Conventional Ultrasound Machine Research Articles

Predicting the risk stratification of gastrointestinal stromal tumors using machine learning-based ultrasound radiomics.

This study aimed to use conventional ultrasound features, ultrasound radiomics, and machine learning algorithms to establish a predictive model to assess the risk of post-surgical recurrence of gastrointestinal stromal tumors (GISTs). This retrospective analysis included 230 patients with pathologically diagnosed GISTs. Radiomic features were extracted from manually annotated images. Radiomic features plus conventional ultrasound features were selected using the SelectKbest analysis of variance and stratified tenfold cross-validation recursive elimination methods. Finally, five different machine learning algorithms (logistic regression [LR], support vector machine [SVM], random forest [RF], extreme gradient boosting [XGBoost], and multilayer perceptron [MLP]) were established to predict risk stratification of GISTs. The predictive performance of the established model was mainly evaluated based on the area under the receiver operating characteristic (ROC) curve (AUC) and accuracy, whereas the predictive performance of the optimal machine learning algorithm and a radiologist's subjective assessment were compared using McNemar's test. Seven radiomics features and one conventional ultrasound feature were selected to construct the machine learning models for GIST risk classification. The mentioned five machine learning models were able to predict the malignant potential of GISTs. LR and SVM outperformed other classifiers on the test set, with LR achieving an accuracy of 0.852 (AUC, 0.881; sensitivity, 0.871; specificity, 0.826) and SVM achieving an accuracy of 0.852 (AUC, 0.879; sensitivity, 0.839; specificity, 0.870), and proved significantly better than the radiologist (accuracy, 0.691; sensitivity, 0.645; specificity, 0.813). Machine learning-based ultrasound radiomics features are able to noninvasively predict the biological risk of GISTs.

Cardiac shear wave elastography can detect myocardial remodelling in LBBB patients undergoing CRT

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac shear wave elastography (SWE) allows for the non-invasive assessment of myocardial stiffness via the detection of shear waves travelling through the heart after e.g. mitral valve closure (MVC). The propagation speed of these waves is directly related to myocardial stiffness. Myocardial stiffness depends on the intrinsic properties of the myocardium. Therefore, processes that alter these intrinsic properties, such as cardiac remodelling, could influence shear wave speed. In this way, SWE could be an interesting tool to directly and non-invasively monitor cardiac remodelling over time. Purpose To evaluate the effect of reverse remodelling on myocardial stiffness in left bundle branch block (LBBB) patients undergoing cardiac resynchronization therapy (CRT). Methods Fourteen non-ischemic patients with LBBB undergoing CRT were included. SWE was performed 1 day after CRT implantation and repeated after 6 and 12 months. Eleven age-matched healthy volunteers served as controls. Volumetric response was defined as ≥15% decrease in end-systolic volume after 1 year of CRT. Echocardiographic images were taken during biventricular (BiV) pacing ON (resynchronized) and BiV pacing OFF (native LBBB conduction), both with a conventional ultrasound machine and an experimental high frame rate ultrasound scanner (999 ± 134 frames/s). For SWE, LV parasternal long-axis views were acquired. Shear waves were visualized in M-modes of the septum, colour coded for tissue acceleration. The slope of the shear waves in the M-mode represents their propagation speed (Figure 1A). Results All included patients were volumetric responders. LV ejection fraction and global longitudinal strain improved significantly over time. LV volumes decreased significantly in all patients during one year of CRT (Table 1), reflecting reverse remodelling. Shear wave speed was significantly higher immediately after implantation compared to healthy controls during BiV ON (5.9±1.5 vs 4.6±1.1 m/s; p = 0.02; Figure 1B), but not at 6 months (5.3±1.5 vs 4.6±1.1 m/s; p = 0.19) and 12 months (5.1±1.1 vs 4.6±1.1 m/s; p = 0.39) after implantation (Figure 1B), indicating that myocardial stiffness normalized over time due to reverse remodelling. Moreover, shear wave speed was significantly higher during BiV OFF compared to BiV ON immediately after implantation (5.9±1.5 vs 6.7±1.4 m/s; p = 0.022) and at 6 months (5.3±1.5 vs 6.1±1.4 m/s; p = 0.048), indicating that the reintroduction of dyssynchrony increases shear wave speed after MVC (Figure 1B). One year after implantation shear wave speed was not significantly different between BiV ON and OFF (5.1±1.1 vs 5.2±0.4 m/s; p = 0.78; Figure 1B). This could imply that dyssynchrony decreases over time as a result of reverse remodelling. Conclusion SWE can non-invasively detect changes in myocardial properties during reverse remodelling under CRT. Myocardial stiffness gradually decreases towards the range of age-matched healthy hearts after CRT.

