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PubMed1992

Significance of increased Tl-201 uptake by the lungs in patients undergoing oral dipyridamole-thallium myocardial imaging.

The purpose of this study was to evaluate the significance of increased Tl-201 uptake by the lungs after oral dipyridamole testing. In conjunction with myocardial perfusion scintigraphy, intravenous dipyridamole has been recently approved as an alternative to exercise for the evaluation of coronary artery disease in patients who cannot adequately exercise, and it will largely replace oral dipyridamole testing. This study contributes to the understanding of the significance of increased lung thallium uptake during pharmacologic stress testing. Oral dipyridamole, 400 mg, was administered to 192 patients undergoing Tl-201 imaging for clinical indications. Mild adverse effects occurred in 31% of patients (chest pain, nausea, headache, or flushing). Dipyridamole had minimal hemodynamic effects. The lung/heart thallium activity ratio was determined in 152 patients. These were subdivided into four groups according to the presence or absence of ischemia, transient myocardial perfusion defect, or scar as indicated by a fixed myocardial perfusion defect. In 61 patients without transient myocardial perfusion defect or fixed myocardial perfusion defect (group 1), the lung/heart thallium activity ratio was 0.39 +/- 0.01 (mean +/- SEM). In 31 patients without transient myocardial perfusion defect but with fixed myocardial perfusion defect (group 2), the lung/heart thallium activity ratio was higher, 0.44 +/- 0.02 (P less than 0.05). In 27 patients with transient myocardial perfusion defect but no fixed myocardial perfusion defect (group 3) and in 33 patients with both transient myocardial perfusion defect and fixed myocardial perfusion defect (group 4), the lung/heart thallium activity ratio was 0.51 +/- 0.03 and 0.52 +/- 0.03, respectively, both significantly higher than either group 1 or group 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1994

Identification of reversible ischaemia after acute myocardial infarction using thallium tomography with early and delayed imaging after resting injection.

We studied 30 patients 6 weeks after first myocardial infarction in order to compare early and delayed imaging after resting injection of thallium for the detection of viable myocardium. Twenty-six of the 30 patients studied had received thrombolysis. Conventional stress and redistribution thallium tomography was followed by a resting injection of thallium with imaging immediately after in all patients and 3 h later in a subgroup of 15 patients. Thallium uptake was graded semi-quantitatively in each of nine myocardial segments. Eighty-eight of the 270 segments had a fixed defect on redistribution imaging, 40 (45%) of which had improved uptake in the immediate reinjection images. Only 9 of 135 (6%) segments with fixed defects on immediate reinjection imaging showed additional uptake with delayed reinjection imaging. These data suggest that imaging early after thallium reinjection is of value in the detection of reversible ischaemia after infarction, but that delayed reinjection imaging offers little additional benefit.

Exercise Test↗
PubMed1992

Thallium poisoning: an outbreak in Florida, 1988.

In October 1988, five of seven members of a Florida family were poisoned with thallium, constituting the largest outbreak of acute thallium poisoning in the United States since thallium was banned as a rodenticide in 1972. Three patients had an acute severe neuropathy with respiratory depression; one died. The other two had no symptoms. No cases were identified among nonhousehold relatives or friends, or in the community. Of the more than 100 environmental specimens collected at the family household and tested by atomic spectroscopy, three empty and four unopened glass soft drink bottles of the same lot number yielded thallium in a concentration fatal to humans. All family members who consumed the soft drink were poisoned (5/5) as compared with none of those who did not (0/2). Because poisoning was clustered to the family and police investigators provided evidence that the poisoning was deliberately targeted to the family, it was assumed that no other soft drink bottles contained thallium, and it was decided not to recall all soft drink bottles with the same lot number. A year later a neighbor of the family was arrested and convicted of the murder.

Adolescent↗
PubMed1990

Ineffectiveness of dipyridamole SPECT thallium imaging as a screening technique for coronary artery disease in patients with end-stage renal failure.

