Thallium Stress Test

Thallium Stress Test is also known as a cardiac or nuclear stress test. It is a nuclear imaging test that tells about the flow of blood and oxygen into the heart when the body is under stress (which means it is in motion or is at rest). This imaging test also determines if any damage has happened to the heart in the past whether a cardiac event is about to happen or not. The ‘Thallium Stress Test’ can take about 1 to 2 hours to get completed that compares your heart working in the rest position in exercising mode.   

This Thallium Stress Test uses a Positron Emission Technology (PET) scanner or Single Photo Emission Computed Tomography (SPECT) scanner. A Myocardial Perfusion Imaging (MPI) is also known as a nuclear stress test, cardiac PET study, or cardiac SPECT study.

How to Perform Thallium Stress Test? 

This test must be performed in a hospital or a fully equipped medical facility along with a doctor, nurse, and a professional who can insert the intravenous (IV) line. 

The procedure starts by inserting an intravenous line, usually inside the elbow. Then a liquid is inserted through the IV line. This liquid is a radioactive substance, such as thallium or sestamibi, injected into the veins. Pictures are taken through a Gamma camera when the radioactive substance reaches the heart.  

The test has two portions. One is the resting portion, and another one is the exercise portion. Readings of the blood flow through the heart are noted for both parts, and the problem is identified. 

Resting Segment

While resting, the patient lies on the examination table for about 15 to 45 minutes. He is asked to put his arms above his head. The radioactive substance is passed through the veins to the heart, and pictures through a gamma camera are taken.

Exercise Segment

During this test segment, the patient is usually asked to do cycling or take a walk on a treadmill. The patient is asked to start from a slow mode and gradually go for a high-speed walk or go into jogging mode to increase heartbeat. 

If the patient cannot do the exercise, he is provided with medication to increase his heartbeat. It will help show how the patient’s heart will work while exercising. 

When the heart’s working reaches its maximum level, the patient is asked to stop doing exercise and lie down again on the exam table. And after about 30 minutes, the gamma camera will take pictures.  

Now, these results and results from resting segments will be compared and will identify if the heart is working correctly or not. 

Preparation before the Thallium Stress Test

Almost all kinds of tests require specific types of instructions regarding the patients to opt to perform the test and to get accurate findings. Similar is the case in this stress test. 

It is necessary to discuss your medical history with your doctor and your exercise routine so that the doctor can know what amount of exercise is best for you while conducting the test. 

 Instructions are provided to the patient before coming to the hospital for this test, which are as follows: 

  • Caffeine intake, including tea, soda, coffee, chocolate, or other energy drinks, should be avoided at least 24 hours before the test. Caffeine may affect the heartbeat rate. 
  • Avoid taking any sedative or pain reliever at least one day before the test.
  • Stop taking food at midnight or at least 4 hours before the test. 
  • Discuss if you are on any medication and if it may affect your test. 
  • If you have breathing issues or use an inhaler, bring it with you as you may need it while exercising.
  • Try to come to the hospital in comfortable clothes. 
  • Do not use cream, oils, lotions, or any balm on the day of the test.

Risk Factors 

It is not a full pain test, but sometimes, the patient observes a ticklish feeling when the radioactive material is inserted inside the body. In comparison, some patients may experience headaches, nausea, irregular heartbeat, increasing pain due to poor blood flow in the heart, difficulty breathing, asthma, variation in blood pressure, skin rashes, chest discomfort, or dizziness.

The radioactive substances that were inserted into the body come out after a while through urine. Generally, no side effects are observed in the patients due to the radioactive substance. However, staying away from children for up to 24 hours is advised.  

According to the research, patients aged between 45 to 64 might risk experiencing cardiovascular death or myocardial infarction patients aged 65 and above. 

In case of facing any complications, do tell your doctor or technician.  


The test results depend upon the patient’s age and medical history or if one is currently suffering from heart problems. 

  • If the result is normal during rest and exercising, the blood flow to the heart is normal. No further testing or medication is needed.
  • If the result is normal during resting segments and not up to the mark during the exercise, it means when the patient’s heart is under stress, it can’t perform correctly. In other words, it means some of the coronary arteries are damaged or might be blocked.   
  • If the result is not typical during both resting and exercising segments, the artery disease is severe, which may result in a heart attack. 
  • If some parts of the patient do not show traces of the radioactive substance, it means those parts have been damaged due to a heart attack or some other heart disease, resulting in a lack of blood flow into the heart.  


In case of patient’s abnormal results, the doctor may prescribe different testation or medication according to the patient’s need.