Thallium scan

Schelbert HR. Are the irreversible perfusion defects on myocardial thallium scans really irreversible Eur Heart J 1988 9 Suppl F 23-28... 

Thallium scanning with the aid of computer analysis segregates the images into anatomic regions and specifically localizes areas of dead or necrotic myocardial tissue. In conjunction with ECHO or SPECT, thallium scans can correlate areas of abnormal wall motion with areas of poor perfusion. Sensitivity and specificity of thallium scanning to detect IHD disease are comparable with those of ET (75% and 80%, respectively). When used in conjunction with exercise ECG, sensitivity increases to about 80%. Thallium scanning also can be used in conjunction with ET to allow detection of lower levels of ischemia than may be determined from ECG abnormalities or patient... 

Dobutamine, a synthetic catecholamine, increases heart rate and cardiac output, resulting in an increase in myocardial oxygen demand. Ischemia develops in areas where stenosis prevents the increase in oxygen demand from being met with increased blood flow. Ischemia is detected by ECHO as regional wall motion abnormalities or with thallium scanning. 

Digital subtraction angiography Dipyridamole-thallium scan Dobutamine stress test Doppler studies Echocardiography Electrocardiography Electrophysiologic study Fibrinogen... 

When the exercise test is being performed to evaluate concomitant ischemia, it will be necessary to use an ancillary method for evaluating the presence or absence of ischemia as the baseline ECG will be abnormal with a markedly abnormal ST-T wave. In the presence of both a pace rhythm from the RV apex as well as a spontaneous LBBB, there may be septal perfusion abnormalities detected by a thallium scan even in the absence of atherosclerotic coronary artery disease. The abnormal activation sequence will also cause an abnormal contraction pattern that may impair a stress-echo study. 

Although the rotational anisotropy scans are informative, considerably more information can be obtained by separate determination of changes in the isotropic and anisotropic components of the surface susceptibility tensor as done by Koos et al. [122]. The experiments consist of monitoring the SH intensity at a fixed angle of 0 = 30° where / oc a 2 and Tj a b0) 2. The results shown in Fig. 5.16 are displayed in terms of thallium coverage. The data has been fitted to a simple linear Langmuir isotherm model of Heinz [79] where the adsorbate contribution to x(2) varies linearly with coverage such that... 

Royalty-Free/Corbis. Reproduced by permission p. 209 Yen dell, Thomas, a Thalidomide baby, picks up a toy with his feet, photograph. AP/Wide World Photos. Reproduced by permission p. 215 Thallium heart scan, photograph by Peter Berndt, M.D. Custom Medical Stock Photo. Reproduced by permission p. 226 Thomson, Sir Joseph John, photograph. UPI/Corbis-Bettmann. 

Figure 7.20. Comparison of WDS (top, using LiF and thallium acid phthalate (TAP (1010), respectively) and EDS for the analysis of a superalloy. A number of X-ray spectral lines such as Ta La, Ni Kp, and W La are hardly discernible using EDS, but readily visible using WDS analysis. Reproduced with permission from Goldstein, J. Newbury, D. Joy, D. Lyman, C. Echlin, R Lifshin, E. Sawyer, L. Michael, J. Scanning Electron Microscopy and X-Ray Microanalysis, 3rd ed., Kluwer New York. Copyright 2003 Springer Science and Business Media.

A 34-year-old woman with acute promyelocytic leukemia was given arsenic trioxide solution 0.1%, 10 ml/day for 7 days. A generalized skin rash appeared, and her serum transaminases rose. An electrocardiogram was normal. A second course of arsenic trioxide was used about 3 months later. She felt palpitation and mUd dyspnea and had complete atrioventricular block. Echocardiography showed a normal left ventricle. A thallium myocardial perfusion scan did not show a perfusion defect. Arsenic trioxide was withheld. Sinus rhythm returned 3 days later. Complete atrioventricular block recurred later when arsenic trioxide was re-administered, albeit in a lower dosage for a shorter period of time. 

The principle of dipyridamole and adenosine thallium imaging is related to their coronary arteriolar vasodilator properties. Dipyridamole inhibits adenosine cellnlar renptake, resulting in increased concentrations of adenosine in the blood and tissues. Adenosine is a potent coronary artery vasodilator and can increase perfusion four to five times over baseline. Areas distal to a coronary artery obstruction will show a relative hypoperfnsion compared with normal coronary arteries because there is reduced perfusion pressure owing to preferential perfusion of normal segments over stenotic segments. Acutely, these areas will appear as cold spots, but on the redistribution scans, the defects will fill, indicating viable bnt jeopardized myocardium. 

The soft metal thallium is used in heart scans to evaluate the blood supply to the heart. 

The sample solution is aspirated into a toroidal shaped plasma, where atomization and excitation occurs. The emitted radiation is either measured simultaneously at previously selected atom lines, or one line after the other is sequentially scanned. The actual sensitivity depends on many parameters of the apparatus used, such as the type of nebulizer, optics, power, gas-flows, and observation height (for general review, see Broekaert and Tdig, 1987). If solvent extraction is applied as a technique for separation and preconcentration, however, it should be kept in mind that the plasma is easily distorted and extinguished by organic solvents. For thallium, there is some choice between different lines, but sensitivity is rather poor in any case, so that the direct application to decomposition solutions of rocks, soils, and biological samples is limited. 

Thallium-201 is a radioisotope used by medical professionals to determine the health of a persons heart. During a thallium-201 scan, also called a heart stress test, a patient performs physical activity and is injected with thallium-201 one to two minutes before stopping the activity. The isotope emits gamma rays that are recorded by a detector to display a two-dimensional image of the heart and its blood supply. If gamma rays are not detected in certain areas in and around the heart, the areas are considered cold. This means that the blood supply has been impeded or blocked, a condition that often leads to heart attack or stroke. 

The dark blue areas in this thallium-201 scan are areas with low blood supply. 

Summarize how "cold" areas in thallium-201 scans could correspond to artery blockages. 

The whole-body counter is equipped with six sodium iodide doped with thallium (Nal(Tl)) detectors, combined in two triangular arrays. The upper array consists of three detectors that scan above and the lower array of three detectors that scan below the subject. The upper array is on a moveable arm that can be raised from the bed surface to the roof of the counting chamber. The lower array is in a fixed geometry 12 cm below the bed. 

Fig. 17. Isotopic abundances of thallium recorded electrically by FDMS and signal accumulation in a multichannel analyzer. For each measurement SO cyclic magnetic scans are performed, a natural abundance of thallium, theor. m/z 203 = 29.5%, m/z 205 = 70.5% > found m/z 203 = 29.2%, m/z 205 = 70.S%, standard deviation 0.18, mean error = 0.08 b stable isotope-enriched internal standard, measurement certificate of the Russian manufacturer (supplied by RohstofTEinfuhr GmbH, Diisseldorf, FRG.) isotope T1 = 87.0%, isotope T1 = 13.0%, found m/z 203 = 87.7%, m/z 205 = 12.3%, standard deviation 0.46, mean error = 0.20 c quantitative determination of thallium traces in brain tissues. Found m/z 203 = 43.01 %, m/z 205 = 56.99%, standard deviation 1.28, mean error = 0.57...

Doctors examine the heart s pumping performance and check for evidence of obstruction in coronaiy arteries by -nuclear scanning. The radionuclide Tl-201, when injected into the bloodstream, lodges in healthy heart muscle. Thallium-201 emits gamma radiation, which is detected by a special imaging device called a scintillation camera. The data obtained are simultaneously translated into pictures by a computer. With... 

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