Today our topic of discussion is Procedure of Thallium Testing.
Procedure of Thallium Testing
Procedure
- Thallium or adenosine is given intravenously about a minute before the completion of the stress test
- After the completion of the stress test, the client is placed supine on the table and multiple scintigraphic images are taken.
- The perfusion scanning is performed with a special camera that is capable of showing the source of emitted camera that is capable of showing the source of emitted low-energy photons on a screen
- Each photon detected by the camera is recorded on film and a computer screen over a half-hour period
- The computer refines and enhances the images and then provides qualitative information about the myocardial walls
- Two sets of images are taken 3 hours apart and compared
- Thallium can be given under a state of no physical demand, which is known as a resting thallium study, or it can be part of a stress test, in which case it is called exercise thallium imaging . .
- Exercise thallium imaging distinguishes ischemic sites from infarcted areas
- Thallium scans are repeated, once during stress testing and then 3-4 hours after thallium was given and the stress test was completed
- With the second imaging, if a cold spot disappears, it is recognized as an ischemic area.
Findings
- Cold spots indicate and distinguish areas of infarction and ischemia.
- High concentration of thallium 201 is present in well-perfused cells, and a lower concentration remains in the blood, setting up a concentration gradient for the diffusion on thallium 201
- Infarcted or scarred myocardium does not extract any thallium 201 showing up as cold spots.
- If the defective area is ischemic, the cold spots fill in or become warm on the delayed images.
After Care
- Assess the client’s response
- Three to four hours later, the client returns for repeat films
Complication
Dysrhythmias Myocardial ischemia.
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