Food and Drug Administration ultrasound device regulation: the output display standard, the "mechanical index," and ultrasound safety.

The Food and Drug Administration has recently revised its guidelines regarding acoustic output on diagnostic ultrasound equipment to allow a new track for manufacturers to achieve approval to market diagnostic ultrasound equipment. It would move for the first time toward regulating instrumental output based on scientific bioeffect data. It would allow increased instrumental output in certain modes and at the same time mandate on-screen labeling of a "thermal index" or "mechanical index," coupled with a user education program on the significance of these indexes. The increased instrumental output allowed by these new guidelines may benefit adult echocardiography by allowing slightly more penetration and higher frequency/better resolution. However, a tradeoff is that echocardiographers need to understand more about how to perform an examination to decrease unnecessary patient exposure to ultrasound and more about ultrasound bioeffects, such as the theoretical potential for cavitation-related adverse effects in certain circumstances.