THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

502 17. Commercial and Medical Ultrasound Applicationshumans. This is clinically significant, because visualization of the myocardial flowpermits direct assessment of underperfused or unperfused regions (i.e., areas ofischemia or infarction) in patients with a history of chest pain. Myocardial imagingusing ultrasound contrast agents provides an assessment of the coronary arteriesand of the coronary blood flow reserve, as well as collateral blood flow that mayexist.Any body cavity that can be accessed can, in principle, be injected with vascularcontrast. According to Shi et al. (2005), the most successful application inthis category is hysterosalpingo-contrast sonography (abbreviated HyCoSy) forthe evaluation of fallopian tube patency. Degenhardt et al. (1996) reported on103 patients with fertility problems who underwent transvaginal sonography andHyCoSy with Echovist 14. In 58 cases, HyCoSy was compared with conventional,more invasive techniques such as chromolaparoscopy and 91% agreement wasfound. The upshot is that HyCoSy is rapidly becoming the screening test of choiceto determine tubal patency.Safety of Ultrasonic DiagnosisExtensive studies on the safety of ultrasound in Japan and elsewhere have led toissuance of Japanese industrial standards (JIS) for diagnostic ultrasound devices.These standards place limits on various diagnostic procedures:1. Ultrasonic Doppler fetal diagnostic equipment, 10 mW/cm 2 or less.2. Manual scanning B-mode ultrasonic diagnostic equipment, 10 mW/cm 2 or lessfor each probe.3. Electronic linear scanning B-mode ultrasonic diagnostic equipment,10 mW/cm 2 or less in a single aperture.4. A-mode ultrasonic diagnostic equipment, 100 mW/cm 2 or less: This standard islimited to diagnosis of the adult head and is not for pregnancy where B-mode isthe principal technique used. This higher permissible level is due to attenuationthrough the adult skull bone.5. M-mode ultrasonic diagnostic equipment, 40 mW/cm 2 or less: The M-mode isused in clinical diagnosis of the heart. For a combination of the M-mode withthe B-mode, the intensity is limited by the B-mode standard, i.e., 10 mW/cm 2 .In 2000, the Safety Group of the British Medical Ultrasound Society issued thefollowing statement on the safe use and potential hazards of diagnostic ultrasound(Ter and Duck, 2000): Ultrasound is now accepted as being of considerable diagnostic value. There isno evidence that diagnostic ultrasound has produced any harm to patients in thefour decades that it has been in use. However, the acoustic output of modernequipment is generally much greater than that of the early equipment and, inview of the continuing progress in equipment design and applications, outputsmay be expected to continue to be subject to change. Also, investigations into the