FDA relaxes rules on ultrasound in COVID-19

The FDA carved out a special section of the guidance for ultrasound systems, which have become useful in diagnosing patients with COVID-19. The agency said that because ultrasound scanners do not emit ionizing radiation, the FDA believes users can have "additional flexibility," with modifications allowed under the following circumstances:

• Modifications that would allow an ultrasound scanner to be used outside of the environment for which it is cleared, such as a general practitioner's office or a field hospital
• Changes that would enable the acquisition of images by healthcare practitioners who are not trained in sonography, under appropriate supervision
• The addition of lung scanning clinical applications, as long as labeling is included that is based on established practice guidelines, such as from the American Institute of Ultrasound in Medicine (AIUM)
• The availability of probes and machine settings that are suitable for lung scanning, such as probes at a frequency of 3 MHz and higher, and with linear, curvilinear, and phased-array technologies
• The use of a mechanical index (MI) < 1.4 as an indicator for potential biological effects on tissues containing gas bodies

The agency would frown on ultrasound modifications as follows:

• Changes that would result in an increase of the derated maximum acoustic output parameters
• Modifications that would exceed known safety limits in humans, such as a MI ≥ 1.4 for lung images
• Modifications that would allow lay users to acquire images without guidance of healthcare practitioners.