RESEARCH NEW GENERATION ULTRASOUND TECHNOLOGIES IN BLOOD FLOW MONITORING

Currently, ultrasound machines are widely used in hospitals for the first diagnosis of various pathologies. There is also an ultrasound Doppler method to determine and monitor blood flow. Through this method, it is possible to get information about the general condition of the veins and whether there are any problems during the examination of the veins in the clinic. But, it does not have the ability to continuously monitor the condition of the veins. Continuous monitoring of blood flow rate will facilitate the work of doctors during post-operative monitoring or diagnosis of the patient's condition. At the same time, traditional ultrasound transducers may not be comfortable for post-operative examinations. In this article, a number of difficulties encountered during examinations conducted using a conventional ultrasound machine were investigated. At the same time, as a solution to these difficulties, one of the newest technologies of the modern era, the new generation ultrasound machine “USM patch”, its main features and advantages were discussed. This device, based on the working principle of the Doppler effect, is suitable for continuous monitoring of the absolute speed of blood flow in the arteries of the deep layers. It is lightweight, small in size, and has the potential to increase the accuracy and quality of the examination. Keywords: Blood Flow Sensor, movement of red blood cells, Doppler effect, ultrasound machine, Doppler ultrasound patch, biodegradable sensor, automatic

An Automatic Breast Tumor Detection and Classification including Automatic Tumor Volume Estimation Using Deep Learning Technique.

This study aims to develop automatic breast tumor detection and classification including automatic tumor volume estimation using deep learning techniques based on computerized analysis of breast ultrasound images. When the skill levels of the radiologists and image quality are important to detect and diagnose the tumor using handheld ultrasound, the ability of this approach tends to assist the radiologist's decision for breast cancer diagnosis. Breast ultrasound images were provided by the Department of Radiology of Thammasat University and Queen Sirikit Center of Breast Cancer of Thailand. The dataset consists of 655 images including 445 benign and 210 malignant. Several data augmentation methods including blur, flip vertical, flip horizontal, and noise have been applied to increase the training and testing dataset. The tumor detection, localization, and classification were performed by drawing the appropriate bounding box around it using YOLO7 architecture based on deep learning techniques. Then, the automatic tumor volume estimation was performed using a simple pixel per metric technique. The model demonstrated excellent tumor detection performance with a confidence score of 0.95. In addition, the model yielded satisfactory predictions on the test sets, with a lesion classification accuracy of 95.07%, a sensitivity of 94.97%, a specificity of 95.24%, a PPV of 97.42%, and an NPV of 90.91%. An automatic breast tumor detection and classification including automatic tumor volume estimation using deep learning technique yielded satisfactory predictions in distinguishing benign from malignant breast lesions. In addition, automatic tumor volume estimation was performed. Our approach could be integrated into the conventional breast ultrasound machine to assist the radiologist's decision for breast cancer diagnosis.

Handheld versus conventional ultrasound for assessing carotid artery in routine volunteers.

Carotid ultrasound is a key tool for the diagnosis and evaluation of cardio disease, and the measurement of carotid intima-media thickness (CIMT) and hemodynamic parameters is of paramount importance for the imaging method. The aim of this study was to evaluate the feasibility and accuracy of handheld ultrasound devices for measuring carotid parameters. We performed a carotid ultrasound on 25 participants using a handheld ultrasound device and a conventional ultrasound machine. For each participant, max and mean CIMT of common carotid artery (CCA) and peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) of CCA, bilateral external carotid artery (ECA), internal carotid artery (ICA) and the vertebral artery were measured. Agreement and repeatability were evaluated by linear regression and Bland-Altman analysis. We found a good repeatability and consistent of handheld ultrasound device in measuring mean CIMT (r = 0.68, P < 0.01). Furthermore, there was a moderate to good agreement between handheld and conventional ultrasound systems in measuring max IMT, mean IMT, PSV, EDV and RI of CCA (0.73, 0.79, 0.52, 0.58 and 0.84, respectively). Handheld ultrasound devices were able to provide carotid IMT and hemodynamic parameters measurements similar to those of conventional ultrasound. Such capabilities of handheld ultrasound devices might be useful for the primary assessment of carotid in clinical work.

Portable ultrasound technologies for estimating gestational age in pregnant women: a scoping review and analysis of commercially available models

ObjectivesTo identify all available studies assessing the use of portable ultrasound devices for pregnant women, with the specific aim of finding evidence for devices used to determine gestational age and...

