Acoustic Window Research Articles

Sonographic Assessment of Placenta Previa with and without History of Cesarean Section or Abortion

Background: The incidence of placenta Previa has increased with increasing maternal age due to late marriages. Objective: To assess occurrence of placenta Previa in females with and without history of C- section, abortion and both. Methodology: Descriptive cross sectional study conducted in Sir Ganga Ram Hospital Lahore, radiology department. Duration of study was nine months after the approval of synopsis. Main aim was to assess occurrence of placenta Previa in females with and without history of C-section and abortion or both. The examination will start with the patient in the supine position (3.5 – 5 MHz) convex probe will be used .From the anteriorly using urinary bladder as acoustic window ultrasound will be performed in the longitudinal planes. In Transabdominal study (TAS) the bladder will be adequately distended to visualization of the cervix and lower uterine segment and to check the relationship of the placenta to the inner os. If indicated, positioning the patient in a right or left posterior oblique position may be helpful to check the posterior placenta. The diagnosis of placenta Previa will be considered if the lower placental edge covers the internal os.

Left atrial strain determinants and clinical features according to the heart failure stages. New insight from EACVI MASCOT registry

Few studies analyzed left atrial (LA) peak atrial longitudinal strain (PALS) determinants, particularly across heart failure (HF) stages. We aimed to analyze the pathophysiological and clinical PALS correlates in a large multicentric prospective study. This is a multicenter prospective observational study enrolling 745 patients with HF stages. Data included PALS and left ventricular global longitudinal strain (LV-GLS). Exclusion criteria were: valvular prosthesis; atrial fibrillation; cardiac transplantation; poor acoustic window. Median global PALS was 17% [24–32]. 29% of patients were in HF-stage 0/A, 35% in stage-B, and 36% in stage-C. Together with age, the echocardiographic determinants of PALS were LA volume and LV-GLS (overall model R2 = 0.50, p < 0.0001). LV-GLS had the strongest association with PALS at multivariable analysis (beta: −3.60 ± 0.20, p < 0.0001). Among HF stages, LV-GLS remained the most important PALS predictor (p < 0.0001) whereas age was only associated with PALS in lower HF-stage 0/A or B (R = − 0.26 p < 0.0001, R = − 0.23 p = 0.0001). LA volume increased its association to PALS moving from stage 0/A (R = − 0.11; P = 0.1) to C (R = − 0.42; P < 0.0001). PALS was the single most potent echocardiographic parameter in predicting the HF stage (AUC for B vs. 0/A 0.81, and AUC vs. 0/A for C 0.76). PALS remained independently associated with HF stages after adjusting for ejection fraction, E/e′ ratio, and mitral regurgitation grade (p < 0.0001). Although influenced by LV-GLS and LA size across HF stages, PALS is incrementally and independently associated with clinical status. LA function may reflect a substantial part of the hemodynamic consequences of ventricular dysfunction.

442 Myocardial Work Estimation With Ct Aids Evaluation Of Regional Right Ventricular Function

Introduction: Myocardial work (MW) - the area of the myocardial stress-strain loop - can serve as a better metric of myocardial performance than volumetric or strain measures, as MW is independent of loading conditions and has been shown to reflect regional oxygen perfusion and glucose metabolism. In practice, MW has been estimated as the ventricular pressure-myocardial strain area (PSA) using echocardiography. However, the RV’s complex geometry and echo’s limited acoustic windows can limit this approach.

