pilot study.

BACKGROUND: Quantitative and comprehensive visualization of urinary flow dynamics in the urethra is crucial for investigating patient-specific mechanisms of lower urinary tract symptoms (LUTS). Although some methods can evaluate the global properties of the urethra, it is critical to assess the local information, such as the location of the responsible lesion and its interactions with urinary flow in relation to LUTS. This approach is vital for enhancing personalized and focal treatments. However, there is a lack of such diagnostic tools that can directly observe how the urethral shape and motion impact urinary flow in the urethra. PURPOSE: This study aimed to develop a novel transrectal ultrasound imaging modality based on the contrast-enhanced urodynamic vector projectile imaging (CE-UroVPI) framework and validate its clinical applicability for visualizing time-resolved flow dynamics in the urethra. METHODS: A new CE-UroVPI system was developed using a research-purpose ultrasound platform and a custom transrectal linear probe, and an imaging protocol for acquiring urodynamic echo data in male patients was designed. Thirty-four male patients with LUTS participated in this study. CE-UroVPI was performed to acquire ultrasound echo signals from the participant's urethra and urinary flow at various voiding phases (initiation, maintenance, and terminal). The ultrasound datasets were processed with custom software to visualize urinary flow dynamics and urethra tissue deformation. RESULTS: The transrectal CE-UroVPI system successfully visualized the time-resolved multidirectional urinary flow dynamics in the prostatic urethra during the initiation, maintenance, and terminal phases of voiding in 17 patients at a frame rate of 1250 fps. The maximum flow speed measured in this study was 2.5 m/s. In addition, when the urethra had an obstruction or an irregular partial deformation, the devised imaging modality visualized complex flow patterns, such as vortices and flow jets around the lesion. CONCLUSIONS: Our study findings demonstrate that the transrectal CE-UroVPI system developed in this study can effectively image fluid-structural interactions in the urethra. This new diagnostic technology has the potential to facilitate quantitative and precise assessments of urethral voiding functions and aid in the improvement of focal and effective treatments for patients with LUTS.

Ultrasound vector flow imaging during veno-arterial extracorporeal membrane oxygenation in a thoracic aorta model.

In veno-arterial extracorporeal membrane oxygenation (VA-ECMO) treatment, the mixing zone is a key hemodynamic factor that determines the efficacy of the treatment. This study aimed to evaluate the applicability of a novel ultrasound technique called vector flow imaging (VFI) for visualizing complex flow patterns in an aorta phantom under VA-ECMO settings. VFI experiments were performed to image aortic hemodynamics under VA-ECMO treatment simulated in an anthropomorphic thoracic aorta phantom using a pulsatile pump (cardiac output: 2.7 L/min) and an ECMO pump with two different flow rates, 0.35 L/min and 1.0 L/min. The cardiac cycle of hemodynamics in the ascending aorta, aortic arch, and descending aorta was visualized, and the spatio-temporal dynamics of flow vectors were analyzed. VFI successfully visualized dynamic flow patterns in the aorta phantom. When the flow rate of the ECMO pump increased, ECMO flow was more dominant than cardiac output in the diastole phase, and the speed of cardiac output was suppressed in the systole phase. Vortex flow patterns were also detected in the ascending aorta and the arch under both ECMO flow rate conditions. The VFI technique may provide new insights into aortic hemodynamics and facilitates effective and safe VA-ECMO treatment.

Utilization of Curvelet Transform in Reconstructing Cellular Images for Undersampled Optical-Resolution Photoacoustic Microscopy.

We address the problem of limited temporal resolution in optical-resolution microscopy (OR-PAM) for cellular imaging by undersampling and reconstruction. A curvelet transform method in a compressed sensing framework (CS-CVT) was devised to specifically reconstruct the boundary and separability of cell objects in an image. The performance of the CS-CVT approach was justified by comparisons with the natural neighbor interpolation (NNI) followed by smoothing filters on various imaging objects. In addition, a full-raster scanned image was provided as a reference. In terms of structure, CS-CVT produces cellular images with a smoother boundary but less aberration. We found the strength of CS-CVT in recovering high frequency that is important in representing sharp edges which often missing in typical smoothing filters. In a noisy environment, CS-CVT was less affected by the noise compared to NNI with a smoothing filter. Furthermore, CS-CVT could attenuate noise beyond the full raster scanned image. By considering the finest structure in the cellular image, CS-CVT was performing well with a minimum range of undersampling around 5% to 15%. In practice, this undersampling was easily translated into 8- to 4-fold faster OR-PAM imaging. In summary, our approach improves the temporal resolution of OR-PAM without a significant tradeoff in image quality.

