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P&B Fahr wrote: > > I believe your statement should be that there can be no > "magnetic object" as opposed to "metal object". Many > metal objects are not magnetic such as aluminum, copper, > silver, gold, and stainless steel. I believe a metal > object has to contain iron or an iron alloy to be > magnetic. > the MRI scanner employs such a powerful field that the > subject can't have any > metal object on or in his body) Without entering a discussion of physics of little interest to other listmembers: In this case it's the shape rather than the material that is important. When the magnetic field around any electrical conductor changes, an electric current results (for example, the copper wire coils in a generator). If any metal object in your body happens to be the wrong shape, elongated or coiled, its current or internal heat might conceivably injure surrounding tissue. I've had MRIs despite numerous crowns and fillings in my teeth, without ill effect, but the MRI techs generally are cautious about any other internal metal. Cheers, Joe -- J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks, CA 91403-5013