The efficacy of dipyridamole single photon emission computed tomography (SPECT) thallium as a screening test for coronary artery disease (CAD), was studied in 45 patients with end-stage renal failure undergoing evaluation for renal transplantation. Coronary arteriography, dipyridamole SPECT thallium imaging and clinical follow-up were performed in all patients. Nineteen patients (42%) had an obstruction of 50% or more in at least one coronary artery. Fourteen patients had a positive thallium scan, but 7 of these were false-positives (sensitivity 37%, specificity 73%). The sensitivity was considerably lower than that quoted for non-ESRF patients in the literature, and significantly lower than a control group of 19 patients without ESRF having comparable severity and distribution of CAD. Five of the 6 patients who died of cardiac causes over a mean follow-up period of 25 months had normal thallium imaging, but all had significant coronary artery disease at cardiac catheterization. Dipyridamole SPECT thallium imaging has not proved a useful screening test for angiographically significant CAD, and does not predict cardiac prognosis in this population.

Adult↗
PubMed1978

Thallium intoxication treated with long-term hemodialysis, forced diuresis and Prussian blue.

A 56-year-old woman, who ingested 2 g of thallium sulfate, was successfully treated with long-term hemodialysis for 200 hours during ten days, combined with forced diuresis and Prussian blue. The effect of the artificial kidney dialysis was determined by repeated analysis of the thallium concentration in the dialysis bath and in blood samples. During the first 120 hours of hemodialysis, 143 mg of thallium was eliminated via the artificial kidney and 110 mg via the urinary tract. The present case of acute thallium intoxication is the first in which long-term hemodialysis has been used in the acute phase together with forced diuresis and Prussian blue. The data obtained are compared to those obtained from cases treated with hemodialysis in the past. It is concluded that treatment with hemodialysis should be considered as an important supplement to treatment with forced diuresis and Prussian blue in cases of thallium intoxication.

Antidotes↗
PubMed1997

Effects of thallium ion on cellular components of the skin.

Thallium salts have been employed by dermatologists to cause depilation, and dermatologic features are prominent in thallium overdose. These features include alopecia and follicular hyperkeratosis. Administration of thallium to pregnant animals results in limb deformities, similar to those seen after thalidomide embryopathy. These findings suggest that thallium may act on keratinocytes, melanocytes, and endothelial cells. We show that thallium exerts pleiotropic effects on proliferation, cell shape and motility of multiple cell types. These findings may help explain the clinical findings of thallotoxicosis.

Animals↗
PubMed1997

Comparison of thallium-201 and gallium-67 scintigraphy in soft tissue and bone marrow multiple myeloma: a case report.

A 68-year-old female was referred for assessment of multiple myeloma. A large myelomatous infiltrate involving the left triceps muscle showed avid uptake on both thallium-201 and gallium-67 scintigraphy. Following radiotherapy, imaging with both radiopharmaceuticals showed resolution of disease; however, tumour recurrence in the bone marrow was seen only on thallium-201 imaging. This observation suggests that while soft-tissue myeloma shows similar appearances on thallium-201 and gallium-67 scintigraphy, both at baseline and following therapy, gallium-67 may not demonstrate bone marrow infiltration which is visualized on thallium-201 imaging. Therefore, thallium-201 appears to be superior to gallium-67 in evaluation of patients with multiple myeloma when soft tissues and bone marrow are involved.

Aged↗
PubMed1992

Early exercise thallium-201 single photon emission computed tomography in unstable angina: a prospective study.

To evaluate the safety and diagnostic value of early symptom-limited exercise electrocardiography (ECG) and exercise thallium-201 single photon emission computed tomography (SPECT) in unstable angina (UA), 39 patients were studied prospectively soon after stabilization on medical treatment. No patient had a history of myocardial infarction (MI) or revascularization and patients with left bundle branch block were excluded. Exercise ECG and exercise thallium-201 SPECT were performed 8 +/- 4 days and 11 +/- 6 days respectively after admission to hospital. Seventeen out of 39 patients (44%) had positive exercise ECGs and 22 (56%) negative or inconclusive ones. Exercise thallium-201 SPECT was positive in 26 patients (67%) and negative in 13 patients (33%). Thirty-one patients underwent coronary arteriography and 24 of them proved to have significant coronary artery disease (CAD). The sensitivity, specificity and positive predictive value of exercise ECG in detecting CAD are 62%, 86%, and 94% respectively while the corresponding results are 96%, 100%, and 100% for exercise thallium-201 SPECT. Therefore, it is concluded that the early symptom-limited exercise test is safe in medically stabilized patients with UA. Early exercise thallium-201 SPECT is highly sensitive and predictive of the presence of significant CAD among patients in the early recovery phase of UA and can be used in selecting this group of patients for coronary angiography and other therapeutic strategies.