THE ROLE OF TRANSCRANIAL ULTRASOUND IN THE EVALUATION OF HYPOXIC ISCHEMIC ENCEPHALOPATHY

Introduction: Hypoxic ischemic encephalopathy is a clinical term used to describe an abnormal neurobehavioral state that consists of a decreased level of consciousness with abnormalities in neuromotor tone. Any neonate, regardless of birth weight, size, or gestational age, who has a greater than average chance of morbidity or mortality, due to fetal, maternal or placental anomalies or an otherwise compromised pregnancy especially within the first 28 days of life is categorized as high-risk neonate. Cranial ultrasonography plays an important role in the diagnosis of significant lesions in infants presenting with hypoxic ischemic encephalopathy (HIE) and seizures and assessing severity, neurodevelopment outcome and neurological prognosis of these high-risk infants. In the neonate, many sutures and fontanelles are still open and these can be used as acoustic windows to look into the brain. Methodology: This was a hospital based descriptive observational study of 100 preterm and term babies with suspected brain injuries who were referred for cranial USG examination to the Radiodiagnosis Department of R.N.T. Medical College, Udaipur with hypoxic ischemic encephalopathy over a period of 18 months from June 2020 to November 2021. Results:The most common affected age group was 32-37weeks (51%). The abnormalities found on neurosonogram were germinal matrix hemorrhage, periventricular leucomalacia, cystic PVL, cerebral edema and ventriculomegaly. The most common abnormality was germinal matrix hemorrhage (17%) and subependymal hemorrhage (41%) was most common type. Isolated ventriculomegaly (53.8%) was more common than ventriculomegaly with hemorrhage (46.2%). Conclusion: Neurosonogram remains the accurate, rapid imaging modality of choice for detecting brain injuries in preterm infant. This technique is both sensitive and specific for detecting germinal matrix hemorrhage and periventricular leucomalacia. It is a useful modality to perform frequent follow-up scans. The advantages of neurosonogram are that it is easy to operate, non invasive, accurate, has lack of ionizing radiation, bed side availability for unstable infants, rapid diagnosis, wide availability, cost effectiveness and repeatability.

A possible mitigation measures for urbanized residential care homes for elderly (RCHE) - acoustic window with natural ventilation

Hong Kong is well known as a densely populated city, which has an explicit usage of road traffic as its transport backbone. Severe road traffic noise problem is resulted from poorly planning in past decades, leads to the development of typical baffle type acoustic window with only one outer and one inner opening to attenuate adverse traffic noise impact. Nevertheless, extensive noise mitigation measures while allowing natural ventilation are essential when designing a RCHE. In view of the concern of the limited accessibility of the elderlies, the equal opportunity at both sides of the room to meet the needs of accessing to openable window was taken into account as far as possible. The proposed outer opening of the specially designed acoustic window is located in the middle, while the respective inner openings are located at the 2 sides. In this paper, mock-up test were carried out to analyze the acoustic performance of the specially designed acoustic window with two inner opening against the special characteristics of road traffic noise. Test results shown that the specially designed acoustic window is effective in mitigating substantial road traffic noise while providing reasonably amount of ventilation.

Guidance for fetal cardiac imaging in patients with degraded acoustic windows.

Guidance for fetal cardiac imaging in patients with degraded acoustic windows.

Role of CT in the Pre- and Postoperative Assessment of Conotruncal Anomalies.

Conotruncal anomalies, also referred to as outflow tract anomalies, are congenital heart defects that result from abnormal septation of the great vessels' outflow tracts. The major conotruncal anomalies include tetralogy of Fallot, double-outlet right ventricle, transposition of the great arteries, truncus arteriosus, and interrupted aortic arch. Other defects, which are often components of the major anomalies, include pulmonary atresia with ventricular septal defect, pulmonary valve agenesis, aortopulmonary window, and double-outlet left ventricle. CT has emerged as a robust diagnostic tool in preoperative and postoperative assessment of various congenital heart diseases, including conotruncal anomalies. The data provided with multidetector CT imaging are useful for treatment planning and follow-up monitoring after surgery or intervention. Unlike echocardiography and MRI, CT is not limited by a small acoustic window, metallic devices, and need for sedation or anesthesia. Major advances in CT equipment, including dual-source scanners, wide-detector scanners, high-efficiency detectors, higher x-ray tube power, automatic tube current modulation, and advanced three-dimensional postprocessing, provide a low-risk, high-quality alternative to diagnostic cardiac catheterization and MRI. This review explores the various conotruncal anomalies and elucidates the role of CT imaging in their pre- and postoperative assessment. Keywords: CT, CT Angiography, Stents, Pediatrics © RSNA, 2022.

A Novel Concept of a Phased-Array HIFU Transducer Optimized for MR-Guided Hepatic Ablation: Embodiment and First In-Vivo Studies.

