IMU-Assisted Manual 3D-Ultrasound Imaging Using Motion-Constrained Swept-Fan Scans.

Three-dimensional (3D) ultrasonic imaging can enable post-facto plane of interest selection. It can be performed with devices such as wobbler probes, matrix probes, and sensor-based probes. Ultrasound systems that support 3D-imaging are expensive with added hardware complexity compared to 2D-imaging systems. An inertial measurement unit (IMU) can potentially be used for 3D-imaging by using it to track the motion of a one-dimensional array probe and constraining its motion in one degree of freedom (1-DoF) rotation (swept-fan). This work demonstrates the feasibility of an affordable IMU-assisted manual 3D-ultrasound scanner (IAM3US). A consumer-grade IMU-assisted 3D scanner prototype is designed with two support structures for swept-fan. After proper IMU calibration, an appropriate KF-based algorithm estimates the probe orientation during the swept-fan. An improved scanline-based reconstruction method is used for volume reconstruction. The evaluation of the IAM3US system is done by imaging a tennis ball filled with water and the head region of a fetal phantom. From fetal phantom reconstructed volumes, suitable 2D planes are extracted for biparietal diameter (BPD) manual measurements. Later, in-vivo data is collected. The novel contributions of this paper are (1) the application of a recently proposed algorithm for orientation estimation of swept-fan for 3D imaging, chosen based on the noise characteristics of selected consumer grade IMU (2) assessment of the quality of the 1-DoF swept-fan scan with a deflection detector along with monitoring of maximum angular rate during the scan and (3) two probe holder designs to aid the operator in performing the 1-DoF rotational motion and (4) end-to-end 3D-imaging system-integration. Phantom studies and preliminary in-vivo obstetric scans performed on two patients illustrate the usability of the system for diagnosis purposes.

Suboptimal accuracy of ultrasound and ultrasound-based risk stratification systems in detecting medullary thyroid carcinoma should not be overlooked. Findings from a systematic review with meta-analysis.

OBJECTIVE: Ultrasound (US) is the pivotal procedure during the diagnostic work-up of thyroid nodule and several US-based risk stratification systems (RSSs) have been recently developed. Since the performance of RSSs in detecting medullary thyroid carcinoma (MTC) has been rarely investigated, the present systematic review aimed to achieve high evidence about (1) how MTC is classified according to RSSs; (2) if RSSs correctly classify MTC at high risk/suspicion, and (3) if MTC is classified as suspicious at US when RSSs are not used. DESIGN: The review was performed according to MOOSE. The online search was performed by specific algorithm on January 2022. A random-effects model was used for statistical analysis. RESULTS: Twenty-five papers were initially included and their risk of bias was generally low. According to ATA system, 65% of MTCs was assessed at high suspicion and 25% at intermediate suspicion. Considering all RSSs, a 54.8% of MTCs was put in a high-risk/suspicion category. Pooling data from studies without data of RSS the prevalence of ultrasonographically suspicious MTCs was 60%. CONCLUSIONS: As conclusion, MTC presentation according to RSSs is partially known and it is classified in a high-risk/suspicion category of RSSs in just over a half of cases. This advises for further studies, ideally supported by international societies, to better define the US presentation of MTC.

An Experimental Ultrasound System for Qualitative Tomographic Imaging.

The advancement of new promising techniques in the field of biomedical imaging has always been paramount for the research community. Recently, ultrasound tomography has proved to be a good candidate for non-invasive and safe diagnostics. In particular, breast cancer imaging may benefit from this approach, as frequent screening and early diagnosis require decreased system size and costs compared to conventional imaging techniques. Furthermore, a major advantage of these approaches consists in the operator-independent feature, which is very desirable compared to conventional hand-held ultrasound imaging. In this framework, the authors present some imaging results on an experimental campaign acquired via an in-house ultrasound tomographic system designed and built at the University of Naples Parthenope. Imaging performance was evaluated via different tests, showing good potentiality in structural information retrieval. This study represents a first proof of concept in order to validate the system and to consider further realistic cases in near future applications.