Adult↗
PubMed1999

Absence of thallium-201 brain uptake in progressive multifocal leukoencephalopathy in AIDS patients.

OBJECTIVE: To evaluate the presence of thallium-201 brain uptake determined by thallium-201 brain SPECT (Tl-201 SPECT) in patients with progressive multifocal leukoencephalopathy (PML) and AIDS. MATERIAL AND METHODS: Six AIDS patients with stereotactic biopsy diagnosis of PML were prospectively evaluated with Tl-201 SPECT, Magnetic Resonance Imaging (MRI), and proton magnetic resonance spectroscopy (1H-MRS). Tl-201 SPECT results were compared with 2 patients with AIDS and biopsy proven primary CNS lymphoma. RESULTS: In all patients with PML, Tl-201 SPECT studies showed lack of uptake while MRI demonstrated subcortical white matter focal brain lesions and 1H-MRS disclosed metabolic abnormalities. Intense thallium uptake (uptake ratios of 3.2 and 5.6) was demonstrated in the 2 patients with primary CNS lymphoma. CONCLUSIONS: The present study shows that PML lesions are not detectable on Tl-201 SPECT while MRI and 1H-MRS demonstrate abnormalities, and intense thallium-201 uptake may be detected in primary CNS lymphoma. These results suggest that Tl-201 SPECT is a method which, combined with other non-invasive techniques such as MRI and 1H-MRS, may help in the diagnostic approach of PML and to differentiate PML from other high proliferative brain lesions characterized by positive thallium uptake.

AIDS Dementia Complex↗
PubMed1986

Pharmacodynamic effect of dipyridamole on thallium-201 myocardial perfusion in progressive systemic sclerosis with diffuse scleroderma.

We evaluated the effect of dipyridamole on thallium-201 myocardial perfusion in 23 patients with progressive systemic sclerosis (PSS) with diffuse scleroderma. Thallium-201 single photon emission computed tomography (SPECT) was performed at rest and after coronary artery vasodilatation with intravenous dipyridamole (0.14 mg/kg/min for four minutes). The left myocardium was divided into nine segments; each segment was graded as 2.0, 1.5, 1.0, 0.5, 0 (zero represents no activity). Dipyridamole significantly improved resting thallium-201 myocardial perfusion: the mean (SD) number of segments with thallium defects decreased from 6.0 (2.1) at rest to 4.1 (2.5) after dipyridamole (p less than 0.0001); the mean (SD) score in segments with resting defects increased from 0.92 (0.24) at rest to 1.13 (0.38) after dipyridamole (p less than 0.0001); the mean (SD) global score per patient increased from 10.2 (1.8) at rest to 11.4 (2.1) after dipyridamole (p less than 0.02); the global score increased by at least 2.0 in 12 patients and worsened by at least 2.0 in three patients only (p = 0.05). The results of this acute study suggest that some drugs with potent vasodilator activity on small coronary arteries may be beneficial in the treatment of PSS patients with thallium-201 myocardial perfusion abnormalities.

Adult↗
PubMed1986

Detection of coronary artery disease by thallium scintigraphy in patients with valvar heart disease.

In patients with valvar heart disease detection of coronary artery disease by conventional non-invasive methods may be difficult. The usefulness of thallium-201 exercise scintigraphy for detecting coronary artery disease was evaluated in 16 patients with aortic stenosis, 17 with aortic regurgitation, nine with mitral stenosis, and six with mitral regurgitation who were investigated by coronary angiography. Only two of 21 patients with greater than or equal to 50% coronary artery obstruction had normal thallium images. Three patients without angiographic evidence of coronary artery stenoses had perfusion defects demonstrated by thallium scintigraphy. Only one patient with greater than or equal to 75% coronary stenosis had a normal thallium scan. Angina pectoris or ST segment depression evoked by exercise test were not useful in distinguishing patients with coronary artery disease from those with normal coronary vessels. These data suggest that thallium exercise scintigraphy may be a useful non-invasive test for detecting coronary artery disease in patients with valvar heart disease.