PurposeHigh-intensity focused ultrasound (HIFU) is challenging in the liver due to the respiratory motion and risks of near-/far-field burns, particularly on the ribs. We implemented a novel design of a HIFU phased-array transducer, dedicated to transcostal hepatic thermo-ablation. Due to its large acoustic window and strong focusing, the transducer should perform safely for this application.Material and MethodsThe new HIFU transducer is composed of 256 elements distributed on 5 concentric segments of a specific radius (either 100, 111, or 125 mm). It has been optimally shaped to fit the abdominal wall. The shape and size of the acoustic elements were optimized for the largest emitting surface and the lowest symmetry. Calibration tests have been conducted on tissue-mimicking gels under 3-T magnetic resonance (MR) guidance. In-vivo MR-guided HIFU treatment was conducted in two pigs, aiming to create thermal ablation deep in the liver without significant side effects. Imaging follow-up was performed at D0 and D7. Sacrifice and post-mortem macroscopic examination occurred at D7, with the ablated tissue being fixed for pathology.ResultsThe device showed −3-dB focusing capacities in a volume of 27 × 46 × 50 mm3 as compared with the numerical simulation volume of 18 × 48 × 60 mm3. The shape of the focal area was in millimeter-range agreement with the numerical simulations. No interference was detected between the HIFU sonication and the MR acquisition. In vivo, the temperature elevation in perivascular liver parenchyma reached 28°C above physiological temperature, within one breath-hold. The lesion was visible on Gd contrast-enhanced MRI sequences and post-mortem examination. The non-perfused volume was found in pig #1 and pig #2 of 8/11, 6/8, and 7/7 mm along the LR, AP, and HF directions, respectively. No rib burns or other near-field side effects were visually observed on post-mortem gross examination. High-resolution contrast-enhanced 3D MRI indicated a minor lesion on the sternum.ConclusionThe performance of this new HIFU transducer has been demonstrated in vitro and in vivo. The transducer meets the requirement to perform thermal lesions in deep tissues, without the need for rib-sparing means.

A Transthoracic Ultrasound-Guided Needle Biopsy Provided the Diagnosis for a Synovial Sarcoma of the Pleura

A case report is presented of a 72-year-old woman with monophasic synovial sarcoma of the buttocks, diagnosed four years before. The tumor was treated with surgical removal followed by radiotherapy. The patient regularly underwent follow-up examinations and the last chest computed tomogram (CT) showed a left-sided pleural mass and ipsilateral effusion. The patient was admitted in hospital to obtain a specific histological diagnosis before treatment of chest pathology was initiated. An ultrasound (US)-guided fine needle aspiration biopsy (FNAB) of the pleural lesion and US-guided thoracentesis with drainage of blood serum pleural fluid were performed. The pathological examination of the lesion revealed a definitive diagnosis of synovial sarcoma of the pleura. For pleural-based lesions, the diagnostic accuracy of US-guided biopsy is similar to that of CT-guided biopsy, with a lower complication rate, the absence of radiation exposure to patients, and a significantly reduced procedural time. The presence of pleural effusion creates a favorable acoustic window for US-guided biopsy of pleural lesion, which is useful for the diagnosis.