Handheld transabdominal ultrasound, after limited training, may confirm first trimester viable intrauterine pregnancy: a prospective cohort study.

OBJECTIVES: Handheld point-of-care abdominal ultrasound (POCUS) may be used by primary care physicians while vaginal ultrasound is limited to use in specialist care. We aimed to compare abdominal handheld ultrasound to vaginal ultrasound in determining first trimester viable intrauterine pregnancy and estimate gestational length. DESIGN: Prospective cohort study. SETTING: Gynaecologic outpatient clinic; women referred from GPs during early pregnancy. Handheld ultrasound using VscanExtend® was performed by fourth-year medical students with limited training. Transvaginal ultrasound using high-end devices was performed by ordinary hospital staff. SUBJECTS: Women in the first trimester of pregnancy referred for termination of pregnancy or with symptoms of early pregnancy complications. MAIN OUTCOME MEASURES: Rate of confirming vital intrauterine pregnancy (visualizing foetal heart beats) and measurement of crown-rump length (CRL) using handheld abdominal versus vaginal ultrasound. RESULTS: In all 100 women were included; 86 confirmed as viable intrauterine pregnancies and 14 pathological pregnancies (miscarriages/extrauterine pregnancies). Handheld abdominal ultrasound detected fetal heartbeats in 63/86 (73% sensitivity) of healthy pregnancies and confirmed lack of fetal heartbeats in all pathological pregnancies, total positive predictive value (PPV) 100% and total negative predictive value (NPV) 38%. From gestational week 7, handheld abdominal ultrasound confirmed vitality in 51/54 patients: PPV 100% and NPV 79%. CRL (n = 62) was median 1 mm shorter (95% confidence interval 1-2 mm) measured by handheld abdominal versus vaginal ultrasound. CONCLUSION: Handheld ultrasound has an excellent prediction confirming viable intrauterine pregnancy from gestational week 7. Validation studies are needed to confirm whether the method is suitable in primary care assessing early pregnancy complications.KEY POINTSWhen early pregnancy vitality needs to be confirmed, women will traditionally be referred to secondary care for transvaginal comprehensive ultrasonography performed with high-end devices by imaging specialists.In this study personnel with limited former training (fourth-year medical students) performed transabdominal POCUS using a handheld device, investigating 100 first trimester pregnancies for confirmation of viability.Using handheld ultrasound viable pregnancy was confirmed from gestational week 7 with 79% positive and 100% negative predictive value.If handheld ultrasound used in primary care confirms vital intrauterine pregnancy, the need for specialist referral could be reduced.

Prelinearized Class-B Power Amplifier for Piezoelectric Transducers and Portable Ultrasound Systems.

Portable ultrasound systems typically suffer from unwanted heat and limited battery life, resulting in reduced system performance or the applicable number of piezoelectric transducer elements. This can be a bottleneck in widely used portable ultrasound systems. Class-A power amplifiers are typically used in portable ultrasound systems. However, unwanted heat dissipation needs to be reduced by using large cooling fans and heat pipe structures. To reduce unwanted heat, class-B power amplifiers may be a possible solution. However, the non-linearity of class-B power amplifiers could limit their integration with piezoelectric transducers because non-linearity in the high-voltage output of the power amplifiers deteriorates the sensitivity of portable ultrasound systems. To improve the linearity of the power amplifier, we developed prelinearized class-B power amplifiers for piezoelectric transducers and portable ultrasound systems. To verify our proposed method, we compared the performances of class-B and prelinearized class-B power amplifiers in their pulse-echo responses. Therefore, prelinearized class-B power amplifiers are a possible solution to produce better echo signal performance in piezoelectric transducers and portable ultrasound systems.

Development of a Class-C Power Amplifier with Diode Expander Architecture for Point-of-Care Ultrasound Systems.

