[Technical innovations to optimize ultrasound imaging]

Due to the high incidence of thyroid disease, ultrasound examination of the neck has high priority in many nuclear medicine departments. A precise sonogram with high spatial resolution and image sharpness over the entire imaging area, combined with minimal artifacts, is the prerequisite for meeting the demand for high diagnostic accuracy in modern medicine. In the last 20-30 years, a number of significant technical innovations have been implemented, such as the development of the matrix array, electronic image focusing, realtime compound imaging, artifact limitation by speckle reduction and harmonic imaging, as well as the possibility to extend the field of view.

Best Practice Guideline - DEGUM Recommendations on Breast Ultrasound

Alongside mammography, breast ultrasound is an important and well-established method in assessment of breast lesions. With the "Best Practice Guideline", the DEGUM Breast Ultrasound (in German, "Mammasonografie") working group, intends to describe the additional and optional application modalities for the diagnostic confirmation of breast findings and to express DEGUM recommendations in this Part II, in addition to the current dignity criteria and assessment categories published in Part I, in order to facilitate the differential diagnosis of ambiguous lesions.The present "Best Practice Guideline" has set itself the goal of meeting the requirements for quality assurance and ensuring quality-controlled performance of breast ultrasound. The most important aspects of quality assurance are explained in this Part II of the Best Practice Guideline.

[Perspectives and Challenges of hand-held Ultrasound]

The use of handheld ultrasound devices from a technical and data protection point of view, device properties, functionality, documentation, indications, delegation of performance, applications by doctors, students and non-medical staff is examined and discussed.

How safe is it to use ultrasound in prenatal medicine? Facts and contradictions - Part 2 - Laboratory experiments regarding non-thermal effects and epidemiological studies

The first part of this CME article (issue 5/20) provided a detailed examination of the biophysical effects of ultrasound waves, the exposure values, and in particular the thermal effect. In vivo and in vitro measurements have shown that the temperature increase in tissue associated with B-mode ultrasound is far too low to pose a potential risk. Even experiments with exposure values in the range of pulsed Doppler have shown that temperature increases of over 1.5 °C can only occur in areas in direct contact with the probe, thus making a limited exposure time particularly in the case of transvaginal application advisable. The second part of this CME article describes various laboratory and animal experiments for evaluating non-thermal effects and also presents the most important epidemiological studies in the last 30 years in the form of an overview and review. In addition to direct insonation of isolated cells to examine possible mutagenic effects, the blood of patients exposed in vivo to ultrasound was also analyzed in multiple experiments. Reproducible chromosome aberrations could not be found in any of the studies. In contrast, many experiments on pregnant rodents showed some significant complications, such as abortion, deformities, and behavioral disorders. As in the case of thermal effects, the results of these experiments indicate the presence of an intensity- or pressure-dependent effect threshold. Numerous epidemiological studies examining possible short-term and long-term consequences after intrauterine ultrasound exposure are available with the most important studies being discussed in the following. In contrast to information presented incorrectly in the secondary literature and in the lay press, health problems could not be seen in the children observed in the postpartum period in any of these studies.

How Safe Is the Use of Ultrasound in Prenatal Medicine? Facts and Contradictions. Part 1 - Ultrasound-Induced Bioeffects

The "Ordinance on Protection Against the Harmful Effects of Non-Ionizing Radiation in Human Applications" will go into effect at the beginning of 2021 1. § 10 of this ordinance prohibits non-medical fetal ultrasound exposure thereby resulting in uncertainty, particularly among affected patients, with respect to the generally accepted theory regarding the lack of ultrasound side effects. Although not a single study has shown a detrimental effect on fetal or child development following exposure to ultrasound, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety has justified the ban with the purely hypothetical possibility of an unidentified side effect. The first part of the following study shows which ultrasound-induced biophysical effects are known and which dose-dependent threshold values must be taken into consideration. In particular, the study focuses on the well-researched heat effect with some in vivo measurements in humans showing that the actual temperature increase is less than the theoretically calculated values. The planned second part of this study will discuss the non-thermal effects and present the most important epidemiological studies.

