BIOEFFECTS OF DIAGNOSTIC ULTRASOUND: HOW HAS RESEARCH PROGRESSED?

Dr Stanley B Barnett PhD FAIUM, Chair, ASUM Safety Committee, CSIRO, Sydney, Australia.

Introduction
The study of bioeffects of ultrasound has a fascinating history. It has been a quite fruitful area of research due, largely, to the dedicated efforts of small groups of researchers and the continued enthusiastic academic interactions. Early research, using relatively crude endpoints, looked for effects of ultrasound exposure at therapeutic levels, while later studies have been developed to evaluate potential effects from low-level diagnostic-type exposures. Interpretation of accumulated data forms the basis for the development of guidelines to ensure the continued safe and effective use of ultrasound in medicine. With the evolution to modern diagnostically powerful ultrasound imaging equipment the level of acoustic output has increased and pulsing conditions changed. The recent introduction of non-linear propagation in harmonic imaging increases diagnostic resolution but also adds a further level of complexity to bioeffects studies. The development of echo-contrast agents for use with diagnostic imaging introduces another risk factor that needs to be thoroughly investigated in terms of risk/benefit assessment.

Throughout the development of bioeffects research the essential value of mechanistic studies has been recognised. Nevertheless, the quest for knowledge has left some areas of bioeffects research with questions that remain unanswered. Some reports of adverse effects on embryonic and fetal development following diagnostic levels of exposure have been generally discounted due to absence of a plausible mechanism. On the other hand, low intensity pulsed ultrasound is used beneficially in therapeutic applications, while the mechanism of interaction is not fully understood. Science develops gradually through the spread of knowledge. Interest in continuing research on bioeffects and safety has been supported through various ultrasound organisations, notably the World Federation for Ultrasound in Medicine and Biology (WFUMB) which has played a vital role in publishing and encouraging the spread of scientific information on this topic.

Citation
Barnett S. Bioeffects of diagnostic ultrasound: How has research progressed? ASUM Bulletin 2001.4:17-19.