Overview and Benefits
Heart imaging with position emission tomography is a form of imaging test. Also called cardiac PET scan, it is used to assess how well the heart is working. It involves injecting glucose solution into a vein in the arm, which is highlighted under a PET scanner. The images can tell doctors how well the blood flows through the heart. They can also help doctors measure oxygen use and how well the body is using glucose (damaged cells take up more glucose than normal cells).
Such information is key to diagnose a number of heart diseases. It can also help doctors decide if certain heart procedures will benefit the patient. The test is often performed before a patient undergoes angioplasty or coronary artery bypass surgery. PET scan show cells or tissues of the heart that can still be saved. If they are still functioning, patients are cleared for certain medical procedures.
Cardiac PET is an outpatient procedure. This means that patients are allowed to go some the same day.
Who Should Undergo and Expected Results
A cardiac PET scan is one of the diagnostic tests used by doctors to diagnose patients showing signs of heart problems. These signs include chest pains, arrhythmia, breathing difficulty, fatigue, and weakness.
Before a cardiac PET scan is ordered, patients undergo a number of tests first. These include a physical exam, a test that records the heart’s electrical signal (ECG), and stress test. If the results of initial tests suggest an abnormality, the doctor will order imaging tests. Aside from PET, other tests such as a computed tomography (CT) scan and magnetic resonance imaging (MRI) may also be used.
As for the expected results, the doctor will obtain crucial information to make a diagnosis. The images produced by PET scan will help them identify which areas of the heart are damaged or contain scar tissue. The images can also identify the areas of the heart that are not receiving enough supply of oxygen.
A PET scan can help diagnose coronary artery disease (CAD) and heart failure. CAD refers to a condition in which the arteries that carry blood to the heart are narrowed or blocked. Such condition is treated by widening the affected blood vessels with procedures such as angioplasty or bypass surgery. Heart failure, on the other hand, means that the heart is unable to pump efficiently. As a result, the body does not receive enough supply of oxygen and nutrients. It can be caused by a heart attack and heart valve disease.
How is the Procedure Performed?
Prior to the test, the patient is advised to make necessary preparations. They must submit a list of all the medications they are currently taking. The doctor will review the list to make sure that the medications will not affect the results of the PET scan. Patients with diabetes must consult their endocrinologist especially if they are on insulin therapy. Their dosage may need to be adjusted prior to the test. Patients are not allowed to eat anything four to six hours before the test.
PET scan is carried out by a nuclear medicine technologist. The test can be performed in a hospital or a specialised, fully equipped cardiac centre. The patient will be asked to lie down as electrodes that are connected to an ECG machine are placed on his or her chest, legs, and arms.
The radioactive material is then injected to the patient’s vein. The doctor will wait until the tracer reaches the heart muscle before the patient is placed inside a PET scan. The tracer is highlighted by the PET scanner. The information is then converted into pictures of the heart at work.
The test is done on an outpatient basis. This means that patients are allowed to go home after the procedure. They are advised to increase their water intake. This helps flush out the radioactive material from the body. They are then scheduled to come back within a couple of days wherein their doctor will explain the result of the test and the next steps that need to be taken.
Potential Risks and Complications
A PET scan is a nuclear imaging test that uses radioactive materials to create images of body organs. The amount of radioactive material used is very small and patients are exposed to low levels of radiation during the test. The risks of complications are thus small. The benefits of the procedure also outweigh its risks.
Some potential side effects are bleeding at the site where the radioactive material was injected and allergic reactions to the tracer. It is important to note that such risks rarely occur.
The American Heart Association. http://www.heart.org/HEARTORG/Conditions/HeartAttack/DiagnosingaHeartAttack/Positron-Emission-Tomography-PET_UCM_446359_Article.jsp#.WiXqM7T1VE4
Positron emission tomography — Computed tomography (PET/CT). Radiological Society of North America. http://www.radiologyinfo.org/en/info.cfm?pg=PET.
About nuclear medicine and molecular imaging. Society of Nuclear Medicine and Molecular Imaging. http://www.snmmi.org/AboutSNMMI/Content.aspx?ItemNumber=6433&navItemNumber=756.