Reintroducing dyssynchrony significantly increases myocardial stiffness at mitral valve closure

Abstract Background Cardiac shear wave elastography (SWE) allows for the non-invasive assessment of myocardial stiffness via the detection of shear waves. Shear waves are mechanical waves that travel through the heart after for example mitral valve closure (MVC). The propagation speed of these waves is directly dependent on myocardial stiffness, where a higher shear wave speed correlates with a higher stiffness. However, the effect of a left bundle branch block (LBBB) and a dyssynchronous contraction pattern on shear wave speed is currently unknown. Purpose To investigate the effect of a dyssynchronous contraction pattern caused by LBBB on shear wave speed. Methods We included 29 non-ischemic heart failure patients with an LBBB (68±15y; 52% males) and 9 age-matched healthy volunteers (68±4y; 55% males) as controls. All LBBB patients were implanted with a CRT device and dyssynchrony was reintroduced by turning biventricular (BiV) pacing off to allow native ventricular conduction. Echocardiographic images were taken during BiV pacing on and BiV pacing off, with a conventional ultrasound machine and an experimental high frame rate ultrasound scanner. Shear waves were visualized in M-modes of the septum, colour coded for tissue acceleration. The slope of the shear waves in the M-mode represents their propagation speed. Further, longitudinal strain at MVC and the time difference between onset of septal contraction and MVC were measured (negative time values indicate that MVC occurs before onset of septal contraction). Results There was no significant difference in shear wave speed between healthy controls and LBBB patients during BiV pacing on (4.5±1.1 m/s vs 4.9±1.2 m/s; p=0.365; Figure A). However, shear wave speed was significantly higher in LBBB patients during BiV pacing off compared to healthy controls (4.5±1.1 m/s vs 5.6±1.1 m/s; p=0.041; Figure A). Turning BiV pacing off lead to a significant increase in shear wave speed in LBBB patients (4.9±1.2 m/s vs 5.6±1.1 m/s; p=0.003; Figure A), indicating that the reintroduction of LBBB increases septal myocardial stiffness. MVC occurred significantly later after the onset of septal contraction during BiV pacing off (−9±57 ms vs 40±26 ms; p=0.001) and strain values at MVC were more negative (−0.3±0.6% vs −2.0±1.5%; p&amp;lt;0.001). Therefore we hypothesize that during BiV pacing off, the septal wall was further into the contraction phase at the time of MVC, leading to an increased myocardial stiffness, and thus increased shear wave speed (Figure B). Our interpretation was further strengthened by a strong correlation between the change in shear wave speed and the change in septal longitudinal strain at MVC when BiV pacing is turned off (r=0.81; p&amp;lt;0.001; Figure C). Conclusion Reintroducing dyssynchrony in LBBB patients significantly increases shear wave speed at MVC. Our results suggest that the earlier contraction of the septum during dyssynchrony is an explanation for the higher septal stiffness at MVC. Funding Acknowledgement Type of funding sources: None.

Dyssynchrony significantly increases myocardial stiffness at mitral valve closure

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): FWO: Fonds Wetenschappelijk Onderzoek (fund for Scientific Research Flanders) Background Recently, shear wave elastography (SWE) has emerged as a promising, non-invasive technique to determine myocardial tissue stiffness. SWE is based on the detection of shear waves, for example induced by mitral valve closure (MVC), that propagate through the myocardium. The propagation speed of these shear waves is directly dependent on myocardial stiffness. However, the effect of a dyssynchronous contraction pattern – as it occurs in left bundle branch block (LBBB) – on shear wave speed is currently unknown. Purpose To investigate the effect of the dyssynchronous contraction pattern caused by LBBB on shear wave speed. Methods We included 25 non-ischemic heart failure patients with LBBB (age: 68 ± 15y; 52% males), all implanted with a CRT device. Dyssynchrony was reintroduced by turning biventricular (BiV) pacing off to allow native ventricular conduction. Echocardiographic images were taken during BiV pacing on and BiV pacing off, both with a conventional ultrasound machine and an experimental high frame rate ultrasound scanner (frame rate: 932 ± 32 fps). For SWE, left ventricular parasternal long-axis views were acquired. Shear waves were visualized in M-modes of the septum, colour coded for tissue acceleration. The slope of the shear waves in the M-mode represents their propagation speed. Speckle tracking of the four-chamber apical view was used to asses longitudinal strain of the mid-septal segment. To further investigate how dyssynchrony affects shear wave speed, the following time points were measured: onset of QRS, MVC and onset of septal contraction. Results Acutely switching BiV pacing on and off did not significantly affect left ventricular ejection fraction, nor end-diastolic or end-systolic volumes (all p &amp;gt; 0.05). Shear wave speed was significantly higher during BiV pacing off compared to BiV pacing on (5.6 ± 1.2 m/s vs 4.9 ± 1.3 m/s; p = 0.003; figure A). Furthermore, the onset of septal contraction was significantly earlier during BiV off (11 ± 15 ms vs 105 ± 57 ms; p &amp;lt; 0.0001). As a result, during BiV pacing off, the septal wall was further into the contraction phase at the time of MVC, leading to an increased myocardial stiffness, and thus increased shear wave speed (figure B). Our interpretation that increased shear wave speed could be attributed to an earlier onset of contraction of the septum was further strengthened by a strong correlation between the change in shear wave speed and the change in septal longitudinal strain at MVC when BiV pacing is turned off (r = 0.83; p &amp;lt; 0.001; figure C). Conclusion A dyssynchronous contraction caused by LBBB significantly increases shear wave propagation speed at MVC. This could be attributed to the early-systolic contraction of the septum during dyssynchrony. These results indicate that changes in contraction pattern caused by LBBB significantly influence myocardial stiffness at MVC. Abstract Figure.