P125 CORONARY REVASCULARIZATION GUIDED BY STRESS ECHOCARDIOGRAPHY WITH ULTRASOUND CONTRAST: A CASE

Abstract Echocontrastography is an echocardiography method that involves the intravenous administration of a particular contrast medium, formed by microbubbles capable of crossing the pulmonary circulation and distributing themselves in the left sections. These micro bubbles hit by ultrasound break or oscillate emitting ultrasound waves with a different frequency than the beam that hit them, generating a series of harmonic signals that can be processed to observe, for example, the opacification of the left cavities. An 82–year–old diabetic hypertensive man with a strong family history of coronary artery disease underwent routine cardiac evaluation. At the time of the visit, sporadic episodes of non–specific chest pain (localized in the right breast), of an intermittent nature, and not related to physical exertion, were reported. On the ECG, finding of sinus rhythm and q waves in V1–V3 (not present at a previous in 2019). On echocardiography (patient with poor acoustic window): Left ventricle of normal size with mild concentric parietal hypertrophy. Slight reduction in global systolic function due to alterations in district kinetics. Akinesia of the apex and middle segment of the septum and anterior wall. FE 48%. Doubtful apical iso–hyperechoicity (artifact?). Urgent hospitalization for coronary angiography was indicated in the suspicion of subacute anterior AMI. Coronary angiography revealed occlusion of anterior interventricular artery (IVA) in the proximal tract, partially re–inhabited downstream by homocoronary circulation (figure 1). Before proceeding with revascularization, given the absence of movement of the myocardiocitonecrosis indices, it was decided to perform myocardial viability tests. In consideration of the suspected apical thrombotic formation, as well as the patient‘s poor acoustic window, echo contrast was necessary (Figure 2). Once the complete opacification of the left ventricular cavity was highlighted by the contrast agent, suggestive of the absence of apex thrombi, we proceeded to ecostress with dobutamine to evaluate myocardial viability. At the explored dosages (5 – 10 and 20 ug/kg/ min) recovery of the apex kinetics was observed, but not of the mid–apical septum, which remained akinetic. We then proceeded to angioplasty on proximal IVA with a good angiographic result and the patient was discharged on the third day from revascularization in excellent clinical conditions.

P245 A RARE CAUSE OF OVERESTIMATION OF PULMONARY PRESSURE BY ECHOCARDIOGRAPHY: WHEN HEMODYNAMICS RELIEVES ECHOCARDIOGRAPHY AND ECHOCARDIOGRAPHY EXPLAINS HEMODYNAMICS

Abstract Echocardiography is the gatekeeper of the diagnostic workflow of pulmonary hypertension (PH). However, it lacks precision, and right heart catheterization (RHC) may be needed in selected cases. A morbidly obese 47–year–old woman (BMI= 58 Kg/m2) with dyspnea NYHA II was referred to our Center after a high probability of PH was found at echocardiography, this latter performed as a routine assessment before bariatric surgery. Despite a suboptimal acoustic window, the tricuspid regurgitant jet profile was well–defined, with an estimated systolic pulmonary artery pressure (PAP) of 100 mmHg. There were no overt echocardiographic signs of left heart disease. During RHC, mean PAP was just above normal values, with filling pressures at the upper limit of normal (Figure 1), high cardiac index (3.6 L/min/m2) and normal pulmonary vascular resistance (1.4 WU). The echocardiographic estimate of high systolic PAP was explained by an intraventricular RV pressure gradient of about 100 mmHg (Figure 2). Oximetry ruled out a significant intracardiac shunt. Since resting hemodynamics did not explain the patient’s symptoms, the patient pre–test probability of having heart failure with preserved ejection fraction (HFpEF) was intermediate–high, and PAWP was in a grey–zone. Accordingly, we performed an exercise RHC. The test eventually unmasked HFpEF, as witnessed by an abnormal increase of PAWP and LV end–diastolic pressure (Figure 1 panel C and D). Exercise capacity was mildly reduced (71% of predicted) due to peripheral limitation with normal cardiac and respiratory reserves. Transesophageal echocardiography was then performed. It showed a muscular obstruction below the infundibulum dividing the RV into a high–pressure apical portion and a low–pressure infundibulum (Figure 3). This rare congenital anomaly was also associated with a restrictive perimembranous ventricular septal defect. Double–chambered RV has been reported to present rarely in adults, but it might be a cause of false Doppler echocardiographic estimate of PAP. Based on a meticulous invasive hemodynamic characterization at rest and during exercise, integrated with cardiovascular imaging, we could perform such a diagnosis. This congenital anomaly did not fully explain the patient’s symptoms, which may better be attributed to cardiovascular complication of obesity (HFpEF). Accordingly, we referred the patient for bariatric surgery first, postponing the indication to cardiac surgery during the follow–up.