Evaluation of temperature-dependent fluctuations in skin microcirculation flow using a light-emitting diode based photoacoustic imaging device.

PURPOSE: Skin microvessels maintain temperature homeostasis by contracting and dilating upon exposure to changes in temperature. Under general anesthesia, surgical invasiveness, including incisions and coagulation, and the effects of anesthetics may cause variations in the threshold temperature, leading to the constriction and dilation of cutaneous blood vessels. Therefore, studies on skin microvascular circulation are necessary to develop appropriate interventions for complications during surgery. METHODS: We visualized and quantified skin microcirculatory fluctuations associated with temperature variations using a light-emitting diode photoacoustic imaging (LED-PAI) device. The hands of ten healthy volunteers were stressed with four different water temperatures [25℃ (Control), 15℃ (Cold1), 40℃ (Warm), and 15℃ (Cold2)]. The photoacoustic images of the fingers were taken under each condition, and the microvascular flow owing to temperature stress was quantified as the area of photoacoustic signal (S) in each image. The S values were compared with the variations in blood flow (Q) measured by laser Doppler flowmetry (LDF). RESULTS: The correlation between Q and S according to the 40 measurements was r = 0.45 (p＜0.01). In addition, the values of S under each stress condition were as follows: Scontrol = 10,826 ± 3364 pixels, Scold1 = 8825 ± 2484 pixels, Swarm = 13,369 ± 3001 pixels, and Scold2 = 8838 ± 1892 pixels; the differences were significant. The LDF blood flow (Q) showed similar changes among conditions. CONCLUSION: These findings suggest that the LED-PAI device could be an option for evaluating microcirculation in association with changes in temperature.

Extracorporeal shockwave therapy in an immobilized knee model in rats prevents progression of joint contracture.

Joint immobilization, which ensures rest and accelerates tissue recovery in musculoskeletal disorders, often causes joint contracture, for which there is still no effective prevention. To address this, we investigated the effects of extracorporeal shockwave therapy (ESWT) in preventing joint contracture, in a unilaterally immobilized knee rat model. Under general anesthesia, ESWT (0.25 mJ/mm2 , 3000 shot, 4 Hz, 3 days/week) was administered from 1 day after immobilization up to 2, 4, and 6 weeks. The immobilized control group received general anesthesia without ESWT. We evaluated joint angle, tissue elasticity, and gene and protein expression related to fibrosis, inflammation, and angiogenesis in the joint capsule. Relative to the control, the ESWT group had greater joint angle at 4 and 6 weeks, and lower posterior-capsule elasticity at 6 weeks. In the ESWT group, at 6 weeks, gene expression of collagen type I (col1α1), connective tissue growth factor (CTGF), and α-smooth muscle actin (α-SMA) was significantly downregulated, whereas interleukin-6 (IL-6) and hypoxia-inducible factor-1α (HIF-1α) gene expression was upregulated, relative to that in the control. Compared with that in the control, at 4 and 6 weeks, the ratio of CTGF+ cells was significantly lower in the ESWT group; at 4 weeks, the ESWT group had significantly fewer CD68+ cells in the adhesion area, and at 6 weeks, significantly more blood vessels. Statement of Clinical Significance: In a rat model, ESWT counteracted fibrosis, suppressed macrophage infiltration, and promoted neovascularization, reducing elasticity, and increasing joint range-ofmotion. ESWT offers a potential new strategy to prevent progression in joint contracture.

Region-based SVD processing of high-frequency ultrafast ultrasound to visualize cutaneous vascular networks.