Abdominal aorta measurements by a handheld ultrasound device compared with a conventional cart-based ultrasound machine.

BACKGROUND: Ultraportable or pocket handheld ultrasound devices (HUD) may be useful for large-scale abdominal aortic aneurysm screening. However, the reproducibility of measurements has not been compared with conventional cart-based ultrasound machines.OBJECTIVES: Investigate the intra- and inter-operator reproducibility of a HUD compared with a conventional ultrasound machine for aortic screening.DESIGN: Analytical, cross-sectional.SETTING: Ultrasound department at a large tertiary care hospital in Riyadh.PATIENTS AND METHODS: Eligible male participants aged ≥60 years were invited to participate upon arriving for a non-vascular ultrasound appointment. Three repeated anteroposterior measurements of the transverse aorta were made at the proximal and distal locations for each machine before repeating the measurements on a subset of participants by a second blinded operator. Intraclass correlation coefficients (ICC) and the Bland-Altman method were used to analyze reproducibility.MAIN OUTCOME MEASURE: Inter-system and intra- and inter-operator ICCs.SAMPLE SIZE: 114 males with repeated measurements by second operator on a subset of 35 participants.RESULTS: The median age (interquartile range) of participants was 68 years (62–74 years). The intra- and inter-operator ICCs were all >0.800 showing almost perfect agreement except for the inter-operator reproducibility at the proximal location using a conventional machine (ICC= 0.583, P=.007) and the Butterfly device (ICC=0.467, P=.037). The inter-system ICCs (95% CI) were 0.818 (0.736–0.874) and 0.879 (0.799–0.924) at the proximal and distal locations, respectively. The mean difference in aortic measurement between the ultrasound systems was 0.3 mm (1.7%) in the proximal location and 0.6 mm (3.6%) in the distal location. In total, >91% of the difference in measurements between the machines was <3 mm. The mean scanning time was 4:16 minutes for the conventional system and 3:53 minutes for the HUD (P=.34).CONCLUSIONS: Abdominal aortic screening using a HUD was feasible and reliable compared with a conventional ultrasound machine. A pocket HUD should be considered for large-scale screening.LIMITATIONS: No cases of abdominal aortic aneurysm in the sample and lack of blinding.CONFLICT OF INTEREST: None.

Sonographic Evaluation of Hidradenitis Suppurativa with Smartphone-Linked Portable Ultrasound

Background: Clinical staging systems for hidradenitis suppurativa (HS) have poor interrater reliability and may underestimate disease activity. Sonographic staging systems may overcome these challenges, but conventional ultrasound (US) machines are expensive and bulky. Portable (p)US may facilitate the integration of sonography into routine practice. Objectives: To assess the ability of a novel smartphone-linked pUS device to identify key sonographic lesions of HS. Methods: The charts of 16 patients with HS who were assessed with pUS at the outpatient Dermatology and Wound Care Clinics of a university hospital center were retrospectively reviewed. Clinical and sonographic images of the affected areas were examined. The main outcome measures were the number of patients with identifiable sonographic lesions and the number of patients with subclinical lesions detected by pUS. Results: All 3 key sonographic lesions of HS were identifiable with pUS. Sonographic lesions were identified in 10 patients (62.5%). Subclinical lesions were identified in 2 patients (12.5%); in both cases, this affected management decisions. Conclusions: We demonstrate the ability of pUS to identify the key sonographic lesions of HS. pUS is a simple and affordable way to integrate HSUS into clinical and research settings, with clear potential benefits to patients.