Aortic Valve Insufficiency↗
PubMed1998

Left ventricular long axis disturbances as predictors for thallium perfusion defects in patients with known peripheral vascular disease.

OBJECTIVE: To compare resting long axis echocardiography with adenosine thallium-201 emission tomography in detecting myocardial ischaemic abnormalities in patients before peripheral vascular surgery. DESIGN: A prospective and blinded preoperative examination of resting left ventricular minor and long axes and myocardial perfusion during adenosine vasodilatation using thallium-201 emission tomography. SETTING: A tertiary referral centre for cardiac and vascular disease equipped with invasive, non-invasive, and surgical facilities. SUBJECTS: 65 patients (40 men) with significant peripheral vascular disease, mean (SD) age 63 (10) years, and 21 control subjects of similar age. METHODS: Segments were classified as normal, with fixed or reversible defects according to thallium-201 myocardial perfusion tomography. Systolic long axis abnormalities were either reduced excursion and/or abnormal shortening after A2, and diastolic abnormalities either delayed onset of lengthening > 80 ms and/or reduced peak lengthening rate < 4.5 cm/s. Segmental perfusion defects were compared with the equivalent long axes; anteroseptal for septal, inferoseptal for posterior, and lateral for left side giving a total of 195 segments. RESULTS: Systolic long axis abnormalities predicted fixed thallium defects (sensitivity 86%, specificity 87%, positive predictive value 0.78, negative predictive value 0.93, p < 0.001), and diastolic abnormalities correlated with reversible perfusion defects (sensitivity 90%, specificity 85%, positive predictive value 0.72, negative predictive value 0.95, p < 0.001). Echocardiography characteristics of the true and false positive segments were not different in the site or the extent of abnormalities. CONCLUSION: Systolic long axis abnormalities predict fixed and diastolic reversible thallium perfusion defects in patients with peripheral vascular disease. Ventricular long axis may thus have a value as a screening test before peripheral vascular surgery as well as providing a means of monitoring myocardial perfusion. The high negative predictive values indicate that a negative long axis study makes significant perfusion abnormalities very unlikely in patients with high pretest probability of coronary artery disease.

Adenosine↗
PubMed1991

Pulmonary Kaposi sarcoma in patients with AIDS: scintigraphic diagnosis with sequential thallium and gallium scanning.

Pulmonary Kaposi sarcoma associated with acquired immunodeficiency syndrome (AIDS) is difficult to diagnose because the clinical presentations and radiographic findings are nonspecific. The authors report three proved cases of AIDS-associated pulmonary Kaposi sarcoma diagnosed with sequential thallium and gallium scans. These scans demonstrated abnormal increase of pulmonary thallium uptake, whereas the gallium uptake was negative. In the authors' experience and in reports in the radiology literature, infected areas of the chest are generally thallium-negative on the delayed (3-hour) scans but are gallium-avid, whereas lymphomas are both thallium- and gallium-avid. The authors conclude that sequential thallium and gallium scans can be used to help diagnose pulmonary Kaposi sarcoma and distinguish it from other common AIDS-associated chest complications such as lymphoma and infections.

Acquired Immunodeficiency Syndrome↗
PubMed1976

Thallium 201 myocardial imaging in patients with pulmonary hypertension.

