Status of and trends in nuclear medicine in the United States.

Nuclear medicine in the United States has grown because of advances in technology, including hybrid imaging, the introduction of new radiopharmaceuticals for diagnosis and therapy, and the development of molecular imaging based on the tracer principle, which is not based on radioisotopes. Continued growth of the field will require cost-effectiveness data and evidence that nuclear medicine procedures affect patients' outcomes. Nuclear medicine physicians and radiologists will need more training in anatomic and molecular imaging. New educational models are being developed to ensure that future physicians will be adequately prepared.