It is true images may be blurred in women who are obese, have smaller hearts, or large breasts. If you are obese or have large breasts, the extra tissue may muffle the radioactive energy of the tracer, making it appear that it is not being absorbed as well. This could cause a false positive result—the test indicates a problem but in reality there is none. There can be a false positive but modern nuclear stress tests include computer programs that correct for some of this blurring and muffling.