The appearance of the right ventricular myocardium on thallium 201 myocardial perfusion images was evaluated in patients with chronic pulmonary hypertension and compared to patients without pulmonary hypertension. Four groups of patients were studied: 1) eight normals, 2) five patients with angiographically documented coronary artery disease and normal pulmonary artery pressures, 3) ten patients with moderate to severe pulmonary parenchymal or vascular disease and documented pulmonary hypertension and 4) eight patients with chronic left ventricular dysfunction and pulmonary hypertension discovered during cardiac catheterization. The right ventricular free wall was visualized on the thallium 201 myocardial perfusion image in only one of eight normals (group 1) and in only one of the five patients with coronary artery disease (group 2) and measured 0.5 cm and 0.9 cm in thickness, respectively. In patients with documented pulmonary hypertension the right ventricle was visualized on low contrast thallium 201 myocardial perfusion image in all patients. The apparent right ventricular free wall thickness measured from the ungated thallium 201 myocardial perfusion images was 1.7 +/- 0.3 cm in group 3 and 1.5 +/- 0.2 cm in group 4. Right ventricular hypertrophy was detected by electrocardiography in only five of ten patients in group 3 and only one of eight patients in group 4. Thallium 201 myocardial perfusion imaging appears to be a useful technique for assessing the effects of chronic pulmonary hypertension on the right ventricular myocardium.

Chronic Disease↗
PubMed1978

Thallium-201 scintigraphy in unstable angina pectoris.

Thallium-201 scintigraphy was performed during the pain free period in 98 patients with unstable angina. Scintiscans were positive in 39 patients, questionable in 27 patients and normal in 32 patients. Eighty-one patients responded favorably to treatment (group I). Seventeen patients had complicated courses (group II) and despite maximal treatment with propranolol either developed infarction (six patients) or continued to have angina necessitating coronary surgery (11 patients). In group I during the pain free period 26 of 81 patients had positive thallium-201 scans, whereas 20 patients had an abnormal ECG at that time; during angina 18 patients had transient ECG changes. In group II during the pain free period 13 of 17 patients had positive scans, whereas two patients had abnormal ECG at that time; during angina 12 patients showed transient ECG changes. The sensitivity to recognize group II was 76% for thallium-201 scintigraphy, 11% for ECG during the pain free period; 70% for ECG during angina; 94% for the combination of either positive scans or abnormal ECG. Thus, 1) positive thallium-201 scans occur in patients with unstable angina, 2) positive scans can be obtained during the pain free period, 3) thallium-201 scans are more frequently positive in patients with complicated course.

Angina Pectoris↗
PubMed1979

Usefulness and limitations of thallium-201 myocardial scintigraphy in delineating location and size of prior myocardial infarction.

In order to evaluate the usefulness of thallium-201 (201TI) myocardial scintigraphy in delineating the location and size of prior myocardial infarction, 32 patients were evaluated at a mean of 7 +/- 2 months after infarction with a 12-lead ECG, resting 201TI myocardial scintigram, biplane left ventriculogram and coronary angiograms. From the left ventriculogram, asynergy was quantified as percent abnormally contracting segment (% ACS), the percent of end-diastolic circumference which was either akinetic or dyskinetic. Using a computerized planimetry system, we expressed 201TI perfusion defects as a percentage of total potential thallium uptake. Of 21 patients with ECG evidence of prior transmural infarction, a 201TI defect was present in 20 (95%), and angiographic asynergy was present in all 21 (100%). The site of prior infarction by ECG agreed with the 201TI defect location in 24 of 32 patients (75%) and with site of angiographic asynergy in 23 of 32 patients (72%). Scintigraphic defects were present in only four of 10 patients (40%) with ACS less than or equal to 6%, but scintigraphic defects were found in 20 to 22 patients (91%) with ACS greater than 6% (p less than 0.01). Thallium defect size correlated marginally with angiographic left ventricular ejection fraction (r = -0.60) but correlated closely with angiographic % ACS (r = 0.80). Thallium defect size was similar among patients with one-, two-, or three-vessel coronary artery disease (greater than or equal to 70% stenosis), but thallium defect size was larger in patients with electrocardiographic evidence of transmural infarction (p less than 0.01) or pulmonary capillary wedge pressure greater than 12 mm Hg (p less than 0.001). Thus, resting 201TI myocardial scingigraphy is useful in localizing and quantifying the extent of prior myocardial infarction, but is insensitive to small infarcts (ACS less than 6%).

Angiocardiography↗
PubMed1991

Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis.

