Best Practice Recommendations for the Safe use of Lung Ultrasound.

The safety of ultrasound is of particular importance when examining the lungs, due to specific bioeffects occurring at the alveolar air-tissue interface. Lung is significantly more sensitive than solid tissue to mechanical stress. The causal biological effects due to the total reflection of sound waves have also not been investigated comprehensively.On the other hand, the clinical benefit of lung ultrasound is outstanding. It has gained considerable importance during the pandemic, showing comparable diagnostic value with other radiological imaging modalities.Therefore, based on currently available literature, this work aims to determine possible effects caused by ultrasound on the lung parenchyma and evaluate existing recommendations for acoustic output power limits when performing lung sonography.This work recommends a stepwise approach to obtain clinically relevant images while ensuring lung ultrasound safety. A special focus was set on the safety of new ultrasound modalities, which had not yet been introduced at the time of previous recommendations.Finally, necessary research and training steps are recommended in order to close knowledge gaps in the field of lung ultrasound safety in the future.These recommendations for practice were prepared by ECMUS, the safety committee of the EFSUMB, with participation of international experts in the field of lung sonography and ultrasound bioeffects.

Professional Standards in Medical Ultrasound - EFSUMB Position Paper (Long Version) - General Aspects.

This first position paper of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) on professional standards presents a common position across the different medical professions within EFSUMB regarding optimal standards for the performing and reporting of ultrasound examinations by any professional ultrasound operator. It describes general aspects of professionality that ensure procedure quality, effectiveness, efficiency, and sustainability in virtually all application fields of medical ultrasound. Recommendations are given related to safety and indication of ultrasound examinations, requirements for examination rooms, structured examination, systematic reporting of results, and management, communication and archiving of ultrasound data. The print version of this article is a short version. The long version is published online.

Professional Standards in Medical Ultrasound - EFSUMB Position Paper (Short Version) - General Aspects.

This first position paper of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) on professional standards presents a common position across the different medical professions within EFSUMB regarding optimal standards for the performing and reporting of ultrasound examinations by any professional ultrasound operator. It describes general aspects of professionality that ensure procedure quality, effectiveness, efficiency, and sustainability in virtually all application fields of medical ultrasound. Recommendations are given related to safety and indication of ultrasound examinations, requirements for examination rooms, structured examination, systematic reporting of results, and management, communication and archiving of ultrasound data. The print version of this article is a short version. The long version is published online.

Safety Aspects of Perinatal Ultrasound.

Ultrasound safety is of particular importance in fetal and neonatal scanning. Fetal tissues are vulnerable and often still developing, the scanning depth may be low, and potential biological effects have been insufficiently investigated. On the other hand, the clinical benefit may be considerable. The perinatal period is probably less vulnerable than the first and second trimesters of pregnancy, and ultrasound is often a safer alternative to other diagnostic imaging modalities. Here we present step-by-step procedures for obtaining clinically relevant images while maintaining ultrasound safety. We briefly discuss the current status of the field of ultrasound safety, with special attention to the safety of novel modalities, safety considerations when ultrasound is employed for research and education, and ultrasound of particularly vulnerable tissues, such as the neonatal lung. This CME is prepared by ECMUS, the safety committee of EFSUMB, with contributions from OB/GYN clinicians with a special interest in ultrasound safety.

EFSUMB Clinical Safety Statement for Diagnostic Ultrasound - (2019 revision).

This document is the updated 2019 revision of the EFSUMB Clinically Safety Statement. A Safety Statement has been published by EFSUMB annually since 1994 by the Safety Committee (ECMUS) of the federation. The text is deliberately brief and gives a concise overview of safety in the use of diagnostic ultrasound.

The EFSUMB Guidelines and Recommendations for the Clinical Practice of Elastography in Non-Hepatic Applications: Update 2018.

This manuscript describes the use of ultrasound elastography, with the exception of liver applications, and represents an update of the 2013 EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) Guidelines and Recommendations on the clinical use of elastography.

