Bioeffects Of Ultrasonography

Magnetic Field Bioeffects

Ultrasound-induced Fetal Bioeffects

When diagnostic ultrasound started being used more routinely for fetal imaging in the 1970’s, it motivated an interest in the question of whether diagnostic ultrasound might induce biological effects in the fetus. As a result a great number of studies, primarily in animal models, have been performed over the last 30+ years to investigate the possible effects of in utero ultrasound exposure. The...

Bioeffects considerations for diagnostic ultrasound contrast agents.

Diagnostic ultrasound contrast agents have been developed for enhancing the echogenicity of blood and for delineating other structures of the body. Approved agents are suspensions of gas bodies (stabilized microbubbles), which have been designed for persistence in the circulation and strong echo return for imaging. The interaction of ultrasound pulses with these gas bodies is a form of acoustic...

Magnetic resonance imaging: bioeffects and safety concerns.

Magnetic resonance imaging (MRI) is the state-of-the-art noninvasive imaging modality in clinical diagnosis. During MRI examination, the patient is exposed to three different forms of electromagnetic radiation: (i) a static magnetic field, (ii) gradient magnetic fields, and (iii) radiofrequency (RF) fields. Each of these may cause significant adverse bioeffects if applied at sufficiently high e...

Nonlinearities in the Bioeffects of Ultrasound

Biological effects of ultrasound involve nonlinear phenomena in qualitatively different ways. (1) The propagation of sound itself is nonlinear. Most nonthermal bioeffects of interest to users of diagnostic ultrasound require acoustic pressures great enough that the wave becomes distorted by nonlinear propagation. Under 1imi ting conditions this process can increase the absorption parameter of w...