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PubMed1997

Comparison between dobutamine echocardiography and thallium-201 scintigraphy in detecting residual stenosis, ischemia, and necrosis in patients with prior myocardial infarction.

BACKGROUND: Following the first attempts to detect myocardial ischemia with two-dimensional echocardiography stress testing, pharmacologic stress using dobutamine infusion has become an alternative to echocardiography exercise testing for evaluation of coronary artery disease. It has been shown that stress echocardiography has a diagnostic accuracy similar to that of an exercise thallium test. Other studies, however, indicated that radionuclide myocardial perfusion imaging was more sensitive than exercise or pharmacologic stress echocardiography for detection of ischemia or jeopardized myocardium. HYPOTHESIS: The aim of the present study was to determine the ability of dobutamine stress echocardiography in comparison with thallium-201 scintigraphy to identify multivessel disease and the presence of myocardial scar and ischemia in 60 consecutive patients who suffered a first myocardial infarction (MI). METHODS: Patients were evaluated by coronary angiography and ventriculography, thallium-201 (201TI) tomographic scintigraphy, and dobutamine echocardiography within 3 months of a first MI. Forty-seven had Q-wave MI and 13 had non-Q-wave MI. Eleven patients were excluded from final analysis-7 because of failure to achieve target heart rate in spite of the use of atropine, and 4 because of high blood pressure following the infusion of dobutamine. RESULTS: Dobutamine echocardiography showed an overall sensitivity of 43% for detection of coronary artery lesions of 50-74% diameter stenosis and 201TI scintigraphy showed a sensitivity of 71%. For detection of lesions of > or = 75% diameter stenosis, dobutamine echocardiography showed a sensitivity of 52% and 201TI a sensitivity of 70%. Overall agreement between wall motion and myocardial perfusion for detection of necrosis and/or ischemia in the infarct area was 40.4% with a kappa coefficient of 0.09 (p = 0.13). For detection of ischemic myocardium outside the infarct zone, overall agreement was 78.6% with a kappa coefficient of 0.49 (p < 0.0001). CONCLUSION: Dobutamine echocardiography results showed a lower sensitivity than myocardial perfusion images in predicting multivessel coronary artery disease, and there was poor agreement between both methods in identifying necrosis or ischemia.

Coronary Angiography↗
PubMedDate not supplied

Scintigraphic localization of ectopic parathyroid lesions with thallium-201.

Six consecutive patients with ectopic parathyroid lesions were studied by preoperative thallium-technetium scintigraphy. Ectopic lesions were accurately localized in 5 of 6 patients. Four of five lesions deep in the superior mediastinum, and 1 in the superior carotid sheath, were correctly identified. Ectopic lesions in 4 of 5 patients, who had previously undergone unsuccessful exploration, were correctly localized. In 1 previously unoperated patient, a mediastinal lesion was identified by preoperative scintigraphy. In 2 patients, deep mediastinal exploration via manubriotomy was successfully conducted without confirmation by "invasive" intravascular procedures. There were no false-positive studies. Lesions identified weighed from 185 mg to 9 g and were from 1.1 to 3.0 cm in size. Scintigraphy is particularly effective for demonstration of ectopic parathyroid tissue, because the absence of thyroid tissue in the mediastinum or superior cervical region permits appreciation of areas of abnormal thallium uptake unobscured by uptake in adjacent thyroid tissue. We conclude that ectopic parathyroid tissue may be accurately identified by thallium-technetium scintigraphy without confirmation by invasive intravascular studies.

Adult↗
PubMed1978

Some effects of a thallium salt on the proliferation of hair follicle cells.

Thallium sulphate has been given to young rats at 4 and 7 days of age and the mitotic activity of the hair follicles has been assessed quantitatively. It has been found that there is a marked decline in mitotic rate over 48 hr in the thallium-treated animals, which is followed by variable amounts of cell death in the matrix zone. No specific mitotic lesion was found or change in cell cycle indices. A failure of energy metabolism is suggested as a possible cause of the inhibition of hair follicle mitosis by thallium.

Animals↗
PubMed1984

Intestinal absorption and excretion of thallium (201Tl) in the rat.

The gastrointestinal transport of 201Tl-labelled monovalent thallium has been studied in normal and rats with cannulated bile ducts using an in vivo ligated loop technique. A marked difference in the Tl absorptive capacity among the various sections of the gut was observed. 201Tl was taken up more quickly from the colon than from any other segment and the uptake from the ileum and jejunum was higher than from the stomach. In addition, considerable amounts of the intravenously administered thallium were excreted into the intestinal lumen. The biliary excretion was very low compared with the direct transfer of 201Tl across the gastrointestinal wall that occurred against a tissue-to-plasma concentration gradient. In the rat, the large intestine seems to be the major area for the enteral reabsorption and recycling of thallium (I) ions.

Animals↗
PubMed1992

A comparison of maximal exercise and dipyridamole thallium-201 planar gated scintigraphy.

Both symptom-limited maximal exercise and intravenously given dipyridamole stress (0.56 mg/kg over 4 min with a 2 min walk) gated thallium scans were performed in 22 patients undergoing coronary arteriography for the assessment of chest pain. All scans were acquired gated to the electrocardiogram in 3 projections and were reported for the presence and extent of defects in 5 myocardial segments in each view. In addition, left and right ventricular myocardial uptake and estimates of right and left lung and liver to left ventricular uptake were assessed relative to the injected dose of thallium-201. Overall, 190/310 segments were abnormal with exercise compared with 169/310 with dipyridamole. Segments were scored greater in extent in 90/310 cases with exercise, compared with 46/310 in which the defect was more extensive with dipyridamole (P less than 0.0005). Non-attenuation corrected percentage myocardial thallium uptakes were similar for both stresses: anterior percentage uptakes, 0.785% +/- 0.230% with exercise versus 0.870% +/- 0.217% with dipyridamole (NSD). Left and right lung and liver to left ventricle ratios were all significantly higher with dipyridamole than with exercise (1.587 +/- 0.408 versus 1.446 +/- 0.518, P less than 0.02; 1.78 +/- 0.479 versus 1.46 +/- 0.502, P less than 0.002; 2.598 +/- 0.788 versus 1.265 +/- 0.386, P less than 0.001, respectively). High right and left lung uptakes with dipyridamole were strongly correlated with high exercise values (r = 0.756, P less than 0.001; r = 0.809, P less than 0.001). The liver uptake was weakly correlated between the 2 different stress tests (r = 0.483, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Serial assessment of denervated but viable myocardium following acute myocardial infarction in dogs using iodine-123 metaiodobenzylguanidine and thallium-201 chloride myocardial single photon emission tomography.

Iodine-123 metaiodobenzylguanidine (mIBG) is taken up by sympathetic nerve endings, allowing scintigraphic imaging of myocardial sympathetic innervation. We investigated the denervated but viable canine myocardium after acute myocardial infarction by serial mIBG and thallium-201 chloride (201TlCl) single photon emission tomography (SPET). In 12 dogs, acute myocardial infarction was produced by ligation of the left circumflex coronary artery. Images of mIBG and thallium SPET were obtained 6 h, 1, 4 and 6 weeks later. The defect size was calculated in percentage points from short axial views, and the 123I-mIBG/201TlCl ratio was determined. The uptake ratio was high at 1 week but gradually decreased. Three dogs were killed at each time point, and tissue samples were obtained from infarcted (both 201TlCl and 123I-mIBG defects), peri-infarcted (123I-mIBG defect and 201TlCl normal) and normal myocardium (both mIBG and 201TlCl normal). The changes in tissue content of noradrenaline in these lesions were measured. Noradrenaline tissue content gradually recovered in the peri-infarcted area. However, no recovery was noted in the infarcted area at 6 weeks. We conclude that sympathetic denervation and re-innervation occur following acute myocardial infarction, and the denervated but viable myocardium could be detected non-invasively by combined mIBG and thallium SPET.

