Ultrasound is extensively used in medical imaging, being safe and inexpensive and operating in real time. Its scope of applications has been widely broadened by the use of ultrasound contrast agents (UCAs) in the form of microscopic bubbles coated by a biocompatible shell. Their increased use has motivated a large amount of research to understand and characterize their physical properties as well as their interaction with the ultrasound field and their surrounding environment. Here we review the theoretical models that have been proposed to study and predict the behavior of UCAs. We begin with a brief introduction on the development of UCAs. We then present the basics of free-gas-bubble dynamics upon which UCA modeling is based. We review extensively the linear and non-linear models for shell elasticity and viscosity and present models for non-spherical and asymmetric bubble oscillations, especially in the presence of surrounding walls or tissue. Then, higher-order effects such as microstreaming, shedding and acoustic radiation forces are considered. We conclude this review with promising directions for the modeling and development of novel agents.

The appearance of ultrasound images depends critically on the physical interactions of sound with the tissues in the body. The basic principles of ultrasound imaging and the physical reasons for many common artifacts are described.

This article reviews the existing literature on diagnostic and medical imaging of pregnant women, the risks and safety measures of different medical imaging modalities, and alternative modalities for imaging pregnant patients. Different medical imaging modalities such as MRI, CT scan, ultrasound, nuclear medicine, and X-ray imaging help to evaluate women with recognized or unrecognized pregnancies and identify any underlying complications among pregnant patients. Fetuses are more sensitive to radiation and the effects of medical imaging as compared to adults since they have a rapidly developing cell system. During cell proliferation, migration, and differentiation, fetuses suffer greatly from imaging radiation since they are developing under a dynamic system. To ensure safety, pregnant women should discuss the benefits and risks of medical imaging with their physicians. In addition, radiologists should not perform any medical imaging procedure without the patient’s consent, unless the patient cannot make any sound decision. Fetal risks of medical imaging include slow growth and development of the fetus, abortion, malformations, impaired brain function, abnormal childhood growth, and neurological development. Diagnostic imaging procedures are necessary when a condition that needs medical evaluation arises during pregnancy such as appendicitis.

Abstract Introduction Successful placentation is crucial for fetal development and maintaining a healthy pregnancy. Placental insufficiency can cause a variety of obstetric complications. Despite the many efforts to enhance diagnosing placental insufficiency, no imaging technique has proven satisfactory. A promising imaging technique is contrast-enhanced ultrasound (CEUS) using microbubbles which has proven capable of (micro)vascular imaging. Its use for placental vascularization assessment in human pregnancies remains constrained by limited evidence and safety concerns. This scoping review aims to demonstrate the safety of CEUS used in human pregnancy in the published literature to date. Material and Methods A systematic search using PubMed, Medline, Embase, and Cochrane databases was performed. All studies where contrast-enhanced ultrasound was used in pregnant humans were included. Studies, where there was a planned termination of pregnancy, were excluded. To assess the safety of CEUS during pregnancy, relevant outcomes were divided into the following 3 categories; fetal outcome, maternal outcome, and pregnancy and neonatal outcomes. Results A total of 13 articles were included, in which 256 women underwent CEUS during pregnancy. No clinically significant maternal or fetal adverse events or negative pregnancy or neonatal outcomes associated with CEUS were described. Conclusion Based on our findings, we consider expanding the knowledge of this promising diagnostic technique in future larger clinical studies to be safe and relevant.

Background/Objectives: Obstetric ultrasound is one of the most commonly used imaging modalities during pregnancy to detect any fetal abnormalities. The aim of this systematic review was to appraise all available scientific literature and summarize current evidence regarding the safety of fetal ultrasound by using the thermal index (TI) and mechanical index (MI). Methods: We applied the PRISMA guidelines in order to prepare the review, and a 2-step process was performed in order to evaluate the available literature and decide which studies to be included. A thorough search of the Medline, Scopus, and Google Scholar databases was performed. Randomized and non-randomized studies were considered for review. The MI and TI were available in ultrasound machines after 1993; thus, studies before that year would not provide data on these two indexes. Results: A total of 21 studies were included in this review, including prospective, retrospective, cross-sectional, and survey-type studies. A common theme of the majority of the studies is the increased acoustic output available to the machines with time and the limited awareness of where the MI/TI indexes are from the operators. Conclusions: This review indicates that, while obstetric ultrasound is predominantly safe, there is a need for operators to consistently observe MI/TI indexes and adhere to the ALARA principle to minimize potential risks.

As medical imaging continues to expand, concerns about the potential risks of ionizing radiation to the developing fetus have led to a preference for non-radiation-based alternatives such as ultrasonography and fetal MRI. This review examines the current evidence on the safety of MRI during pregnancy, with a focus on 3 T MRI and contrast agents, aiming to provide a comprehensive synthesis that informs clinical decision-making, ensures fetal safety and supports the safe use of all available modalities that could impact management. We conducted a comprehensive review of studies from 2000 to 2024 on MRI safety during pregnancy, focusing on 3 T MRI and gadolinium use. The review included peer-reviewed articles and large database studies, summarizing key findings and identifying areas for further research. Fetal MRI, used alongside ultrasound, enhances diagnostic accuracy for fetal anomalies, particularly in the brain, thorax, gastrointestinal and genitourinary systems, with no conclusive evidence of adverse effects on fetal development. While theoretical risks such as tissue heating and acoustic damage exist, studies show no significant harm at 1.5 T or 3 T, though caution is still advised in the first trimester. Regarding gadolinium-based contrast agents, the evidence is conflicting: while some studies suggest risks such as stillbirth and rheumatological conditions, animal studies show minimal fetal retention and no significant toxicity, and later clinical research has not subst

Both ultrasound and MRI are recognized as generally safe imaging modalities and thus appropriate to be used in the diagnostics of the pregnant females and fetuses. However, to some extent, both techniques may carry some risks when used during pregnancy. To keep the fetus safe, knowledge of potential bioeffects is mandatory, as is understanding the background and the influence of particular factors for safety.

ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound. The usage of Sonography (ultrasonography) is widely used in medicine. It is possible to perform both diagnosis and therapeutic procedures, using ultrasound to guide interventional procedures such as biopsies or to drain collections of fluid, which… Most structures of the neck, including the thyroid and parathyroid glands, lymph nodes, and salivary glands, are well-visualized by high-frequency ultrasound with exceptional anatomic detail. Ultrasound is the preferred imaging modality for thyroid tumors and lesions, and its use is important in the evaluation, preoperative planning, and postoperative surveillance of patients with thyroid cancer. Many other benign and malignant conditions in the head and neck can be differentiated, evaluated, and managed with the help of diagnostic ultrasound and ultrasound-guided procedures. In oncological practice of medical contrast ultrasonography, clinicians use 'parametric imaging of vascular signatures' invented by Dr. Nicolas Rognin in 2010. This method is conceived as a cancer aided diagnostic tool, facilitating characterization of a suspicious tumor (malignant versus benign) in an organ. This method is based on medical computational science to analyze a time sequence of ultrasound contrast images, a digital video recorded in real-time during patient examination. Two consecutive signal processing steps are applied to each pixel of the tumor: "Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion". Diagnostic ultrasound studies of the fetus are generally considered to be safe during pregnancy. However, this diagnostic procedure should be performed only when there is a valid medical indication, and the lowest possible ultrasonic exposure setting should be used to gain the necessary diagnostic information under the "as low as reasonably practicable" or ALARP principle. Although there is no evidence that ultrasound could be harmful to the fetus, medical authorities typically strongly discourage the promotion, selling, or leasing of ultrasound equipment for making "keepsake fetal videos".

Grey-scale ultrasound imaging: assessment of acute hydronephrosis. Rapid changes in the renal anatomy during the development and resolution of an acute hydronephrosis may require multiple imaging procedures. The ionising radiation hazard limits the extent to which this may be achieved by intravenous pyelography. Grey-scale ultrasound offers a safe, non-intrusive technique for visualising the renal pelvis which may be repeated daily. The value of such an ultrasound facility is illustrated by 3 case histories. Published in British journal of urology (1975)

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