Imaging tests provide a picture of the body’s interior—of the whole body or part of it. Imaging helps doctors diagnose a disorder, determine how severe the disorder is, and monitor people after the disorder is diagnosed. Most imaging tests are painless, relatively safe, and noninvasive (that is, they do not require an incision in the skin or the insertion of an instrument into the body).
Imaging tests may use the following:
Radiation, as in x-rays Plain X-Rays X-rays are high-energy radiation waves that can penetrate most substances (to varying degrees). In very low doses, x-rays are used to produce images that help doctors diagnose disease. In high... read more , angiography Angiography In angiography, x-rays are used to produce detailed images of blood vessels. It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography and magnetic... read more , computed tomography Computed Tomography (CT) In computed tomography (CT), which used to be called computed axial tomography (CAT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually... read more
(CT), and radionuclide scanning Radionuclide Scanning In radionuclide scanning, radionuclides are used to produce images. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more including positron emission tomography Positron Emission Tomography (PET) Positron emission tomography (PET) is a type of radionuclide scanning. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more 
(PET)Substances that are swallowed, injected, or inserted to highlight or outline the tissue or organ to be examined (called contrast agents Radiographic Contrast Agents During imaging tests, contrast agents may be used to distinguish one tissue or structure from its surroundings or to provide greater detail. Contrast agents include Radiopaque contrast agents... read more )
There are some risks of using radiation Risks of Radiation in Medical Imaging Imaging tests that use radiation, usually x-rays, are a valuable tool in diagnosis, but exposure to radiation has some risks (see also Radiation Injury). Different diagnostic tests require different... read more in medical imaging.
For information regarding imaging tests common for specific diagnoses and screenings, see the following:
Brain, Spinal Cord, and Nerve Disorders Tests for Brain, Spinal Cord, and Nerve Disorders Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more