The effect of dead elements on the accuracy of Doppler ultrasound measurements.

The objective of this study is to investigate the effect of multiple dead elements in an ultrasound probe on the accuracy of Doppler ultrasound measurements. For this work, we used a specially designed ultrasound imaging system, the Ultrasonix Sonix RP, that provides the user with the ability to disable selected elements in the probe. Using fully functional convex, linear, and phased array probes, we established a performance baseline by measuring the parameters of a laminar parabolic flow profile. These same parameters were then measured using probes with 1 to 10 disabled elements. The acquired velocity spectra from the functional probes and the probes with disabled elements were then analyzed to determine the overall Doppler power, maximum flow velocity, and average flow velocity. Color Flow Doppler images were also evaluated in a similar manner. The analysis of the Doppler spectra indicates that the overall Doppler power as well as the detected maximum and average velocities decrease with the increasing number of disabled elements. With multiple disabled elements, decreases in the detected maximum and average velocities greater than 20% were recorded. Similar results were also observed with Color Flow Doppler measurements. Our results confirmed that the degradation of the ultrasound probe through the loss of viable elements will negatively affect the quality of the Doppler-derived diagnostic information. We conclude that the results of Doppler measurements cannot be considered accurate or reliable if there are four or more contiguous dead elements in any given probe.

A prototype of a handheld augmented reality application to get familiar with ultrasound equipment knobology.

AIMS: A prototype application has been developed that is adapting modern augmented reality technology to support learning in ultrasound skills-labs or at home. The application enables students to get in real-time an orientation and information about the knobs on an equipment´s control panel that is available in the lab. MATERIAL AND METHODS: The Augmented reality (AR) application for smartphones or tablets was created in Unity (San Francisco) with the software development kit Vuforia (Vuforia PTC Inc., Zurich) to support students with their own devices to learn the knobology of an ultrasound equipment. An interface was modelled, which is superimposed on the live camera image and provides information about the displayed knobs and sliders on the control panel. RESULTS: The smartphone or tablet app is able to detect the specific ultrasound equipment in real in the skills-lab, as well as from a hardcopy photo or displayed by a monitor and to provide further detailed information. The application can be used therefore as preparation of a practical course or for orientation within the lab at the equipment. CONCLUSIONS: The flexibility of the app is optimal for students to become familiar with the equipment before they are having their skills-lab lecture and might help to reduce time for introduction to orientation at the equipment´s console.

Developing and using a smartphone-app to support the teaching of technical basics for 3D/4D obstetrical ultrasound applications in medical education.

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[Teaching Technical Basics in Ultrasound for Medical Students - Outline of the Viennese 'Teach Us Sound' Concept]. / Vermittlung technischer Grundlagen bei der studentischen Ultraschallausbildung ­ das Wiener «Teach US Sound¼-Konzept im Überblick.

Teaching Technical Basics in Ultrasound for Medical Students - Outline of the Viennese 'Teach Us Sound' Concept Abstract. Teaching technical ultrasound basics in regular medical curricula is possible to small extent only and not adequate. This contribution will give a survey of the lectures focussed on "ultrasound" at the Medical University of Vienna and presents a concept how to impart basic technical competences in practice. The contents of the concept and some detail aspects of it will be presented and the benefit for students discussed.

New sonographic techniques for harmonic imaging--underlying physical principles.

In this paper, modern harmonic imaging techniques are reviewed and their physical principles are explained. The clinical advantages of these new techniques that are generally used in conjunction with ultrasound contrast agents are highlighted and compared to conventional flow imaging methods. Low/high mechanical index (MI) methods are discussed as well as emerging technologies for future transducer or beamformer generations. Finally the latest safety issues concerning applications of modern (harmonic) imaging techniques with contrast agents are given.

Effects of Pulsed Ultrasound Therapy on Sensory Nerve Conduction Parameters and the Pain Threshold Perceptions in Humans.