DEGUM Recommendations on Infection Prevention in Ultrasound and Endoscopic Ultrasound

Microbial contamination of ultrasound probes for percutaneous or endoscopic use is common. However, infectious diseases caused by transmission of microorganisms by US procedures have rarely been reported. In Germany, legal regulations address hygiene in ultrasound procedures. Based on these regulations and the available literature, an expert panel of the German Society of Ultrasound in Medicine (DEGUM) has formulated sophisticated recommendations on hygienic measures in percutaneous and endoscopic US, including US-guided interventions.

[Comparative ultrasound visualization of clinically relevant structures for evaluating the infant hip joint utilizing trapezoidal vs. parallel transducers]

PURPOSE

Sonographic evaluation of the infant hip joint according to the method of Graf has proven to be an important pediatric investigative instrument. Our goal was to investigate quantitatively whether (and in what ways) the clinically relevant infant hip joint structures visualize differently when utilizing trapezoidal as opposed to linear transducers. Our approach was both theoretical via a mathematical model and practical with in-vivo measurements in neonates.

MATERIALS AND METHODS

In a prospective study: 1. theoretical and computed analyses were performed for both linear and trapezoidal transducers regarding their respective accuracy for demonstrating the anatomic geometry of the infant hip, assuming not only correctly centered transducer positioning but also cases with off-centered displacement in the cranial or caudal direction; 2. both hip joints in 97 infants were examined by experienced investigators with comparison of the results for parallel vs. trapezoidal transducers.

RESULTS

Theoretical mathematical error analysis reveals no intrinsic systemic deviations between trapezoidal vs. parallel transducers in US scanning of the infant hip and furthermore no inherent disadvantages in the trapezoidal technique. Even when off-center transducer alignments of 1.5 cm are employed in the mathematical models, there is no significant relative distortion of the required anatomic structures when comparing the characteristics of both transducers. The practical in-vivo data from our 97 neonates confirmed the theoretical considerations.

CONCLUSION

No loss of accuracy or other negative factors are evident when trapezoidal transducers are used to visualize the infant hip joint in comparison with the customary parallel technique. There are no significantly measurable differences between the two approaches.

Prospektiver Vergleich verschiedener Ultraschallverfahren zur Dickenmessung im Grenzbereich von Dicken unter 1 Millimeter

PURPOSE

New ultrasound techniques with improved visualization and better transducers constantly expand the methods of measurement. In the border area in the case of thickness measurements of less than 1 millimeter, e. g. the measurement of the "Intima-Media Thickness" (IMT), it is not clear if better visualization comes at the price of incorrect measurement values. We checked different modalities for accuracy and visualization quality.

MATERIALS AND METHODS

We prospectively examined the IMT of obese children using different ultrasound modalities. The image quality was evaluated by two independent pediatric radiologists. A phantom with an exact thickness of 0.3 mm (value of the thinnest measured IMT thickness) was subsequently created by precision engineers. Measurements were carried out and analyzed using fundamental ultrasound, tissue harmonic imaging, speckle reduction imaging and cross beam (real-time compound) imaging.

RESULTS

The best image quality was reached using speckle reduction imaging. This technique and fundamental ultrasound produced the most exact data. However, the recognizability was worse in fundamental ultrasound than in speckle reduction imaging.

CONCLUSION

Speckle reduction imaging appears to be the best technique for measuring thicknesses less than 1 mm.

[Sonographic artifacts of round reflectors]

The appearance of the proximal curved edge artifact using linear-array systems is demonstrated in five cases. Furthermore simulation of this artifact was achieved in a waterbath. A physical explanation of this phenomenon is discussed.

[Methods for discriminating flow direction with continuous wave Doppler equipment]

The application of ultrasound Doppler units for the localization of incompetent venous valves, the examination of extracranial vessels, and the evaluation of the hemodynamic effect of certain cardiac dysfunctions requires directional models with the possibility of recording Doppler wave forms. Various techniques are used to determine flow direction all of them presenting specific advantages and disadvantages in practical use. After briefly explaining the basic Doppler technique, the three most commonly used methods, the two-channel filter technique, the McLeod system, and the outphaser system, are described. The characteristics of the various signal processing techniques are discussed, particularly in the case of complex hemodynamic conditions.