Point-of-care ultrasound systems are widely used in ambulances and emergency rooms. However, the excessive heat generated from ultrasound transmitters has an impact on the implementation of piezoelectric transducer elements and on battery consumption, thereby affecting the system's sensitivity and resolution. Non-linear power amplifiers, such as class-C amplifiers, could substitute linear power amplifiers, such as class-A amplifiers, which are currently used in point-of-care ultrasound systems. However, class-C power amplifiers generate less output power, resulting in a reduction of system sensitivity. To overcome this issue, we propose a new diode expander architecture dedicated to power amplifiers to reduce the effects of sinusoidal pulses toward the power supply. Thus, the proposed architecture could increase the input pulse amplitudes applied to the main transistors in the power amplifiers, hence increasing the output voltage of such amplifiers. To verify the proposed concept, pulse-echo responses from an ultrasonic transducer were tested with the developed class-C power amplifier using a resistor divider and the designed diode expander architecture. The peak-to-peak amplitude of the echo signals of the ultrasonic transducers when using a class-C power amplifier with a diode expander architecture (2.98 Vp-p) was higher than that for the class-C power amplifier with a resistor divider architecture (2.51 Vp-p). Therefore, the proposed class-C power amplifier with diode expander architecture is a potential candidate for improving the sensitivity performance of piezoelectric transducers for point-of-care ultrasound systems.

Ultrasound images transmitted via FaceTime are non-inferior to images on the ultrasound machine.

PURPOSE: Remote telementored ultrasound (RTMUS) systems can deliver ultrasound (US) expertise to regions lacking highly trained bedside ultrasonographers and US interpreters. To date, no studies have evaluated the quality and clinical utility of US images transmitted using commercially available RTMUS systems. METHODS: This prospective pilot evaluated the quality of US images (right internal jugular vein, lung apices and bases, cardiac subxiphoid view, bladder) obtained using a commercially available iPad operating FaceTime software. A bedside non-physician obtained images and a tele-intensivist interpreted them. All US screen images were simultaneously saved on the US machine and captured via a FaceTime screen shot. The tele-intensivist and an independent US expert rated image quality and utility in guiding clinical decisions. RESULTS: The tele-intensivist rated FaceTime images as high quality (90% [69/77]) and could comfortably make clinical decisions using these images (96% [74/77]). Image quality did not differ between FaceTime and US images (97% (75/77). Strong inter-rater reliability existed between tele-intensivist and US expert evaluations (Spearman's rho 0.43; P<.001). CONCLUSION: An RTMUS system using commercially available two-way audiovisual technology can transmit US images without quality degradation. For most anatomic sites assessed, US images acquired using FaceTime are not inferior to those obtained directly with the US machine.

Tele-intensivists can instruct non-physicians to acquire high-quality ultrasound images.

PURPOSE: Intensive care unit telemedicine (tele-ICU) uses audiovisual systems to remotely monitor and manage patients. Intensive care unit ultrasound can augment an otherwise limited bedside evaluation. To date, no studies have utilized tele-ICU technology to assess the quality and clinical use of real-time ultrasound images. We assessed whether tele-intensivists can instruct nonphysicians to obtain high-quality, clinically useful ultrasound images. METHODS: This prospective pilot evaluated the effectiveness of a brief educational session of nonphysician "ultrasonographers" on their ability to obtain ultrasound images (right internal jugular vein, bilateral lung apices and bases, cardiac subxiphoid view, bladder) with real-time tele-intensivist guidance. All ultrasound screen images were simultaneously photographed with a 2-way camera and saved on the ultrasound machine. The tele-intensivist assessed image quality, and an independent ultrasound expert rated their use in guiding clinical decisions. RESULTS: The intensivist rated the tele-ICU camera images as high quality (70/77, 91%) and suitable for guiding clinical decisions (74/77, 96%). Only bilateral lung apices demonstrated differences in quality and clinical use. All other images were rated noninferior and clinically useful. CONCLUSION: Tele-intensivists can guide minimally trained nonphysicians to obtain high-quality, clinically useful ultrasound images. For most anatomic sites, tele-ICU images are of similar quality to those acquired directly by ultrasound.