What Is a Thallium/Myocardial Perfusion Scan?
A myocardical perfusion scan is one of several diagnostic procedures
used to diagnose and evaluate coronary
artery disease.
A thallium/myocardial perfusion scan is a type of nuclear medicine
procedure. It is used to assess the blood flow to the heart muscle
(myocardium) and to determine what areas of the myocardium have
decreased blood flow. It is given while the patient is at rest or
after exercise that may reveal areas of the heart muscle that are not
getting enough blood.
This is done by injecting a tiny amount of radioactive substance
called a "radionuclide" into a vein in the arm or hand to
assist in the examination of the tissue.
The tiny amount of radionuclide, also known as radiopharmaceutical or
radioactive tracer, travels through the blood stream and is taken up
(absorbed) by the healthy heart muscle tissue. The areas where the
radionuclide has been absorbed will show up differently than the areas
that do not absorb it (due to decreased blood flow to the area or
possible damage to the tissue from decreased or blocked blood flow).
There are different types of radionuclides. When one type of
radionuclide is used, areas of the myocardium that have blocked or
partially blocked arteries will be seen on the scan as "cold
spots," or "defects," because these areas will be
unable to take in the radionuclide into the myocardium.
Another type of radionuclide binds to the calcium that is released
when a heart attack occurs, so it will accumulate in area(s) of
injured heart tissue as a "hot spot" on the scan.
Other related procedures that may be used to diagnose heart disorders include: