Clinical Use of Cardiac Radionuclide Imaging

Radionuclides are elements of molecules that emit radiation.

Cardiac radionuclide imaging is the use of radionuclides--radioactive forms of certain chemical elements and compounds--together with special cameras known as gamma cameras to obtain information on the function of the heart. It can be used clinically to diagnose and assess various medical conditions.

Radionuclides

Radionuclides are used in the field of nuclear medicine.

Atoms and molecules that emit radioactivity are known as radionuclides. This radioactivity is in the form of subatomic particles or gamma rays. Depending on the type of emission and other characteristics of the radionuclide, different agents are useful in different clinical imaging procedures. In cardiac imaging, radionuclides are introduced into the body by injection. Gamma radiation, produced directly by the radionuclides or indirectly as a result of their presence, is then detected by special sensors. Data are then processed to produce an image.

Radionuclides Used in Cardiac Imaging

Radionuclides are useful in various cardiac tests.

Radionuclides used in cardiac imaging include technetium-99 and thallium-201. The number following the name of the element represents the total of the number of protons and neutrons in the nucleus of the element's atoms.

Uses of Radionuclide Imaging Specific to Cardiology

Radionuclides can be used in conjunction with electrocardiography.

Uses of radionuclides in assessing cardiac function include evaluation of myocardial perfusion; the flow of blood through the heart muscle (myocardium) is tracked as the sensors, known as gamma cameras, track radiation from the radionuclide flowing in myocardial blood vessels.

Another use is for the evaluation of coronary artery disease; in this case, the flow of radionuclides, and therefore the blood, is tracked through the coronary arteries, the main blood vessels that nourish the heart. Similarly, the extent of damage to the heart following a myocardial infarction (interruption of blood flow to an area of the heart muscle) can be evaluated, as can the improvement of blood flow after coronary artery bypass surgery.

Together with electrocardiography, radionuclides can be used to assess how well the heart muscle moves.

References

• Cleveland Clinic: Nuclear Imaging