BACKGROUND: This study tested the hypotheses in the setting of a coronary artery stenosis that 1) planar 99mTc-teboroxime myocardial scans are capable of providing a good estimate of relative coronary flow reserve, and 2) delayed washout of the tracer from the myocardium is a marker of reduced myocardial blood flow and, in certain cases, myocardial ischemia. METHODS AND RESULTS: Experiments were conducted in eight closed-chest domestic swine prepared with an artificial stenosis that reduced diameter of the left anterior descending coronary artery by 80%. Measurements of hemodynamics, regional myocardial blood flow, oxygen, and lactate metabolism were made 1) at baseline, 2) after 5 minutes of intravenous infusion of adenosine and neosynephrine ("stress"), and 3) at recovery 2 hours after discontinuing the adenosine/neosynephrine infusion. Simultaneous intravenous injection of teboroxime (approximately 9 mCi) and thallium (approximately 3.5 mCi) was made at peak stress, and serial planar teboroxime imaging began 1-2 minutes later. Scans were made in dynamic mode for 30 seconds each for 7 minutes after which a stress thallium scan (7 minutes acquisition) was obtained. A redistribution thallium scan was made 2 hours later after which a repeat teboroxime injection followed by serial imaging for 7 minutes was performed. The animal was then killed, and the heart removed for determination of microsphere activity. Under baseline conditions, transmural myocardial blood flow (ml/min/g) distal to the stenosis (1.06 +/- 0.17) was reduced (p less than 0.01) compared with the normally perfused circumflex zone (1.50 +/- 0.31). In response to intravenous infusion of adenosine/neosynephrine, flow increased (p less than 0.01) compared with baseline in both distal (2.00 +/- 0.84) and circumflex (4.67 +/- 1.55) zones. However, the distal : circumflex flow declined (0.45 +/- 0.17) compared with baseline (0.73 +/- 0.17; p less than 0.01). Two hours later flow had returned to baseline levels in both zones, and lactate production during stress (-41.7 +/- 37.5 mumol/min/100 g) had reverted to consumption (13.6 +/- 7.7; p less than 0.05). Analysis of stress teboroxime scans demonstrated 1) an increase (p less than 0.01) in the ischemic : normal zone (IZ:NZ) count between 30-second (0.50 +/- 0.14) and 7-minute scans (0.61 +/- 0.11); 2) a good correlation between the 30-second scan IZ:NZ count and the stress distal : circumflex flow (0.45 +/- 0.17; r = 0.74; p less than 0.05; slope = 0.90; intercept = 0); and 3) a close correlation between the IZ:NZ count of the 7-minute scan (0.61 +/- 0.11) and the recovery distal : circumflex flow (0.69 +/- 0.21; r = 0.89; p less than 0.01). The IZ:NZ count also increased (p less than 0.01) between 30-second (0.65 +/- 0.15) and 7-minute (0.72 +/- 0.14) scans following rest injection of teboroxime. As anticipated, serial thallium scans demonstrated evidence of redistribution between stress (IZ:NZ count = 0.62 +/- 0.08) and recovery (IZ:NZ count = 0.75 +/- 0.06; p less than 0.01) time points. The stress thallium scan IZ:NZ, however, was greater than that of the 30-second teboroxime scan as well as that of the stress distal : circumflex flow. CONCLUSIONS: Accordingly, the data indicate that 1) myocardial imaging with 99mTc-teboroxime is valuable in the noninvasive assessment of relative coronary flow reserve and that 2) delayed washout of the tracer from the myocardium reflects reduced myocardial blood flow and, under conditions comparable to those of the present study, may be a marker of myocardial ischemia.

Animals↗
PubMedDate not supplied

Thallium uptake by canine iliac arteries.

Most of the thallium uptake by canine iliac arteries (70%) was inhibited by ouabain. The component sensitive to ouabain was significantly increased by incubating tissues in K+-free solution and reduced by low temperatures, metabolic inhibitors, and loading with lithium. The apparent Km for thallium for the ouabain-sensitive uptake was 0.47 +/- 0.046 mM. External K+ inhibited thallium uptake and the apparent Ki was estimated to be 6.5 mM. Thallium thus appears to have a greater affinity for the ouabain-sensitive components. The residual component of thallium uptake was unaffected by maneuvers that affected the ouabain-sensitive uptake, which thus appears to be a suitable indicator of Na+ pump activity in vascular smooth muscle.

Animals↗