Observing alterations in cutaneous vasculature in response to any disease or pathology is considered as a potential diagnostic marker in the progression and cure of a disease. To observe skin morphologies and tissue conditions, high-frequency ultrasound (HFUS) has been used in dermatology, although its ability to selectively visualize micro-vessels is limited due to insufficient Doppler sensitivity to peripheral slow-speed blood flow. In recent studies, this issue has been improved by increasing the sensitivity of Doppler imaging to slow flow, leveraging advanced cutter filtering approaches based on singular value decomposition (SVD) techniques that aid to effectively extract flow signals overlapped with tissue echo signals. Nevertheless, in skin imaging, variations in flow speed, diameter, and depth of the blood vessels at different skin layers can make clutter filtering challenging because these variations are problematic in selecting the optimal cut-off value for the SVD filtering. In this study, we aimed to devise a novel region-based SVD filtering approach for ultrafast HFUS data to visualize cutaneous vascular networks. The proposed method divides the acquired high-framerate data into two regions based on B-mode cutaneous morphological identification (dermis layer and subcutaneous tissue). Singular value decomposition processing was performed on each region to effectively extract the desired flow signal, and the processed regions were merged to generate a single power Doppler image, thereby highlighting the appearance of a complete cutaneous vascular network. Finally, top-hat transform was applied to the power Doppler image to further suppress the background noises and enhances the visibility of the micro-vessels. Experimental observations of the human cutaneous circulation showed that the image quality (contrast-to-noise ratio) through the region-based SVD filtering was measured to be 4.1 dB (before top-hat filtering) and 5.2 dB (after top-hat filtering), which were improved from 3.4 dB and 4.0 dB obtained using the global SVD approach with and without top-hat filtering, respectively. We envisioned that this approach would provide diverse applications in the diagnosis of cutaneous disorders.

Development of an Imaging Framework for Visualization of Cutaneous Micro-Vasculature by using High Frequency Ultrafast Ultrasound Imaging.

Visualization of cutaneous micro-vasculatures is a determined approach in the diagnosis of skin vascular disorders. Clinically, high frequency ultrasound (HFUS) modalities have been used for cutaneous morphological and structural imaging, but visualization of micro-vessels has always been remained a daunting task. These tiny structures might be visualized by devising a highly sensitive Doppler technique for HFUS systems. In this study, we proposed an imaging framework using HFUS (30 MHz) ultrafast Doppler imaging along with SVD clutter filtering that is proficient in detection of micro-scale circulation. The performance of the devised framework was examined on a 200-micron flow phantom made of poly-vinyl alcohol under four different flow rates (56 - 18 ul/min) and visualized the micro-structure with averaged detected diameter of 93 - 170 µm. The results indicated that the devised framework has sufficient sensitivity and resolvability to visualize the micro-vasculatures in dermis layer of skin (depth ≤ 4 mm). Clinical Relevance - This study brings an insight to visualize in-vivo cutaneous micro-vasculatures with ultrafast Doppler imaging in clinical applications for better assessment of cutaneous disorders.

The effects of hydroxyethyl starch 130/0.4 on perioperative renal function in patients undergoing cardiac surgery: A randomised controlled trial.

Background: Acute kidney injury (AKI) after cardiac surgery increases the risk of morbidity and mortality. Hydroxyethyl starch (HES) is often used during surgery due to its plasma-volume expanding effect, but the impact of HES 130/0.4 on renal function in patients undergoing cardiac surgery remains unclear. The aim of our study is to investigate the impact of HES 130/0.4 on postoperative renal function in patients undergoing cardiac surgery using cardiopulmonary bypass. Methods: Our study was a randomised, single-center, single-blind study conducted on 60 adult patients who underwent cardiac surgery using cardiopulmonary bypass: 30 patients were intraoperatively administered with HES 130/0.4; the other 30 with Ringer's bicarbonate. The primary endpoints were occurrence of AKI within 30 days of surgery and the disease stages. Results: The mean dose of 6% HES 130/0.4 was 28 ml/kg. AKI occurred within 30 days of the operation in 8 cases (28.6%) in the HES group and 6 cases (21.4%) in the crystalloid group (no significance: p = 0.5371). Disease stages were as follows: "no AKI", "stage 1", "stage 2″ and "stage 3″, accounting for 20 cases (71.5%), 6 cases (21,4%), 2 cases (7.1%), and 0 cases, respectively, in the HES group, and 22 cases (78.6%), 6 cases (21.4%), 0 cases, and 0 cases, respectively, in the crystalloid group (no significance: p = 0.3508). Conclusion: There was no significant difference in the occurrences or stages of AKI during the 30 days following cardiac surgery with cardiopulmonary bypass between patients administered with HES 130/0.4 or Ringer's bicarbonate.

High-speed optical resolution photoacoustic microscopy with MEMS scanner using a novel and simple distortion correction method.

