In conventional diagnostic imaging, an external source of energy such as x-rays, magnetic fields or ultrasound waves is used to produce pictures of bone and soft tissue. In nuclear medicine and molecular imaging procedures, the energy source is introduced into the body, where it gets incorporated in a specific tissue, organ or process and is then detected by an external device (gamma camera, SPECT or PET scanners) to provide information on organ function and cellular activity. Because disease begins with microscopic cell changes, nuclear medicine and molecular imaging have the potential to identify disease in an earlier, more treatable stage, often before conventional imaging and other tests are able to reveal abnormalities.

To obtain this unique information without nuclear medicine and molecular imaging tests would require more invasive procedures—such as biopsy or surgery—or would simply be unattainable.

With their ability to identify the early signs of disease and other abnormalities, nuclear medicine and molecular imaging offer the potential to change medical care from reactive to proactive, saving and improving
countless lives.