P121 ECHOCARDIOGRAPHIC EXAMINATION ON AGONIST ATHLETES WITH RECENT PAUCISYMPTOMATIC SARS COV 2 INFECTION, FOR THE RENEWAL OF AGONIST SPORT ACTIVITY ELIGIBILITY: PLAUSIBLE ROLE AND UTILITY OF GLS ANALYSIS THROUGH SPECKLE TRACKING

BackgroundThe aim of this work is to highlight whether or not the methodical echocardiography done through the analysis of global and segmental longitudinal deformation (GLS–SLS) can be useful to identify subclinical myocardial lesions in paucisymptomatic young agonist athletes with recent SarsCov2 infection before they return to agonist practice.Material and MethodsFrom 12/2020 to 12/2021 84 agonist athletes with previous SarsCov2 infection have been examined at “Cardiomed Center” Maglie (Lecce, IT), as part of screening for their return to sport practice; all of them under standard echocardiographic analysis associated to GLS analysis, Holter–ECG analysis with 24h on 12 derivations.ResultsThe base echocardiographic examination didn’t show any myocardial cynesis anomalies in any patient. In 5 patients there was a presence of a light pericardial effusion, how it was supposed to be as an outcome of a previous inflammatory ingjury The GLS analysis, that resulted in reliability considering the optimal acoustic window, showed a slightly lower medium value compared to the values cited in the literature (19.4 ± 2.9) and particularly 4 patients show considerable deficit reductions of segmentary strain. In these patients Holter analysis showed the presence of a moderate non–complex extrasystolic arrhythmia. These elements–that are a reduced GLS with marked regional anomaly, coupled with the presence of ventricular arrhythmia even in absence of segmentary dissinergyes– led to cardiac RMN evaluation. In 2 out of 4 patients there have been flaws that were compatible to modest myocardial lesions, in one case it was observed a marked flaw in medium–apical–lateral region that was correlated to the described areas at the specle tracking. ConclusionOur experience at the Cardiology and Sports integrated clinic, although it relied on a meager population of patients, it still demonstrated how echocardiographic analysis through GLS evaluation and the highlighting of sectorial alterations even in absence of cynesis anomalies can be used as a parameter to suppose the presence of miocarditic lesions that might be sent to the next RMN examination for confirmation, in young athletes with recent paucisymptomatic Covid–19 infection.

P108 PLEURAL EFFUSION AND THE POSTERIOR THORACIC WINDOW: ONE MORE CHANCE TO IMAGE THE AORTIC VALVE

Abstract A 85–year–old woman was admitted to our institution with acute respiratory distress. Clinical examination revealed a 5/6 systo–diastolic murmur radiating to both carotid arteries and bilateral lung crackles. Laboratory workup was notable for a N–terminal pro–brain natriuretic peptide (NT–proBNP) of 15.000 ng/L (normal range: &amp;lt; 300 ng/L) and a moderate high–sensitive troponin T elevation of 245 ng/L (normal range: &amp;lt; 14 ng/L) with no increase on serial testing. The hemoglobin and renal function was normal. Evaluation by chest X–ray showed bilateral diffuse pulmonary infiltrates consistent with pulmonary edema and bilateral pleural effusion. The patient was admitted in CCU. A transthoracic echocardiogram was performed bedside, but it was extremely difficult to obtain good quality images from standard view given the ortopnoic decubitus of the patient. However, the aortic valve was heavily calcified and severe aortic stenosis was documented with a mean gradient of 42 mmHg from apical 5 chambers view; 35 mmHg from right parasternal view, with an functional aortic valve area ≈0.6 cm2 (figure, upper panel). Left ventricle shows eccentric hypertrophy and a moderate diffuse reduction of ejection fraction (EF 35–40%). Then, the patient was positioned sitting upright, because the left pleural effusion offered an additional acoustic window—the posterior thoracic window (PTW)—that allowed better alignment of the ultrasound beam with the aortic jet. Mean gradient was recorded definitely higher than from standard view at 50 mm Hg. Moreover, aortic regurgitation that appeared mild from standard view was documented as significant from PTW. In fact, a proper alignment of the aortic regurgitation jet was feasible from this view with a quantification of severity with multiparameter criteria as suggested from the guidelines (PHT 166 ms, Vena contracta 8 mm; Rvol 60 ml). (Figure, lower panel) Conclusion Obtaining adequate echocardiographic images in critically ill patients is important for better diagnosis and treatment. For several reasons, this group of patients remains among the most challenging with regard to quality of echocardiographic images. In presence of pleural effusion and technically difficult echo exams, the PTW should be considered in the assessment of cardiac structures including aortic valve as a potentially useful option to provide further diagnostic information.