Optical resolution photoacoustic microscopy (OR-PAM) is a remarkable biomedical imaging technique that can selectively visualize microtissues with optical-dependent high resolution. However, traditional OR-PAM using mechanical stages provides slow imaging speed, making it difficult to biologically interpret in vivo tissue. In this study, we developed a high-speed OR-PAM using a recently commercialized MEMS mirror. This system (MEMS-OR-PAM) consists of a 1-axis MEMS mirror and a mechanical stage. Furthermore, this study proposes a novel calibration method that quickly removes the spatial distortion caused by fast MEMS scanning. The proposed calibration method can easily correct distortions caused by both the scan geometry of the MEMS mirror and its nonlinear motion by running an image sequence only once using a ruler target. The combination of MEMS-OR-PAM and distortion correction method was verified using three experiments: (1) leaf skeleton phantom imaging to test the distortion correction efficacy; (2) spatial resolution and depth of field (DOF) measurement for system performance; (3) in-vivo finger capillary imaging to verify their biomedical use. The results showed that the combination could achieve a high-speed (32 s in 2 × 4 mm) and high lateral resolution (~ 6 µm) imaging capability and precisely visualize the circulating structure of the finger capillaries.

Usefulness of Right Ventricular Free Wall Strain Obtained with Two-Dimensional Speckle-Tracking Echocardiography in Patients with Repaired Tetralogy of Fallot and Pulmonary Regurgitation.

Right ventricular (RV) dysfunction caused by chronic pulmonary regurgitation (PR) is a major determinant of clinical outcome in adults with repaired tetralogy of Fallot (rTOF). However, the accurate assessment of RV function by conventional echocardiography remains challenging. This study tested the feasibility and usefulness of RV free-wall (RVFW) strain obtained by two-dimensional (2D) speckle-tracking echocardiography (STE) in evaluation of RV function in adults with rTOF by comparing cardiac magnetic resonance (CMR) imaging. We enrolled 22 consecutive patients (male/female, 8/14; mean age, 25.0 years) with rTOF who underwent transthoracic echocardiography at Tohoku University Hospital from July 2016 to June 2019. We measured RVFW strain by STE and compared them with 22 hemodynamically normal subjects (NOR) (male/female, 9/13; mean age, 32.0 years). The correlation between RV strain and CMR-derived RV ejection fraction (RVEF) or PR fraction (PRF) were also evaluated. All rTOF patients had more than moderate PR but were near asymptomatic. RVFW longitudinal strain (RVFW-LS) was significantly decreased in the rTOF group compared with that in the NOR group (-19.6 vs. -24.7, P < 0.01). In the rTOF group, RVFW-LS correlated with PRF (r = 0.44, P < 0.05), whereas RVFW circumferential strain at the mid-ventricular level correlated with RVEF (r = 0.57, P < 0.01). Intra-observer variability of RVFW strain was acceptable. These results indicate that RV systolic function and PR severity in rTOF could be assessed by RVFW strain measured by 2D STE. This method is feasible and can be used as a complement to CMR imaging.

Color Doppler shear wave elastography using commercial ultrasound machine with compensated transducer scanning delay.

PURPOSE: Tissue elasticity can be measured and mapped using color Doppler elastography. In a previous study, a binary pattern of shear waves was observed using a color flow imaging (CFI) system with matched pulse Doppler packet size as well as shear wave frequency and displacement condition. In the present study, we demonstrate the possibility of mapping shear wave velocity and resolving phantom elasticity using any commercial ultrasound machine without fulfilling that condition. METHODS: We derive a relation between Doppler autocorrelator integration time and the estimated flow velocity. The underlying principles behind the shear wave shadows captured by a typical modern ultrasound machine are investigated. The ultrasound machine measurement preset is calibrated to remove the effect of transducer array scanning delay in modifying the appearing wavenumber and thus correct the measurement error. RESULTS: The method was used to successfully measure the elasticity of a biological tissue-mimicking phantom and distinguish a stiff phantom from a soft phantom. CONCLUSION: Using this method, the elasticity of a biological tissue-mimicking phantom can be recovered with less strict constraint. As a result, it provides more flexibility to be implemented in common ultrasound machines. This method may be practically used to help identify tissue stiffness-related disease.

Binary Pattern Color Doppler Shear Wave Elastography.

Some studies suggested a correlation between tissue elasticity and diseases, such as Adhesive Capsulitis (AC) of the shoulder. One category of method to measure elasticity is by utilizing Doppler imaging. This paper discusses color Doppler shear wave elastography methods and demonstrated an experiment with biological tissue mimicking phantom. A simulation with binary pattern color Doppler shear wave elastography shows that wavelength of a shear wave with suggested magnitude is equal to four multiple of pitch strip in a color flow image. However, the larger amplitude changes the duty ratio and frequency of the pattern. An experiment with biological tissue mimicking Polyvinyl Alcohol (PVA) phantoms has shown that the binary pattern color Doppler method has successfully recovered shear wave velocity map and calculate the elasticity.Clinical Relevance-The result of experiments presents a possibility of using the method for quantitatively access the stage of tissue stiffness related disease.