3-Iodobenzylguanidine↗
PubMed1992

Efficiency of labelling of red blood cells with technetium-99m after dipyridamole infusion for thallium-201 stress testing.

Experimental studies have suggested that dipyridamole may inhibit red blood cell labelling with technetium-99m. To evaluate whether this effect is clinically relevant to the performance of radionuclide ventriculography after dipyridamole-thallium stress testing, in vitro red blood cell labelling was compared immediately before and after thallium-201 stress scintigraphy combined with either dipyridamole infusion (30 patients) or exercise stress (20 patients). Modified in vivo red blood cell labelling efficiency was assessed in a further 36 patients following dipyridamole infusion and was compared with that in 15 patients following exercise stress. The importance of a reversal of the dipyridamole effects by aminophylline was evaluated for in vitro and modified in vivo techniques. The red blood cell labelling efficiency was not significantly different in patients following dipyridamole compared with that obtained following exercise stress for both in vitro (93% +/- 4% versus 91% +/- 4%) and modified in vivo (87% +/- 19% versus 90% +/- 6%) techniques. Also, in vitro red blood cell labelling efficiency after dipyridamole was not different to that before stress testing (93% +/- 4% versus 92% +/- 4%). Reversal with aminophylline had no significant effect on the in vitro labelling efficiency with either the in vitro technique (94% +/- 3% with reversal versus 92% +/- 5% without) or the modified in vivo technique (91% +/- 4% with reversal versus 82% +/- 26% without). These results suggest that the red blood cell labelling efficiency is not compromised by the preceding dipyridamole-thallium stress testing but can be optimised by using in vitro labelling.

Aged↗
PubMed1985

An evaluation of the efficacy of charcoal haemoperfusion in the treatment of three cases of acute thallium poisoning.

The efficacy of intermittent charcoal haemoperfusion in combination with forced diuresis and Prussian blue therapy was evaluated in three cases of thallium poisoning. At a blood flow of 300 ml/min the average blood clearance values obtained with haemoperfusion were 72 +/- 11 ml/min (mean +/- SD) at a starting blood concentration above 2 mg/l and 120 +/- 23 ml/min (mean +/- SD) below this blood level. As a result of the combined intensive treatment, the thallium half-lives in blood observed during the period monitored were only 25-41 h. Removal of thallium by haemoperfusion is faster per unit of time than simultaneous excretion by forced diuresis. When forced diuresis was combined with intermittent (4-20 h intervals) haemoperfusion therapy, the total elimination by each technique was about equivalent over the period of combined treatment. Saturation of the Adsorba 300 C columns occurred during treatment. As a result, the clearance obtained did decrease to half the initial value in 2-3 h. As this decrease in efficacy is related to the blood concentration, haemoperfusion is more efficient at lower blood concentrations. This is in contradistinction to forced diuresis, of which the excretion is proportional to the blood concentration.

Acute Disease↗
PubMed1977

[Control of the intensive treatment of thallium intoxications (author's transl)].

A report is given on the control of the thallium level at poisoning during therapy with forced diuresis and extracorporeal hemodialysis. The success of these methods was controlled ty the determination of the thallium level in vomit, blood, urine and dialysate by flameless atomic absorption spectrophotometry. Since the results are obtained within a few minutes, thallium measurements may be helpful for the decision on the therapy to be applied.

Adolescent↗
PubMed1984

The action of thallium acetate on neuromuscular transmission in the rat phrenic nerve-diaphragm preparation.

In the isolated phrenic nerve-hemidiaphragm preparation from the rat, thallium acetate induced a dose-dependent irreversible paralysis. There was a major time lag between the onset of the exposure and the decline in the indirectly elicited muscle twitches. The slope of the decline was in proportion to the applied concentration, which ranged from 1 X 10(-3) to 5 X 10(-6) mol/l. The paralysis was definitively manifest after approximately 40 min of incubation. In the phase of paralysis, both electrical stimulation of the muscle and chemical stimulation by addition of K+ were fully effective. However, addition of 4-aminopyridine and/or guanidine restored the indirect muscle twitches, indicating a previous reduction of synaptic activity by thallium. Lowering the Ca2+-concentration resulted in a reduced paralysis time. From these results it is suggested that thallium interferes with synaptic transmission by presynaptically antagonizing Ca2+-dependent processes.