The influence of hemodialysis-induced preload changes on the propagation speed of natural shear waves

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation - Flanders (FWO) Background Shear wave elastography (SWE) is a novel ultrasound technique based on the detection of transverse waves travelling through the myocardium using high frame rate echocardiography. The propagation speed of these shear waves is dependent on the stiffness of the myocardium. Previous studies have shown the potential of SWE for the non-invasive assessment of myocardial stiffness. It is unclear, however, if preload changes lead to measurable changes in the shear wave propagation speed in the left ventricle. In patients undergoing hemodialysis, the volume status is acutely changed. In this way, the effect of preload changes on shear wave speed can be assessed. Purpose The aim of this study was to explore the influence of preload changes on end-diastolic shear wave propagation speed. Methods Until now, 6 patients (age: 80[53-85] years; female: n = 2) receiving hemodialysis treatment were included. Echocardiographic images were taken before and every hour during a 4 hour hemodialysis session. Left ventricular parasternal long-axis views were acquired with an experimental high frame rate ultrasound scanner (average frame rate: 1016[941-1310] Hz). Standard echocardiography was performed with a conventional ultrasound machine. Shear waves were visualized on tissue acceleration maps by drawing an M-mode line along the interventricular septum. Shear wave propagation speed after mitral valve closure (MVC) was calculated by measuring the slope of the wave pattern on the acceleration maps (Figure A). Results Over the course of hemodialysis, the systolic (141[135-156] mmHg vs. 165[105-176] mmHg; p = 0.35 among groups) and diastolic blood pressure (70[66-75] mmHg vs. 82[63-84] mmHg; p = 0.21 among groups), heart rate (56[54-73] bmp vs. 57[50-67] bpm; p = 0.76 among groups), E/A ratio (1.6[0.7-1.8] vs. 1.2[0.6-1.4]; p = 0.43 among groups) and E/e’ (14[9-15] vs. 9[8-13]; p = 0.24 among groups ) remained the same. The ultra-filtrated volumes are shown in Figure B. The shear wave propagation speed after MVC gradually decreased during hemodialysis (6.7[5.4-9.7] m/s vs. 4.4[3.6-9.0] m/s; p = 0.04 among groups) (Figure C). There was a moderate negative correlation between shear wave speed and the ultra-filtrated volume (r=-0.63; p &amp;lt; 0.01) (Figure D). Conclusion The shear wave propagation speed at MVC significantly decreased over the course of hemodialysis and correlated to the ultra-filtrated volume. These results indicate that alterations in left ventricular preload affect the speed of shear waves at end-diastole. End-diastolic shear wave speed might therefore be a potential novel parameter for the evaluation of the left ventricular filling state. More patients will be included in the future to further explore these findings. Abstract Figure.

156 Shear wave propagation velocity after aortic valve closure could be a novel parameter for myocardial contractility

Abstract Funding Acknowledgements Research Foundation (FWO) Flanders grant Background Shear wave imaging is a novel ultrasound technique based on the detection of transverse waves travelling through the myocardium by using high frame rate (HFR) echocardiography. These waves can be induced by an external or internal stimulus, such as aortic valve closure (AVC). The propagation velocity of shear waves is directly dependent on myocardial stiffness. It has been previously suggested in animals that the shear wave propagation velocity at AVC might be related to myocardial contractility. Aim The aim of this study was to validate if the shear wave propagation velocity after AVC (end-systole) is related to myocardial contractility. Methods Firstly, 11 healthy volunteers (age: 25 ± 4 years; male: n = 11) performed a supine bicycle exercise test. Images were taken at rest and during 25%, 50% and 66% of maximal workload, as determined by previous upright bicycle exercise testing. Secondly, 9 patients (age: 63 ± 10 years; male: n = 7) underwent a dobutamine stress echocardiography. The stress echo was negative in all patients. Images were taken at rest and after a dobutamine administration of 10µg/kg/min and 40µg/kg/min. Left ventricular (LV) parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) (average frame rate: 1217 ± 233fps). Apical 4-chamber views were acquired with a conventional ultrasound machine. Non-invasive single beat end-systolic elastance (Ees) was used as a measure of contractility. Acceleration maps were created from HFR-datasets by drawing a M-mode line along the midline of the interventricular septum. Shear wave propagation speed at AVC (end-systole) was calculated by measuring the slope of the wave front on the acceleration maps (Figure A). Results During the bicycle exercise, heart rate (61 ± 11bpm vs. 146 ± 13bpm; p &amp;lt; 0.001), systolic blood pressure (125 ± 12mmHg vs. 173 ± 15mmHg; p &amp;lt; 0.001), LV ejection fraction (55 ± 3% vs. 70 ± 5%; p &amp;lt; 0.001), Ees (1.8 ± 0.3mmHg/ml vs. 3.6 ± 1.0mmHg/ml; p &amp;lt; 0.001) and propagation velocity of the shear waves (3.3 ± 0.5m/s vs. 6.2 ± 1.7m/s; p &amp;lt; 0.01) (Figure B) increased significantly from rest to exercise. Likewise, dobutamine administration significantly increased the heart rate (68 ± 10bpm vs. 131 ± 14bpm; p &amp;lt; 0.001), LV ejection fraction (57 ± 5% vs. 74 ± 7%; p &amp;lt; 0.001), as well as the shear wave velocity after AVC (4.4 ± 0.6m/s vs. 7.2 ± 1.7m/s; p &amp;lt; 0.01) (Figure C) and Ees (2.1 ± 0.4mmHg/ml vs. 3.3 ± 0.8mmHg/ml; p &amp;lt; 0.001). Independent from the stressor, shear wave propagation velocity had a good and significant correlation with Ees (Figure D). Conclusion Shear wave propagation velocity after AVC increases with increasing level of exercise or dobutamine dose. Shear wave velocities at AVC show a good correlation with Ees. Our data indicate that end-systolic shear wave velocity is related to myocardial contractility and might therefore be a potential novel parameter for the non-invasive assessment of myocardial function. Abstract 156 Figure.

