MR safety: past, present, and future from a historical perspective.

This article focuses on both static field effects and oscillating magnetic fields associated with MR imaging and spectroscopy. Contemporary experiments and theories on health effects demonstrate that currently MR imaging is practiced in a safe manner. Technological capabilities and medical science objectives, however, will lead to procedures that will challenge the thresholds of physiological effects. Thus progress in this field will require continual surveillance and better definitions of guidelines which at present are considered prudent but too restrictive.