4-Aminopyridine↗
PubMed1984

The action of thallium acetate on spontaneous transmitter release in the rat neuromuscular junction.

Frequencies and amplitudes of miniature endplate potentials (MEPP's) were recorded from neuromuscular junctions of the rat phrenic nerve-diaphragm preparation in vitro. Superfusion of the preparations with Ringer solution containing thallium acetate (Tlac) gradually increased the frequency of MEPP's by a factor of 10 within 30 min (1 X 10(-3) mol/l Tlac) and 180 min (5 X 10(-4) mol/l Tlac), whereas the amplitude of MEPP's remained unchanged. Frequency of MEPP's fitted a Poisson-distribution which persisted during superfusion with Tl+-Ringer. Sub-MEPP amplitudes remained unaffected by the action of thallium. It is concluded that thallium interferes presynaptically with spontaneous transmitter release.

Action Potentials↗
PubMed1975

A rapid and specific method for the determination of traces of thallium directly in urine by differential pulse anodic stripping voltammetry.

The applicability of differential pulse anodic stripping voltammetry to the direct qualitative and quantitative analysis of thallium in urine has been investigated. Comparisons were made between the hanging mercury drop electrode and the mercury plated wax impregnated graphite electrode. The latter electrode was found to be somewhat more sensitive, with detection limits in the lower ppb range. For quantitative determination, the hanging mercury drop electrode showed better reproducibility. The effects of toxicologically important metals on the analysis of thallium were investigated and their possible interference could be eliminated by a proper choice of operating conditions. The advantages of the proposed method are its sensitivity, speed and low cost in comparison with other methods for detecting and measuring thallium.

Electrodes↗
PubMed1980

Salivary levels of thallium in acute human poisoning.

Thallium intoxication in a 28-year-old woman was characterized by neurological and gastrointestinal symptoms and alopecia. Treatment was started 4 days after poisoning and consisted of forced diuresis and administration of Prussian Blue at four daily doses of 5 g by duodenal tube for 20 days. Thallium was measured by atomic absorption spectrophotometry in urine, faeces and saliva. Considerable amounts of thallium were detected in saliva, salivary concentrations being up to 15 times higher than urinary ones. Evidence was also obtained that only a little fraction of the ingested dose was excreted by the intestine during the hospital course in spite of Prussian Blue administration.

Acute Disease↗
PubMed1990

Exercise thallium scintigraphy in aortitis syndrome (Takayasu's arteritis).

It is important for patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into four groups according to the angiographic findings. There were: five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In group A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Group C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy for detection of myocardial ischemia were 9/9 and 12/12, while those of stress ECG were 9/9 and 7/12 (58%), respectively. It is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.

Adult↗
PubMed1996

Technetium-99m tetrofosmin imaging in thyroid diseases: comparison with Tc-99m-pertechnetate, thallium-201 and Tc-99m-methoxyisobutylisonitrile scans.