Continuous hands-free monitoring of echocardiographic exercise test using probe fixation device.

Stress echocardiography has been widely used in clinical practice for decades and has recently gained even more importance in diagnostic approaches to ischemic heart disease. However, it still has numerous limitations. Despite advantages of physical exercise as most physiologic stressor, it is impossible to continuously monitor the cardiac function during treadmill test and difficult to maintain an optimal acoustic window during cycle ergometer exercise tests. The aim herein, is to assess the feasibility of probe fixation for use during exercise echocardiography. Forty-eight subjects (47 men, mean age 42 ± 17 years, 25 healthy volunteers, 23 patients with suspected coronary artery disease) were included in this study. All subjects underwent exercise stress test on treadmill (32 cases) or cycle ergometer (16 cases). Both sector and matrix probes were used (in 17 and 31 tests, respectively). The semi-quantitative quality of acquired apical views were assessed at each stage using a four-point grading system. The mean time required for probe fixation was 9 ± 2 min. At baseline, 10 patients had at least one apical window of quality precluding reliable analysis. Twenty-five patients required probe repositioning during exercise (more often on a treadmill). During peak exercise quality of images in all views declined, but for diagnostic purposes it remained sufficient in 29 patients. Thus, 76% of performed tests (60% study population) had sufficient image quality. Probe fixation offers the possibility of continuous acquisition of echocardiographic images during physical exercise. The device is suitable almost exclusively for male patients and in some patients requires repositioning.

A New Kid on the Block in POCUS: “LISA”

A new kid on the Block in POCUS: “LISA” Transesophageal echocardiography (TTE) and computed tomography angiography (CTA) are methods of choice for definitive diagnosis and prognostic stratification of acute aortic syndromes (AAS). Point-of-care ultrasound (POCUS) has important applications in the initial workup of these patients in the emergency room (ER), ruling out other potential causes of chest pain and allowing a faster diagnosis, although conventional transthoracic echocardiographic acoustic windows do not allow for imaging of some segments of the thoracic [...]

PO-655-08 LEFT ATRIAL APPENDAGE CLOSURE USING 4D INTRACARDIAC ULTRASOUND IMAGING FROM THE CORONARY SINUS, A NOVEL APPROACH

LAAC is performed using TEE imaging in > 90% of patients in the US. There is growing experience and interest in the use of ICE imaging in place of TEE to obviate the need for general anesthesia but typically requires transeptal (TS) placement of the ICE catheter in the LA for direct LAA imaging. Novel 4D ICE catheters have the ability to image in multiple planes from a single location; however, LAA imaging from the right atrium is limited by acoustic windows. Coronary sinus (CS) imaging of the LA has been performed during ablation, and consistently provides high-quality LAA imaging, but in only a single plane with conventional ICE catheters.

Echocardiographic Assessment of Perioperative Right and Left Ventricular Function

The perioperative quantification of left and right ventricular function is cornerstone to provide optimal patient care. Echocardiography has emerged as the most important cardiac imaging modality in this setting, mainly due to its rapid availability, non-invasiveness and cost-efficiency. Both the transthoracic and the transesophageal acoustic windows offer manifold modes, e.g., doppler-based measurements or M-mode display, to assess systolic and diastolic ventricular function. An association with patient outcome and corresponding prognostic implications could be demonstrated for the majority of those parameters. Hence, a profound understanding of these measurements is key to delineate sufficient from failing left or right ventricular function and guide treatment decisions. This article gives the reader an overview over the most important measurements, reference values and pitfalls.