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats.

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional imaging to study the cardiac anatomy of the left ventricle and M-mode echo to assess its dimensions. However, this could limit a comprehensive study. Herein, we describe a protocol that allows an assessment of the heart chamber size, left ventricular function (systolic and diastolic) and valvular function. A conventional medical ultrasound machine was used in this protocol and different echo views were obtained through left parasternal, apical and suprasternal windows. In the left parasternal window, the long and short axis were acquired to analyze left chamber dimensions, right ventricle and pulmonary artery dimensions, and mitral, pulmonary and aortic valve function. The apical window allows the measurement of heart chamber dimensions and evaluation of systolic and diastolic parameters. It also allows Doppler assessment with detection and quantification of heart valve disturbances (regurgitation or stenosis). Different segments and walls of the left ventricle are visualized throughout all views. Finally, the ascending aorta, aortic arch, and descending aorta can be imaged through the suprasternal window. A combination of ultrasound imaging, Doppler flow and tissue Doppler assessment have been obtained to study cardiac morphology and function. This represents an important contribution to improve the assessment of cardiac function in adult rats with impact for research using these animal models.

A novel gaze-supported multimodal human-computer interaction for ultrasound machines.

Conventional ultrasound (US) machines employ a physical control panel (PCP) as the primary user interface for machine control. This panel is adjacent to the main machine display that requires the operator's constant attention. The switch of attention to the control panel can lead to interruptions in the flow of the medical examination. Some ultraportable machines also lack many physical controls. Furthermore, the need to both control the US machine and observe the US image may lead the practitioners to adopt unergonomic postures and repetitive motions that can lead to work-related injuries. Therefore, there is a need for a more efficient human-computer interaction method on US machines. To tackle some of the limitations with the PCP, we propose to merge the PCP into the main screen of the US machines. We propose to use gaze tracking and a handheld controller so that machine control can be achieved via a multimodal human-computer interaction (HCI) method that does not require one to touch the screen or look away from the US image. As a first step, a pop-up menu and measurement tool were designed on top of the US image based on gaze position for efficient machine control. A comparative study was performed on the BK Medical SonixTOUCH US machine. Participants were asked to complete the task of measuring the area of an ellipse-shaped tumor in a phantom using our gaze-supported HCI method as well as the traditional method. The user study indicates that the task completion time can be reduced by [Formula: see text] when using our gaze-supported HCI, while no extra workload is imposed on the operators. Our preliminary study suggests that, when combined with a simple handheld controller, eye gaze tracking can be integrated into the US machine HCI for more efficient machine control.

Speed-of-Sound Imaging Based on Reflector Delineation.

Speed-of-sound (SoS) has large potential for tissue and pathology differentiation. We aim to develop a novel Ultrasound Computed Tomography (USCT) technique that can reconstruct local SoS in tissue on conventional ultrasound machines with hand-held linear arrays. A passive reflector is placed opposite the tissue sample as an echogenic reference to measure the time-of-flight (ToF) of ultrasound wave- fronts. A Dynamic Programming algorithm provides a robust ToF measurements based on global optimization of all transmit- receive echo data. An Anisotropically-Weighted Total Variation (AWTV) algorithm allows sharp delineation of focal lesions based on limited-angle USCT data. Inclusions, which are not visible in conventional ultrasound, could be delineated in SoS images. AWTV allows to reconstruct focal lesions with a contrast-ratio of 93.7% of their nominal value, compared to that of 31.5% with conventional least-squares based algebraic tomographic reconstruction. In full-wave simulations of realistic heterogeneous breast models, a high CR of 84.3% is observed, with the reconstruction filtering out background heterogeneity. In experiments, our proposed method quantifies SoS in a homogeneous background with an accuracy of 0.93ms, allowing to differentiate several tissue types. We validate our method using numerical simulations with ray-tracing and full- wave models, and phantom and ex-vivo data. Preliminary in- vivo results show the potential of this new technique to detect and differentiate malignant and benign lesions in the breast. Breast cancer is the most common cancer in women. Ultrasound B-mode only provides qualitative information about breast lesions, whereas USCT can provide quantitative tissue imaging biomarkers, such as SoS. The proposed method can potentially be implemented as a complementary modality to ultrasound for tissue and disease differentiation.

