Assessment and approval of medical devices used in diagnostic imaging in the United States.

Development of new and improved medical imaging technology has been increasing rapidly over the past two decades. While media attention has focused on the revolutionary advances, such as computed tomography, magnetic resonance imaging and metabolic assessment by positron emission tomography, important progress has also been made in the more conventional modalities, including contrast radiography, ultrasound, scintigraphy and mammography. These evolutionary developments have produced fundamental changes in the character of imaging information and in the methods of its acquisition, storage, manipulation, analysis and display. The assessment process-vis-à-vis safety, effectiveness, efficacy or cost-has moved from a previously well-defined physical and engineering evaluation to one of assessing quality, relevance and appropriateness of the "information." A regulatory scheme has evolved in the U.S., whereby the Food and Drug Administration (FDA) is responsible for assuring that new medical devices be approved for commercial distribution only if their safety and effectiveness can be assured. Clear distinctions should be drawn between the FDA "approval" process, assessment of clinical efficacy, and planning for health care delivery.