BACKGROUND: Therapeutic ultrasound is an often-used clinical modality in the nonsurgical treatment of entrapment neuropathies. To date, the possible mechanism of action of pulsed ultrasound therapy on the peripheral nerve in the treatment of entrapment neuropathies is unclear. OBJECTIVE: To examine the effects of pulsed ultrasound therapy on peripheral nerve conduction parameters. DESIGN: A prospective, randomized, single blind, crossover study. SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation. PARTICIPANTS: Twelve healthy volunteers between 22 and 38 years of age (8 male, 4 female). METHODS: Each patient (blinded) received ultrasound therapy (1W/cm2, pulsed: 1:5; over the course of the superficial branch of the radial nerve of the nondominant arm) and placebo (intensity: zero). The interval between the individual interventions was 1 week. MAIN OUTCOME MEASUREMENT: The sensory nerve conduction velocity, sensory nerve action potential, supramaximal stimulation intensity of the sensory fibers of the radial nerve, and the pressure pain threshold in the sensory area of the radial nerve before and after an ultrasound-therapy and placebo intervention. To compare the results of the intervention with placebo, a paired-samples t test was applied. RESULTS: Compared with placebo, a significant increase after pulsed ultrasound therapy was found for the supramaximal stimulation intensity (P = .02). For the other primary outcome parameters, a significant difference was not found. CONCLUSIONS: The immediate effect of pulsed ultrasound therapy on a sensory nerve is minimal. Therefore, the previously reported benefit of pulsed ultrasound therapy in entrapment neuropathies might be not due to its effect on the sensory nerve. LEVEL OF EVIDENCE: I.

All-optical highly sensitive akinetic sensor for ultrasound detection and photoacoustic imaging.

A novel all-optical akinetic ultrasound sensor, consisting of a rigid, fiber-coupled Fabry-Pérot etalon with a transparent central opening is presented. The sensing principle relies exclusively on the detection of pressure-induced changes of the refractive index in the fluid filling the Fabry-Pérot cavity. This enables resonance-free, inherently linear signal detection over a broad bandwidth. We demonstrate that the sensor achieves a exceptionally low peak noise equivalent pressure (NEP) values of 2 Pa over a 20 MHz measurement bandwidth (without signal averaging), while maintaining a flat frequency response, and a detection bandwidth up to 22.5 MHz (-6 dB). The measured large full field of view of the sensor is 2.7 mm × 1.3 mm and the dynamic range is [Formula: see text] or 63 dB at 20 MHz bandwidth. For different required amplitude ranges the upper amplitude detection limit can be customized from at least 2 kPa to 2 MPa by using cavity mirrors with a lower optical reflectivity. Imaging tests on a resolution target and on biological tissue show the excellent suitability of the akinetic sensor for optical resolution photoacoustic microscopy (OR-PAM) applications.

Can a commercial diagnostic ultrasound device accelerate thrombolysis? An in vitro skull model.

BACKGROUND AND PURPOSE: Recently, 3 clinical trials revealed encouraging results in recanalization and clinical outcome in acute stroke patients when 2-MHz transcranial Doppler monitoring was applied. This study investigated whether a 1.8-MHz commercial diagnostic ultrasound device has the potential to facilitate thrombolysis using an in vitro stroke model. METHODS: Duplex-Doppler, continuous wave-Doppler, and pulsed wave (PW)-Doppler were compared on their impact on recombinant tissue plasminogen activator (rtPA)-mediated thrombolysis. Blood clots were transtemporally sonicated in a human stroke model. Furthermore, ultrasound attenuation of 5 temporal bones of different thickness was determined. RESULTS: In comparison, only PW-Doppler accelerated rtPA-mediated thrombolysis significantly. Without temporal bone, PW-Doppler plus rtPA showed a significant enhancement in relative clot weight loss of 23.7% when compared with clots treated with rtPA only (33.9+/-5.5% versus 27.4+/-5.2%; P<0.0005). Ultrasound attenuation measurements revealed decreases of the output intensity of 86.8% (8.8 dB) up to 99.2% (21.2 dB), depending on temporal bone thickness (1.91 to 5.01 mm). CONCLUSIONS: Without temporal bone, PW-Doppler significantly enhanced thrombolysis. However, because of a high attenuation of ultrasound by temporal bone, no thrombolytic effect was observed in our in vitro model, although Doppler imaging through the same temporal bone was still possible.

Excitability of chronic hemiparetic muscles: determination of chronaxie values and strength-duration curves and its implication in functional electrical stimulation.

Central nervous system disorders affect the anatomy and physiology of the lower motoneuron. This fact has an impact on the stimulation parameters, especially on the duration of the stimulating impulses, for functional electrical stimulation in chronic hemiparetic patients. The aim of this study was thus to test the excitability and to determine chronaxie values and strength-duration curves of weak wrist and finger extensor muscles and spastic finger and wrist flexor muscles in the hemiparetic arm. Twelve patients with chronic hemiplegia (>6 months after the onset of the cerebral lesion) participated in the study. A constant current stimulator was used. As to chronaxie values no significant differences were found between the extensor muscles (mean+/-SD: 0.44+/-0.16 ms) and flexor muscles (mean+/-SD: 0.36+/-0.22 ms). A moderate variability was seen for both extensor muscles (0.2-0.8 ms) and flexor muscles (0.1-0.9 ms). These values are well within the normal range determined for innervated muscles. All strength-duration curves were completely normal for each muscle. We conclude that in chronic hemiparetic muscles, impulses of the same duration can be used as in muscles of healthy subjects.

Measurement of Thermal Effects of Doppler Ultrasound: An In Vitro Study.

OBJECTIVE: Ultrasound is considered a safe imaging modality and is routinely applied during early pregnancy. However, reservations are expressed concerning the application of Doppler ultrasound in early pregnancy due to energy emission of the ultrasound probe and its conversion to heat. The objective of this study was to evaluate the thermal effects of emitted Doppler ultrasound of different ultrasound machines and probes by means of temperature increase of in-vitro test-media. METHODS: We investigated the energy-output of 5 vaginal and abdominal probes of 3 ultrasound machines (GE Healthcare, Siemens, Aloka). Two in-vitro test objects were developed at the Center for Medical Physics and Biomedical Engineering, Medical University Vienna (water bath and hydrogel bath). Temperature increase during Doppler ultrasound emission was measured via thermal sensors, which were placed inside the test objects or on the probes' surface. Each probe was emitting for 5 minutes into the absorbing test object with 3 different TI/MI settings in Spectral Doppler mode. RESULTS: During water bath test, temperature increase varied between 0.1 and 1.0°C, depending on probe, setting and focus, and was found highest for spectral Doppler mode alone. Maximum temperature increase was found during the surface heating test, where values up to 2.4°C could be measured within 5 minutes of emission. CONCLUSIONS: Activation of Doppler ultrasound in the waterbath model causes a significant increase of temperature within one minute. Thermally induced effects on the embryo cannot be excluded when using Doppler ultrasound in early pregnancy.

Evaluation of a miniature electromagnetic position tracker.

