Nuclear Stress Test

Imaging the heart: What you need to know

What is a Nuclear Stress Test?

Nuclear Stress Test (Cardiac SPECT) is a test used to detect heart disease and identify blockages in the coronary arteries (coronary artery disease).

A small dose of radioactive material can be used to track blood flow to the heart muscle:

  • To determine if coronary artery disease is present and if further studies and/or treatment are required
  • To evaluate progress following a major cardiac event (heart attack, heart surgery)
  • To evaluate whether a blockage found during an angiogram requires angioplasty
  • To follow the progress of documented coronary artery disease

Prior to your test:

  • Do not take any caffeinated or decaffeinated beverages or food at least 24 hours prior to your test (i.e. NO coffee, tea, soda, chocolate, energy drinks or headache-specific medications starting the day before your test).
  • Do not eat or drink after midnight or within 6 hours before your test; except water, juice or milk for taking medications.
  • Continue all your medications as prescribed unless otherwise instructed by your physician or nurse.

Nuclear Stress Test Locations in Houston, TX

Texas Medical Center

6410 Fannin St, Ste 600
Houston, TX 77030-5206


6700 West Loop S, Ste 540
Bellaire, TX 77401

Bayshore MS / Clearlake

11476 Space Center Blvd
Houston, TX 77059-3656

If you must cancel or reschedule, please do so at least 24 hours before your appointment.

SPECT Scan FAQ and Information:

  • A cardiac Single Photon Emission Computed Tomography (SPECT) scan is a non-invasive procedure that can be used to accurately identify areas of abnormal myocardial perfusion, determine the functional capacity of your heart muscle, and separate viable (living) from non-viable (irreversibly damaged) tissue.
  • In the evaluation of myocardial perfusion, or blood flow through the coronary arteries, the SPECT scan may require both a resting test and a stress test.
  • The stress test is performed either by treadmill exercise or with medication designed to induce blood flow as if exercising, such as in cases where the patient cannot walk or run on the treadmill.
  • The cardiac SPECT scan can identify areas of the heart which do not receive adequate blood flow during stress, called ischemia, as well as find areas of irreversibly damaged heart, or scarring.
  • Blood flow through the coronary arteries is typically adequate at rest, even in partially blocked vessels.
  • Under conditions of stress, such as during administration of certain medications or while on a treadmill, blood flow in a narrowed artery is significantly reduced.
  • By comparing the images of blood flow during rest and stress from the cardiac SPECT scan, a cardiologist can accurately determine whether patients have coronary blockages (stenosis), scarring (due to prior heart attack), or normal perfusion, function, and viability.
  • SPECT perfusion imaging can also measure the function of the heart muscle. Knowing how the heart works can be an important independent predictor of future events.
  • For 6 hours before your test, do not eat or drink (except water, juice, or milk, or your regular medications (except those containing caffeine)).
  • For 24 hours prior to your study, refrain from smoking and ingesting products that contain caffeine, including foods, beverages, and medications.
  • If you are claustrophobic, inform your physician/nurse prior to scheduling your test.
  • If you have diabetes, be sure to mention your diabetes to your physician and call the imaging center staff 48 hours before your scan.
  • If you are pregnant or think you may be, be sure to discuss this with your physician. Generally, SPECT scans are not performed on pregnant women.

Generally, SPECT scans are considered safe. There are no recognized allergic reactions or side effects related to injection of the radioactive solutions . The radiation exposure from the test is very small—equivalent to that of several chest x-rays—and has not been associated with any significant health risk, though as a precaution, the test is generally not performed on certain types of patients (such as pregnant women).

  • Bring something to read for waiting times.
  • Wear warm, comfortable clothes. The scanner room is cold to most.
  • Wear walking shoes or sneakers if you are scheduled to walk/run on the treadmill.
  • After registering, you will go to a preparation area where a nuclear medicine technologist will insert an IV access into your arm.
  • A radiopharmaceutical will be injected into the IV. After a waiting period you will be taken to the imaging room to obtain images of your heart at rest.
  • You will then be taken to the stress room where you will be connected to a monitoring computer.
  • You will be instructed on the proper technique for walking on the treadmill and the exam will be explained.
  • If you cannot walk/run on the treadmill, usually a medication that is designed to increase blood flow as if exercising will be injected through the IV.
    • During the infusion of the stressing medication, you may experience flushing, shortness of breath, chest pressure, lightheadedness, or nausea. This is temporary and disappears within seconds of completion of the infusion. Some patients experience no symptoms at all.
  • Once you have reached the desired heart rate during the stress test (whether by exercise or through medication) , you will receive another radiopharmaceutical injection.
  • Following another waiting period, you will return to the imaging room to obtain the second image of your heart.
  • The entire procedure typically lasts 3-4 hrs.
  • Please arrive 20 to 30 minutes before your scheduled appointment to complete the necessary paperwork, including a consent form required for all nuclear medicine exams.
  • If you must cancel or reschedule, please do so at least 24 hours before your appointment.
  • Generally, you can leave immediately after your scan.
  • Your activity will be generally unrestricted. You may drive if you wish, resume your normal diet, exercise, and take all prescribed medications.
  • The cardiac SPECT scan will be reviewed by a physician who will send a report to your doctor.
  • Your doctor will contact you about the results of your SPECT scan.
  • If you are planning air travel within 24 hours after your test, please inform your technologist. Sometimes, the nuclear medicine in your system can cause problems with X-ray scanners at airports. We can provide you with a travel document to assist in your travels.