Myocardial scintigraphy (also called myocardial perfusion imaging) is a medical imaging test used to analyze the functioning and vascularization of the heart by injecting a tracer (a low-level radioactive product). This product is not harmful to the patient’s health.
The tracer, injected intravenously, is absorbed by the various structures of the heart and releases radiation that is captured and analyzed by a scintigraphy (a camera). The camera detects the tracer concentration in the various parts of the heart and the radioactivity present is shown as pulses of light.
During a myocardial scintigraphy exam, the patient undergoes an exercise stress test, lasting around 15 minutes, on a treadmill or bicycle to increase blood flow and detect any abnormalities that cannot be detected without physical effort.
If the patient is unable to perform a stress test, medication to mimic the effects of physical effort is injected intravenously.
To establish a diagnosis, the doctor looks at:
- damaged or poorly irrigated areas that do not absorb the contrast product.
- healthy areas that absorb the product.
A myocardial scintigraphy may be combined with an electrocardiogram (ECG or EKG) to simultaneously record the heart rate while images are being acquired.
Myocardial scintigraphy is not painful and is not a dangerous examination; only a very low dose of radioactivity is injected.
Why have a scintigraphy exam?
A myocardial scintigraphy exam may be prescribed for the following reasons:
- Chest pain, severe shortness of breath,
- Suspicion of coronary heart disease (narrowing of the coronary arteries), angina pectoris or heart failure,
- After a myocardial infarction (heart attack) to evaluate the severity of the damage,
- To monitor the blood flow in the heart after coronary artery bypass grafting, angioplasty or stenting,
- To detect insufficient blood flow during physical effort,
- Etc.
How to prepare for it?
Myocardial scintigraphy does not require any particular preparation.
You will not necessarily be asked to fast (unless requested), however it may be recommended to not consume stimulants in the 48 hours preceding the examination (tea, coffee, energy drinks, etc.) or foods containing a high amount of potassium (bananas, vegetables, dried fruit and nuts).
If the patient is taking any medication, they should continue taking it, unless advised not to by a physician.
All jewelry and/or metal objects must be removed. Patients fitted with pacemakers can still undergo this test.
Lastly, comfortable clothing and sports shoes should be worn for the stress test.
Pregnant or breastfeeding women should not undergo a scintigraphy exam.
How does the exam take place?
The duration of the myocardial scintigraphy will depend on the type of examination performed:
- with a stress test,
- without a stress test,
- dynamic study.
The injection of the radioactive tracer is not painful and side effects are very rare. The level of exposure to radioactivity is the same as during X-ray examinations.
During a scintigraphy with administration of a medication mimicking physical effort, the patient may experience hot flashes, chest tightness, rapid-onset headache and digestive disorders.
- Myocardial scintigraphy with a stress test
First, a scintigraphy of the resting heart muscle is performed. The patient lies down on the examination table and a low dose of radioactive tracer is injected into the arm. Once the product has had time to thoroughly diffuse throughout the body (10 to 20 minutes), the patient lies down and the image acquisition phase begins for a duration of approximately 10 minutes.
Then the patient performs the stress test on a bicycle, during which time their heart rate is recorded. A new injection of radioactive tracer is administered at the peak of the physical effort.
A new image recording begins, in the same position as the first time, for 5 minutes.
The patient is then taken back to the waiting room, while the images are processed by a computer and analyzed by the physician.
The whole examination, including the wait time for the results, lasts approximately 3 hours.
- Myocardial scintigraphy without a stress test
When the patient cannot perform a stress test, medication is administered that mimics the effects of the stress test on the heart.
First, a scintigraphy of the resting heart muscle is performed. The patient lies down on the examination table and a low dose of radioactive tracer is injected into the arm. Once the product has had time to thoroughly diffuse throughout the body (10 to 20 minutes), the patient lies down and the image acquisition phase begins for a duration of approximately 10 minutes.
Then the patient is given the medication that replaces the stress test.
A new image recording begins (with a new injection of the radioactive product), in the same position as the first time, for 5 minutes.
The patient is then taken back to the waiting room, while the images are processed by computer and analyzed by the physician.
The whole examination, including the wait time for the results, lasts approximately 3 hours.
- Myocardial scintigraphy with dynamic study
In this specific case, a scintigraphy of the resting heart muscle is first performed. The patient lies down on the examination table and is given two radioactive tracer injections in the arm. Then the patient lies down and the image acquisition phase begins for a duration of around 10 minutes.
Then, the patient is given medication that mimics a stress test and another injection of the radioactive tracer.
A new image recording begins when the medication is administered, in the same position as the first time and for 10 minutes.
The patient is then taken back to the waiting room, while the images are processed by a computer and analyzed by the physician.
The whole examination, including the wait time for the results, lasts approximately 1 hour and 30 minutes.
What are the post-examination recommendations?
The contrast agent has no known side effects, and does not cause discomfort or drowsiness. The patient can therefore drive after the exam.
In general, it is recommended to drink plenty of water to remove the tracer from the body more quickly. Apart from that, there are no special instructions; the patient can resume their activities.
Reviewed and approved by Marine Arnaud, MD, Cardiologist at Bordeaux University Hospital (CHU)