Parametric study of acoustic windows using a Green’s Function transfer matrix method

The Green’s function dependent transfer matrix method was applied to model sound transmission loss of a plenum window with a given configuration. The analytically calculated transmission loss reasonably followed that of the experimental data obtained from a previous study. The troughs in the calculated transmission loss spectra were found aligning well with the natural frequencies of the acoustic modes inside the plenum chamber. Vectorization of the calculations shows a 10-fold acceleration in computation, enabling desktop evaluation of transmission losses of plenum window systems with various configurations. Utilizing the analytical model, a parametric study of varying the three crucial design parameters, including the gap width, the overlapping length and the area ratio, between the outlet and inlet openings of the plenum window was conducted. The results demonstrated that increases in the latter two design parameters would improve the transmission loss performance of the plenum window at low frequencies, while increasing the gap width would compromise its transmission loss performance. Also, an increase in the overlapping length would widen the frequency range coverage with elevated transmission loss performance.

Design and validation of a phantom for transcranial ultrasonography.

Commercial medical ultrasound phantoms are highly specific as they simulate particular clinical scenarios. This makes them expensive to use in multi-target research and training. General approaches to human tissue and organ modeling are described in the manufacturing methodology, access to which is restricted by the manufacturer's trade secret. Our aim is to propose a reproducible methodology to design a head phantom for transcranial ultrasound training and research from widely available materials and to validate its applicability. To create an anthropomorphic phantom, we used data from real patients obtained by CT and MRI scans. We combined FDM and LCD 3D printing to achieve the desired acoustic performance and ergonomics of the phantom. We fabricated the phantom using polyvinyl chloride plastisol, photopolymer, and PLA to simulate brain tissue, temporal acoustic windows, and acoustically opaque parts of the skull, respectively. Notably, the phantom fabrication method uses only readily available materials and is easy to reproduce. We developed a basic one and anatomical one versions of the head phantom. The basic version contains a simplified brain: tissue-mimicking material is poured into the skull with needles inserted, which specific pattern is easy to recognize in B-mode images. The anatomical version has an anatomically correct brain dummy extracted from MRI data and contains multiple randomly distributed small metal, plastic, and bony objects ranging in size from 1 to 3mm each. The proposed methodology allows producing head phantoms for transcranial ultrasound training and research. The anatomical accuracy of the model is proved by ultrasonography and CT studies. Both versions of the phantom comprise the skull and the brain and are intended for ultrasound imaging through the temporal bone acoustic window. Needles and small objects serve as navigation targets during the training procedure. The basic version helps learning basic navigation skills, while the anatomical one provides a realistic setting to perform the diagnostic procedure.

Characterizing the biomechanical differences between novice and expert point-of-care ultrasound practitioners using a low-cost gyroscope and accelerometer integrated sensor: A pilot study.

Point-of-care ultrasound (POCUS) has become an important diagnostic tool in acute care medicine; however, little is known about the biomechanical differences between novice and expert practitioners. A low-cost ($50 CAD) gyroscope and accelerometer integrated sensor was assembled and affixed to an ultrasound probe. Seventeen participants, nine novices and eight experts, were recruited to perform three abdominal and four cardiac scans on a standardized patient. Participant demographics, time per scan, average acceleration, average angular velocity, decay in acceleration and angular velocity over time, and frequency of probe movements were analyzed. Video capture with blinded video review was scored. On video review, experts had higher image optimization and acquisition scores for both abdominal and cardiac scans. Experts had shorter scan times for abdominal (7s vs. 26s, p=0.003) and cardiac (11s vs. 26s, p<0.001) scans. There was no difference in average acceleration (g) between novices and experts performing abdominal (1.02 vs. 1.01, p=0.50) and cardiac (1.01 vs. 1.01, p=0.45) scans. Experts had lower angular velocity (°/s) for abdominal scans (10.00 vs. 18.73, p<0.001) and cardiac scans (15.61 vs. 20.33, p=0.02) There was a greater decay in acceleration over time for experts performing cardiac scans compared to novices (-0.194 vs. -0.050, p=0.03) but not for abdominal scans or when measuring angular velocity. The frequency of movements (Hz) was higher for novices compared to experts for abdominal (16.68 vs. 13.79, p<0.001) and cardiac (17.60 vs. 13.63, p=0.002) scans. This study supports the feasibility of a low-cost gyroscope and accelerometer integrated sensor to quantify the biomechanics of POCUS. It may also support the concept of "window shopping" as a method by which experts obtain abdominal and cardiac views, where sliding is used to find an acoustic window, then smaller rocking and tilting probe movements are used to refine the image.