The performance of acoustic radiation force impulse imaging in predicting liver fibrosis in chronic liver diseases

Sonography-based noninvasive liver fibrosis assessment is promising in the prediction of treatment efficacy and prognosis in chronic liver disease (CLD) patients. Acoustic radiation force impulse imaging (ARFI) is a newly-developed transient elastography (TE) method integrated into a conventional ultrasound machine. The study aimed to assess the performance of ARFI imaging in the diagnosis of liver fibrosis in Taiwanese CLD patients. We also aimed to search for the optimal cut-off values in different fibrosis stages. A total of 60 CLD patients (40 males; mean age, 51.8±11 years) were consecutively included. They received standard ARFI measurement within 2 weeks at the time of liver biopsy. There were eight patients with Metavir fibrosis stage 0 (F0), 16 patients with F1, 20 patients with F2, eight patients with F3, and eight patients with F4, respectively. The mean values among patient with F0, F1, F2, F3, and F4 were 1.17±0.13, 1.30±0.17, 1.31±0.24, 2.01±0.45, and 2.69±0.91, respectively (p<0.001). The optimal cut-off ARFI value for significant fibrosis (F≥2) was 1.53 with the accuracy of 0.733, while it was 1.66 for advanced fibrosis (F≥3) with the accuracy of 0.957. Our study demonstrated that ARFI imaging is competent for fibrosis diagnosis, particularly in CLD patients with advanced fibrosis.

PTU-086 Suboptimal Performance of Shearwave Elastography (ElastPQ) for Predicting Advanced Fibrosis in a Nafld Enriched Cohort: Abstract PTU-086 Table 1

Introduction It is important to identify those at risk of advanced liver fibrosis in order to stratify care. Histological assessment by liver biopsy (LBx) is the gold standard for staging liver fibrosis, but is impractical for widespread use. Several non-invasive measures of fibrosis, such as transient elastography and simple markers (FIB4 score and AST/ALT ratio (AAR)) have shown promise as alternatives to LBx. Shearwave elastography (SWE), assessed using acoustic radiation force impulses (ARFI), offers a potential alternative technique that can be performed on a conventional ultrasound machine. To date, few studies have evaluated the Phillips ElastPQ system, particularly in patients with non-alcoholic fatty liver disease (NAFLD). Our aim was to evaluate the accuracy of SWE using ElastPQ compared with liver biopsy in a “real world” cohort. Methods Patients undergoing LBx between Sept 2014-Dec 2015 who had SWE conducted at the time of LBx were included. Clinical and demographic data were collected from the time of LBx. The AAR and FIB4 scores were calculated. Liver fibrosis was staged from 0–4; stage 3–4 was considered advanced fibrosis. SWE was conducted by experienced sonographers. SWE values (m/s) were defined as normal ( 1.55). Results 92 patients were identified (52% male; median age 51 yrs, range 20–90). LBx diagnoses were: 57 NAFLD, 10 AIH, 9 PBC, 6 HBV/HCV and 10 other. Median biopsy size was 20 mm (IQR 16.2–24). Overall, there was significant correlation between SWE and fibrosis stage (r = 0.44 p Conclusion In this real world cohort, SWE using ElastPq had suboptimal performance and missed clinically significant advanced fibrosis in 24% of cases. It appears that this technique does not perform as well in patients with NAFLD as other liver diseases, such as viral hepatitis. Disclosure of Interest None Declared

Review of Quantitative Ultrasound: Envelope Statistics and Backscatter Coefficient Imaging and Contributions to Diagnostic Ultrasound.

Conventional medical imaging technologies, including ultrasound, have continued to improve over the years. For example, in oncology, medical imaging is characterized by high sensitivity, i.e., the ability to detect anomalous tissue features, but the ability to classify these tissue features from images often lacks specificity. As a result, a large number of biopsies of tissues with suspicious image findings are performed each year with a vast majority of these biopsies resulting in a negative finding. To improve specificity of cancer imaging, quantitative imaging techniques can play an important role. Conventional ultrasound B-mode imaging is mainly qualitative in nature. However, quantitative ultrasound (QUS) imaging can provide specific numbers related to tissue features that can increase the specificity of image findings leading to improvements in diagnostic ultrasound. QUS imaging can encompass a wide variety of techniques including spectral-based parameterization, elastography, shear wave imaging, flow estimation, and envelope statistics. Currently, spectral-based parameterization and envelope statistics are not available on most conventional clinical ultrasound machines. However, in recent years, QUS techniques involving spectral-based parameterization and envelope statistics have demonstrated success in many applications, providing additional diagnostic capabilities. Spectral-based techniques include the estimation of the backscatter coefficient (BSC), estimation of attenuation, and estimation of scatterer properties such as the correlation length associated with an effective scatterer diameter (ESD) and the effective acoustic concentration (EAC) of scatterers. Envelope statistics include the estimation of the number density of scatterers and quantification of coherent to incoherent signals produced from the tissue. Challenges for clinical application include correctly accounting for attenuation effects and transmission losses and implementation of QUS on clinical devices. Successful clinical and preclinical applications demonstrating the ability of QUS to improve medical diagnostics include characterization of the myocardium during the cardiac cycle, cancer detection, classification of solid tumors and lymph nodes, detection and quantification of fatty liver disease, and monitoring and assessment of therapy.

Assessment of Liver Fibrosis with 2-D Shear Wave Elastography in Comparison to Transient Elastography and Acoustic Radiation Force Impulse Imaging in Patients with Chronic Liver Disease

Two-dimensional shear wave elastography (2-D SWE) is an ultrasound-based elastography method integrated into a conventional ultrasound machine. It can evaluate larger regions of interest and, therefore, might be better at determining the overall fibrosis distribution. The aim of this prospective study was to compare 2-D SWE with the two best evaluated liver elastography methods, transient elastography and acoustic radiation force impulse (point SWE using acoustic radiation force impulse) imaging, in the same population group. The study included 132 patients with chronic hepatopathies, in which liver stiffness was evaluated using transient elastography, acoustic radiation force impulse imaging and 2-D SWE. The reference methods were liver biopsy for the assessment of liver fibrosis (n = 101) and magnetic resonance imaging/computed tomography for the diagnosis of liver cirrhosis (n = 31). No significant difference in diagnostic accuracy, assessed as the area under the receiver operating characteristic curve (AUROC), was found between the three elastography methods (2-D SWE, transient elastography, acoustic radiation force impulse imaging) for the diagnosis of significant and advanced fibrosis and liver cirrhosis in the “per protocol” (AUROCs for fibrosis stages ≥2: 0.90, 0.95 and 0.91; for fibrosis stage [F] ≥3: 0.93, 0.95 and 0.94; for F = 4: 0.92, 0.96 and 0.92) and “intention to diagnose” cohort (AUROCs for F ≥2: 0.87, 0.92 and 0.91; for F ≥3: 0.91, 0.93 and 0.94; for F = 4: 0.88, 0.90 and 0.89). Therefore, 2-D SWE, ARFI imaging and transient elastography seem to be comparably good methods for non-invasive assessment of liver fibrosis.

Feasibility of percutaneous contrast ultrasound-guided cholecystography in dogs.

Differentiating hepatocellular disease versus biliary obstruction can be challenging in dogs presented for icterus. The purpose of this prospective study was to determine the feasibility of percutaneous contrast ultrasound-guided cholecystography in dogs. Ten normal dogs weighing 7.6-13.0 kg (median 9.8 kg) were recruited. All dogs were considered normal based on complete blood count, serum chemistry profile, ultrasound examination, and percutaneous radiographic cholecystography. Percutaneous contrast ultrasound-guided cholecystography was performed using 0.5 ml of commercially available contrast agent and two conventional ultrasound machines for simultaneous scanning at two different locations. Two observers independently evaluated the time to initial detection of contrast in the proximal duodenum and duration of contrast enhancement via visual monitoring. Dynamic contrast enhancement was calculated using time-intensity curves. Mean (± SD) and median (range) of time to initial detection were 8.60 s (± 3.35) and 8.0 s (2.0-11.0), respectively, and mean and median duration were 50.45 s (± 23.24) and 53.0 s (20.0 - 70.0), respectively. Mean, median, and range of peak intensity were 114.1 mean pixel value (MPV) (SD ± 30.7), 109.2 MPV, and 79.7-166.7, respectively, and mean, median, and range of time to peak intensity were 26.1 s (SD ± 7.1 s), 24.0 s, and 19.0-41.0 s, respectively. Findings indicated that percutaneous contrast ultrasound-guided cholecystography is a feasible technique for detecting and quantifying patency of the bile duct in normal dogs. Future studies are needed to assess the diagnostic utility of this technique for dogs with biliary obstruction.