The advent of miniaturized electromagnetic digitizers opens a variety of potential clinical applications for computer aided interventions using flexible instruments; endoscopes or catheters can easily be tracked within the body. With respect to the new applications, the systematic distortions induced by various materials such as closed metallic loops, wire guides, catheters, and ultrasound scan heads were systematically evaluated in this paper for a new commercial tracking system. We employed the electromagnetic tracking system Aurora (Mednetix/CH, NDI/Can); data were acquired using the serial port of a PC running SuSE Linux 7.1 (SuSE, Gmbh, Nürnberg). Objects introduced into the digitizer volume included wire loops of different diameters, wire guides, optical tracking tools, an ultrasonic (US) scan head, an endoscope with radial ultrasound scan head and various other objects used in operating rooms and interventional suites. Beyond this, we determined the influence of a C-arm fluoroscopy unit. To quantify the reliability of the system, the miniaturized sensor was mounted on a nonmetallic measurement rack while the transmitter was fixed at three different distances within the digitizer range. The tracker was shown to be more sensitive to distortions caused by materials close to the emitter (average distortion error 13.6 mm +/- 16.6 mm for wire loops positioned at a distance between 100 mm and 200 mm from the emitter). Distortions caused by materials near the sensor (distances smaller than 100 mm) are small (typical error 2.2 mm +/- 1.9 mm). The C-arm fluoroscopy unit caused considerable distortions and limits the reliability of the tracker (distortion error 18.6 mm +/- 24.9 mm). Distortions resulting from the US scan head are high at distances smaller than about 100 mm from the emitter. The distortions also increase when the scan head is positioned horizontally and close to the sensor (average error 4.1 mm +/- 1.5 mm when the scan head is positioned within a distance of 100 mm from the sensor). The distortions are slightly higher when the ultrasound machine is switched on. We also evaluated the influence of common medical instruments on distance measurements. For these measurements the average deviation from the known distance of 200 mm amounted to 3.0 mm +/- 1.5 mm (undistorted distance measurement 1.5 mm +/- 0.3 mm). The deviations also depend on the relative orientation between emitter and sensor. The results demonstrate that the miniature tracking system opens up new perspectives with regard to surgery applications where a flexible instrument is to be tracked within the body. Significant distortions caused by metallic objects only occur in the worst cases, for example, in the presence of a closed, unisiolated wire loop or a C-arm fluorescence unit close to the emitter and which can be avoided by suitable usage.

In vitro thrombolysis enhanced by standing and travelling ultrasound wave fields.

Success of thrombolytic therapy depends on penetration of recombinant tissue plasminogen activator (rt-PA) into clots. Ultrasound (US) of therapeutic quality accelerates thrombolysis in vitro. As yet, only the effects of travelling acoustic waves on thrombolysis have been investigated, and the impact of standing acoustic waves has been neglected. In the present study, we examined the effects of standing and travelling US wave fields applied continuously for 1 h (frequency 2 MHz, acoustic intensity 1.2 W/cm(2)) on thrombolysis enhancement by measuring clot weight reduction and concentration of fibrin degradation product D-dimer (FDP-DD) produced from clots subjected to rt-PA. The level of FDP-DD was 1.8 times greater in travelling than in standing acoustic waves. Thrombolysis enhancement was 46.0 +/- 20.8% in standing and 116.8 +/- 23.1% in travelling acoustic waves. Travelling waves enhanced thrombolysis significantly more (p < 0.0001) than did standing waves.

Variations in the output power and surface heating effects of transducers in therapeutic ultrasound.

OBJECTIVE: To determine the real emitted output power and maximum surface heating of commercial therapeutic ultrasound transducers emitting in air for various therapeutic regimens. DESIGN: Surface temperatures of ultrasound transducers with frequencies of .05 to 3 MHz were detected over 5 minutes by using a calibrated infrared thermographic camera; additionally, the indicated output power was checked with a radiation force balance. SETTING: University center for biomedical engineering and physics and medical school for physical medicine and rehabilitation. PARTICIPANTS: Not applicable. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Power variations and surface temperatures of clinical devices were analyzed to determine whether they comply with obligatory limits given in International Electrotechnical Commission standard 60601-2-5. RESULTS: Depending on the operation mode and the output power, surface temperatures ranged between 24.2 degrees to 80 degrees C within 5 minutes. Differences between measured and displayed power output (limit, +/-20%) ranged between -32% and 28%. CONCLUSIONS: The effectiveness of treatment is lowered if the value of emitted power is not known reliably. In the worst case, damage or irritation of the skin is possible, particularly in patients with sensory compromised skin. Damage may be caused by hot surfaces if the threshold level required to activate the device is lowered or if the device is defective. Improved thermal control units are necessary to prevent potential thermal hazards. Regular checks of transducer emission should be obligatory to ensure correct and precise function of the clinical devices.