thallium 201


Also found in: Dictionary, Thesaurus, Encyclopedia.

thallium

 [thal´e-um]
a chemical element, atomic number 81, atomic weight 204.37, symbol Tl. (See Appendix 6.) Its salts are active poisons that may cause alopecia, liver and kidney damage, blindness, and neurologic and psychic symptoms such as ataxia, restlessness, delirium, hallucinations, delusions, and semicoma.
thallium 201 a radioactive isotope of thallium having a half-life of 3.05 days and decaying by electron capture with emission of gamma rays. It is used as a diagnostic aid in the form of thallous chloride Tl 201.
thallium scan a scintiscan involving the use of thallium 201. The radioisotope is administered intravenously and localizes, like calcium, in the myocardium. A scintillation camera produces an image of the distribution of the radioisotope. Areas of inadequate perfusion appear as “cold spots,” thus pinpointing the site of occlusions of the coronary arteries.



The thallium scan offers many advantages. It is noninvasive except for the administration of the radioisotope, which involves a radiation dose slightly larger than that received during a chest x-ray, and is extremely accurate.

The thallium-201 may be administered while the patient is exercising on a treadmill and being monitored by electrocardiogram. Subsequent scintigrams show areas of inadequate perfusion. This test is less likely than conventional exercise or stress testing to indicate disease when none is present and is more likely to detect disease when it is present. See also exercise thallium scintigraphy and myocardial perfusion scintigraphy.

thal·li·um 201 (201Tl),

the radioisotope of thallium used widely for myocardial nuclear imaging; it is also taken up by certain tumors.

thal·li·um 201

(201TI) (thalē-ŭm)
Radioisotope of thallium used widely for myocardial nuclear imaging; it is also taken up by certain tumors.

thallium 201

A radionuclide used to diagnose ischemic heart disease. When injected at the peak of exercise during a graded exercise tolerance test, it circulates to the myocardium. Images of the heart can then be obtained to aid in the diagnosis of impaired coronary blood flow or prior myocardial infarction. See: exercise tolerance test; redistribution
See also: thallium
References in periodicals archive ?
The IAEA developed eight quality metrics for responsible radiation use in nuclear cardiology: avoiding thallium 201 stress testing, avoiding dual isotope testing, avoiding too much technetium-99m and thallium 201, using stress only imaging, use of camera technologies to reduce dose, use of weight based dosing strategies for technetium-99m, and avoiding inappropriate dosing that can lead to shine-through artefacts.
Determining myocardial viability in chronic ischemic left ventricular dysfunction: a prospective comparison of rest-redistribution thallium 201 single-photon emission computed tomography, nitroglycerin-dobutamine echocardiography, and intracoronary myocardial contrast echocardiography.
Thallium 201 chloride uptake in tumors a possible complication in heart scintigraphy.