A histoanatomical study of the fiber bundle forming the 'Comma Sign,' a critical marker of the torn edge of the subscapularis tendon.

INTRODUCTION: The "Comma sign" is a well-known indicator of the subscapularis torn edge of the shoulder. We undertook a histoanatomical study of the fiber bundle forming Comma sign (FBCS) to determine why FBCS is maintained even in cuff tear cases. MATERIALS AND METHODS: Part 1: five tissue blocks including the supraspinatus tendon (SSP), rotator interval (RI), and subscapularis tendon (SSC) out of 5 cuff-intact cadavers were histologically observed in serial sections. Part 2: another tissue blocks of 6 cuff-intact cadavers were serially sectioned along the estimated FBCS direction based on the Part 1 findings. Additionally, 5 tissue blocks of cuff-torn cadavers including the three components, SSP, FBCS, and SSC, were serially sectioned along the apparent FBCS. In one slice clearly demonstrating FBCS fibers out of each section series, the components were measured of the sound speed and visualized through a scanning acoustic microscope (SAM). RESULTS: At the lateral portion, RI tissue with the joint capsule became thick and tightly surrounded SSP. Similarly, thicker RI tissue adhered to SSC from the superior and bursal side. More laterally, the borders of SSP/FBCS and FBCS/SSC were unclear with intermingled fibers. At the lateral most portion, RI tissue formed a fiber bundle, FBCS, extending from SSP to the bursal side of SSC. The sound speeds of SSP and SSC were significantly faster than FBCS in both cuff-intact and cuff-torn slices. In SAM images of cuff-torn specimens the FBCS borders were all unclear. CONCLUSIONS: As FBCS extends from the capsule beneath SSP and to the bursal surface of SSC, the FBCS connection to SSP and SSC is hardly lost, even though SSP or SSC detaches from the greater or lesser tubercle, respectively. Additionally, as degeneration make the elasticity difference gradual, the stress concentration at the borders may be diminished, leading to less breakage of FBCS.

Visualization of Shoulder Ligaments Motion by Ultrasound Speckle Tracking Method.

There is no unified consensus on the pathophysiology of adhesive capsulitis which is also called as frozen shoulder. Some studies have suggested that coracohumeral ligament (CHL) played an important role in adhesive capsulitis. These studies showed relation between disease prevalence and CHL thickness by means of ultrasound or MRI. Other possible etiology of the disease is the adhesion of shoulder ligament with each other. In the present study, shoulder ligaments motion is visualized with velocity vector by speckle tracking and temporal outlier removal algorithm to process ultrasound movie during forced movement of shoulder joint. The measurement with a typical subject has demonstrated an improvement of velocity vector deviation of up to 43% by the proposed outlier removal technique.

Validation of Echodynamography in Comparison with Particle-image Velocimetry.

Echodynamography (EDG) is a computational method to estimate and visualize two-dimensional flow velocity vectors by applying dynamic flow theories to color Doppler echocardiography. The EDG method must be validated if applied to human cardiac flow function. However, a few studies of flow estimated have compared by EDG to the flow data were acquired by other methods. In this study, EDG was validated by comparing the analysis of estimating and visualizing flow velocity vectors obtained by original particle image velocimetry (PIV) based on a left ventricular (LV) phantom hydrogel (in vitro studies) and by EDG based on the virtual Doppler velocity. Velocity measured by PIV method and velocity estimated by EDG method in the perpendicular direction and the radial direction were compared. Regression analysis for the velocity estimated in the radial direction revealed an excellent correlation (R2=0.99, slope = 0.96) and moderate correlation in the perpendicular direction (R2=0.44, slope = 0.46). As revealed by the Bland-Altman plot, however, overestimations and higher relative error were observed in the perpendicular direction (0.51 ± 2.75 mm/s) and in the radial direction (-2.15 ± 21.13 mm/s). The percentage error of the norm-wise relative error of the velocity discrepancy is less than 10%, and velocity magnitude followed the same trends and are of comparable magnitude. These findings indicate that good estimates of velocity can be obtained by the EDG method. Therefore, the EDG method was appropriate for estimating and visualizing velocity vectors in clinical studies for higher measurement accuracy and reliability. The clinical in vivo application showed that the EDG method has the ability to visualize blood flow velocity vectors and differentiate the clinical information of vortex parameters both in normal and abnormal LV subjects. In conclusion, the EDG method has potentially greater clinical acceptance as a tool assessment of LV during the cardiac cycle.