Technetium-99m tetrofosmin is a lipophilic phosphine used for myocardial perfusion imaging. Biodistribution studies have shown significant thyroid uptake of tetrofosmin and preliminary reports have suggested that tetrofosmin imaging may be of value in patients with thyroid cancer. In this study, tetrofosmin whole-body scintigraphy was performed in 35 patients with evidence of thyroid diseases. All patients underwent laboratory evaluation of thyroid function as well as 99mTc pertechnetate scan, thallium-201 (n=16) 99mTc-methoxyisobutylisonitrile (MIBI) (n=19) whole-body studies. Thyroid images were semi-quantitatively analysed by a 4-point score: 0=no significant uptake; 1=uptake increased as compared to background activity, but inferior to normal thyroid tissue; 2=uptake equal to normal thyroid tissue; 3=uptake superior to normal thyroid tissue. Pathology examinations were obtained. A total of 41 thyroid nodules were detected, of which 15 were goitre nodules, 13 adenomas and 13 malignant lesions. In goitre nodules, concordant results of tetrofosmin and pertechnetate uptake (score 1 or 0) were observed in the majority of lesions (87%). In function adenomas (n=10), both tetrofosmin uptake and pertechnetate uptake were score 3. In non-function adenomas (n=3), tetrofosmin uptake was score 3, while pertechnetate uptake was score 0. In six malignant lesions, tetrofosmin uptake was score 3, while pertechnetate uptake was score 0; in the other seven lesions, where a prevalence of goitre abnormalities was observed, results of tetrofosmin and pertechnetate uptake were similar (score 0 or 1). In seven (70%) of the ten patients with malignant nodules, whole-body tetrofosmin images showed increased abnormal uptake in a total of 28 extra-thyroid tumour sites, as subsequently confirmed by other techniques. When tetrofosmin images were compared to 201Tl and 99mTc-MIBI scans, concordant results were observed in all cases. In conclusion, tetrofosmin imaging may be particularly useful to characterize and stage patients with malignant thyroid nodules; it shows similar results to thallium but provides better image quality. Comparable findings were observed between tetrofosmin and MIBI studies. Thus, tetrofosmin may be an alternative to thallium and MIBI in the aforementioned patients.

Adenoma↗
PubMed1992

Coronary arterial involvement in aortitis syndrome: assessment by exercise thallium scintigraphy.

It is important in patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty-one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into 4 groups according to the angiographic findings. There were five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In groups A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Groups C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy for detection of myocardial ischemia were 9/9 and 12/12, while those of stress ECG were 9/9 and 7/12 (58%), respectively. it is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.

Adult↗
PubMed1984

[Structure of the hair in thallium poisoning].

The alterations in the hair roots discovered by Widy in 1956 were interpreted as accumulations of pigment which form as a consequence of a catalytic action of the poison. The goal of the present investigation was to clarify the structure of these inclusions. Hair from the heads of six victims who were involved in the poisoning of Würzburg medical students in January 1983 was available as investigation material. In the investigation in transmitted light and in polarized light, the black zones typical for thallium intoxication were found filling to varying extents the root and hair shaft near the root. Their intensity corresponded to the degree of severity of the intoxication. When examined under reflected light, the inclusions were shown up with a white color. They thus showed the same optical behavior as the air-filled medullary strand of normal hairs. This indicates that gaseous constituents are involved. This hypothesis could be confirmed by further investigations. After mechanical damage to the hair (pressing under high pressure), the gaseous inclusions disappeared and with them the "thallium strip." The same effect was attained by the chemical action of various acids, embedding agents, and dye solutions. This process was especially rapid after exposure to thioglycolic acid; the escape of the gas bubbles can be directly observed here. Scanning electron microscopic investigations on transverse sections of hair revealed a loosening of the spindle-shaped elements of the fiber layer as signs of structural disturbance. The gaseous constituents in thallium hair arise as the result of a trophic disorder in keratin formation. The structural alteration due to this leads to alopecia.

Adult↗
PubMed1979

Noninvasive perfusion control by thallium-201 myocardial scintigraphy after coronary artery bypass surgery.

Thallium-201 myocardial scintigraphy, which has been shown accurate in the assessment of myocardial perfusion, was employed in the evaluation of 34 patients after coronary artery bypass surgery. In 28 patients (82.4%), there was a clear correspondence in the postoperative studies between the defects shown on scintigraphy and the coronary artery stenosis documented by arteriography. Thallium imaging after coronary artery bypass revealed an increased or newly developed scintigraphic defect in eight of 10 patients with recurrent angina. Follow-up arteriography in these 10 patients revealed occlusion or stenosis of the bypass graft in five, perioperative myocardial infarction in two, and increased stenosis of a preoperatively less occluded artery in two. In 24 patients with postoperative clinical improvement or relief of angina, 201Tl scintigraphy revealed complete normalization of thallium uptake in three, improvement of uptake in 17, and unchanged uptake defects in four.

Adult↗