Cardiac Nuclear Medicine
What is cardiac nuclear medicine?
Nuclear medicine is a type of medical imaging that uses small amounts of radioactive material to diagnose and treat a variety of diseases, including cancers, heart disease and other abnormalities within the body. Nuclear medicine is unique because it documents function as well as structure.
Nuclear medicine or radionuclide imaging procedures are noninvasive, and except the intravenous injections, are usually painless medical tests to help physicians diagnose medical conditions. These imaging scans use radioactive materials called radiopharmaceuticals or radiotracers.
What are common uses of the procedure?
Physicians use cardiac nuclear medicine studies to help diagnose cardiac disease in patients with these symptoms:
- unexplained chest pain
- chest pain brought on by exercise (angina)
Cardiac nuclear medicine imaging is also performed:
- to visualize blood flow patterns to the heart walls, called a myocardial perfusion scan.
- to evaluate the existence of suspected or known coronary artery disease.
- to determine the extent of heart injury following a heart attack, or myocardial infarction.
- to evaluate bypass surgery results or other revascularization procedures designed to restore blood supply to the heart.
- in conjunction with an electrocardiogram (ECG), to evaluate heart-wall movement and overall heart function.
Preparations for your Procedure
You may be asked to wear a gown during the exam or you may be allowed to wear your own clothing.
Women should always inform their physician or technologist if there is any possibility that they are pregnant or if they are breastfeeding.
You should inform your physician and the technologist performing your exam of any medications you are taking, including vitamins and herbal supplements. You should also inform them if you have any allergies and about recent illnesses or other medical conditions.
You should inform your physician if you have asthma, a chronic lung disease or have problems with your knees, hips or maintaining your balance, which may limit your ability to perform the exercise needed for this procedure.
Jewelry and other metallic accessories should be left at home or removed prior to the exam because they may interfere with the procedure.
You should avoid caffeine and smoking for 48 hours prior examination. Please review the list of caffeine containing products and medications.
||Regular or decaffeinated
||Regular or decaffeinated
||Regular or decaffeinated including Cola, Dr. Pepper, Mellow Yellow, Mountain Dew, Mr. Pibbv, Tab, Ginger Ale, Sprite, etc.
||Chocolate or cocoa containing products
||Anacin, Excedrin, NoDoz
||Cafegot, Darvon, Fiorinal, Synalog DC, Wigraine
If you are having a Adenosine (pharmaceutical) Stress Test, the following medications should be discontinued 48 hours prior to your test date. Please call the prescribing physician for permission to withhold these medications.
You should not eat or drink anything 4 hours prior to your procedure, but you may continue taking medications with small amounts of water unless your physician says otherwise. If you take beta-blocker medication (Inderal, metoprolol, etc.) you need to ask your physician about temporary discontinuation.
What is the equipment like?
Nuclear medicine procedures are usually performed using a specialized gamma camera encased in metal that is capable of detecting radiation and taking pictures from different angles. This camera is located within a large, doughnut-shaped scanner similar in appearance to a CT scanner and rotates around your body to produce more detailed images, referred to as Single Photon Emission Computed Tomography (SPECT).
The images are created from the data obtained by the camera or scanner aided by a computer.
How does procedure work?
Ordinary x-ray examinations are images made by passing x-rays through your body from an outside source. In contrast, nuclear medicine procedures use radioactive material called radiopharmaceutical or radiotracer, which is injected into your bloodstream. This radioactive material accumulates in the organ or examination area of your body, where it gives off a small amount of energy in the form of gamma rays. A gamma camera, PET scanner, or probe detects this energy and creates pictures offering details on the structure and function of organs and tissues in your body with the help of a computer.
In order to evaluate the coronary arteries, heart scans are often performed immediately after a stress test where patients have engaged in physical exercise so the blood flow throughout your heart is maximized, making any blockages of the coronary arteries easier to detect. These images of the heart are compared with heart images taken while the patient is at rest. Patients who are unable to exercise are given adenosine which increases blood flow to the heart.
How is procedure performed?
To obtain the best results possible, the study should be performed over 2 days.
On Day 1, you will receive an injection of the radiotracer into a vein. Approximately 20-40 minutes after the tracer injection, you will lie on a moveable imaging table with your arms over your head for about 15-20 minutes while images are recorded.
On Day 2, a nurse or technologist will insert an IV line into a vein in your hand or arm. You will then undergo a stress test which requires you to exercise by walking on a treadmill. While you exercise, the electrical activity of your heart will be monitored by ECG and your blood pressure is measured frequently. If you are unable to use a treadmill, you will be given the drug adenosine to increase blood flow to your heart. When blood flow to the heart has reached its peak, the radiotracer will be given through your IV. After you complete the stress test, you may be asked to drink some water. Approximately 20-40 minutes later you’ll be placed on the imaging table a second time so another series of images can be recorded.
Actual scanning time for each heart scan is approximately 15 minutes. Total time in the nuclear medicine department is estimated to be 45-60 minutes each day. Your IV line will be removed prior to going home.
What will I experience during and after procedure?
Most nuclear medicine procedures are painless, except the intravenous injections, and you rarely experience significant discomfort or side effects.
You will feel a slight pin prick when the needle is inserted into your vein for the intravenous line when the radiotracer is given intravenously. You may feel a cold sensation moving up your arm, when the radioactive material is injected into your arm, but there are generally no other side effects.
You will be asked to exercise until you are either too tired to continue, short of breath, or experiencing chest pain, leg pain, or other discomfort that makes you to want to stop.
If you are given Adenosine to increase blood flow because you are unable to exercise, the medication may induce a brief period of nausea, anxiety, dizziness, shaky, or short of breath. Mild chest discomfort may also occur. Any symptoms that develop typically resolve as soon as the infusion is complete. If the side effects of the medication are severe or make you too uncomfortable, other drugs can be given to stop side effects.
It is important that you remain still while images are recorded. Though nuclear imaging itself causes no pain, there may be some discomfort from remaining still or staying in one particular position during imaging.
Unless your physician tells you otherwise, you may resume normal activities after your nuclear medicine scan. If any special instructions are necessary, you will be informed by a technologist, nurse or physician before you leave the nuclear medicine department.
Through the natural process of radioactive decay, the small amount of radiotracer in your body will lose its radioactivity over time. It may pass out of your body through your urine or stool during a few hours or days following the test. You may be instructed to take special precautions after urinating such as flushing the toilet twice and washing your hands thoroughly. You need to drink plenty of water to help flush the radioactive material out of your body.
Who interprets the results?
A nuclear-trained cardiologist will interpret the images and forward a report to your referring physician.