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PubMed1995

Relationship between reverse redistribution on planar thallium scintigraphy and regional myocardial viability: a correlative PET study.

UNLABELLED: The purpose of this study was to assess myocardial metabolic activity in the area of reverse redistribution and determine the prognostic value of reverse redistribution and PET imaging. Reverse redistribution is thought to be a manifestation of reperfusion therapy and associated with a favorable clinical outcome. Preliminary observations from the Thrombolysis and Myocardial Infarction (TIMI) trial suggest that reverse redistribution is associated with higher incidence of future cardiac events. METHODS: Thirty-two patients with chronic coronary artery disease and reverse redistribution on planar thallium scintigraphy had PET 13NH3/18FDG imaging. Radionuclide angiocardiography was performed in 23 patients. RESULTS: Fifty segments showed reverse redistribution on planar thallium images; 19 segments had normal 13NH3 and 18FDG uptake and 17 were ischemic by PET criteria. Thus, a total of 72% (36 of 50) of reverse redistribution segments were PET viable. Sixty-one percent of segments with abnormal regional wall motion and reverse redistribution were PET scar. On follow-up, 31% (10/32) had a cardiac event (nine unstable angina and one myocardial infarction). Fifty percent of patients (5/10) with cardiac events had severe reverse redistribution and PET viability versus 9% (2/22) without cardiac events (p = 0.01). CONCLUSIONS: The majority of thallium reverse redistribution segments was PET viable as judged by 18FDG uptake. Viability in areas of reverse redistribution is not inferred by regional wall motion analysis. Regional PET viability identifies patients with reverse redistribution with a higher likelihood of future cardiovascular events. PET viability assessment may be helpful with the impact of reverse redistribution on planar thallium scintigraphy.

Aged↗
PubMed1994

Myocardial distribution of retrograde cardioplegic solution assessed by myocardial thallium 201 uptake.

Perfusion of the right ventricular myocardium with retrograde infusion of cardioplegic solution through the coronary sinus has been reported to be less than optimal. To study left and right ventricular perfusion during retrograde and antegrade coronary sinus cardioplegia, we added 0.5 mCi of thallium 201 to 500 ml of hyperkaliemic crystalloid cardioplegic solution injected retrogradely into the coronary sinus at low perfusion pressure (20 to 40 mm Hg) in 14 dogs and antegradely in the ascending aorta in seven dogs. The cardioplegic solution was cold (4 degrees C) in eight animals perfused retrogradely and warm (21 degrees C) in 13 animals. After aortic crossclamping, the ascending aorta and the left and right ventricles were vented and cardioplegic solution was injected retrogradely into the coronary sinus. Antegrade injections were performed after aortic crossclamping and venting of the left and right ventricles and of the left and right atrium. After cardioplegic arrest, the heart was harvested, fixed, and scanned with a gamma camera. With cold retrograde cardioplegia, 82% +/- 5% of the injected thallium 201 activity was identified in the myocardium--71% +/- 9% for warm retrograde perfusion and 80% +/- 3% for antegrade perfusion (p > 0.05). Focal areas of hypoactivity in the septum and in the right ventricular free wall were present at scintigraphic imaging in all animals receiving retrograde perfusion. In conclusion, most thallium 201 activity of cardioplegic solution injected retrogradely in the coronary sinus was identified in the myocardium, but focal areas of hypoactivity in the septum and in the right ventricular free wall were present, indicating uneven distribution. Temperature of the crystalloid solution had no effect on the myocardial distribution of the thallium 201 radiotracer in the myocardium.

Animals↗
PubMed1994

Reproducibility of thallium-201 exercise SPECT studies.

UNLABELLED: A detailed analysis of intrapatient reproducibility of exercise SPECT thallium studies is presented. METHODS: Twenty patients in stable condition were re-examined with exercise-redistribution SPECT201 Tl within 3-9 days without intervening procedures. At peak stress, 3.5 mCi 201Tl were given intravenously 1 min prior to exercise termination. SPECT imaging started at 5 and 180 min. Acquisition and processing protocols were the same for all studies. Coronary angiography was performed on 19 patients and showed coronary artery disease (CAD) in 18, and no CAD in one; one patient did not have coronary arteriography. RESULTS: For 16 of 20 patients, exercise levels and ECG were comparable for both studies. Ten patients reproduced ST-segment depression; two reproduced angina; one had left bundle branch block (LBBB) on both studies after 1 min of exercise. The remaining seven patients had no ECG changes or symptoms during exercise. Four of 20 (20%) thallium scans differed: three in degree of redistribution and one (5%) in presence of a second stress defect. In three of four patients whose thallium studies showed some nonreproducibility, there were differences in exercise. Thallium results were identical in 15 of 16 patients whose ECG/exercise tests were reproducible (94%). Interobserver agreement was 95%. CONCLUSION: There was excellent reproducibility of 201Tl SPECT scintigraphy in patients who reproduced exercise test performance and symptoms.

Coronary Angiography↗
PubMed1994

Cardiac stress testing with thallium-201 imaging reveals silent ischemia in individuals with paraplegia.

The purpose of this study was to determine through noninvasive arm ergometry and radionuclide tomographic imaging the presence of latent coronary heart disease (CHD) in subjects with paraplegia. Assessment of CHD in spinal cord injury, using these methods, has not been addressed previously. Twenty asymptomatic subjects with paraplegia performed arm ergometry exercise stress testing with thallium-201 single photon emission computerized tomography (SPECT) or planar myocardial imaging studies. All subjects had normal resting electrocardiograms (ECG). Only five subjects had ECG evidence of ischemia on exercise testing, whereas 13 subjects, including the five subjects with ECG positive stress tests, had scintigraphic evidence of ischemia. Thus, eight subjects would have been undiagnosed for CHD without thallium-201 SPECT imaging. These individuals had multiple risk factors for CHD and, except for age, were without a statistically significant difference between the groups with positive or negative thallium stress imaging studies. Arm ergometry stress thallium imaging shows a high prevalence of ischemia in subjects with paraplegia.

Adult↗
PubMed1994

Improved detection of viable myocardium with thallium-201 reinjection in chronic coronary artery disease: comparison with technetium-99m-MIBI imaging.

Exercise-redistribution 201Tl with reinjection at rest and exercise-rest 99mTc-methoxy isobutyl isonitrile (MIBI) cardiac imaging was performed in a patient with multivessel chronic coronary artery disease (CAD) and evaluated before and after coronary revascularization. Thallium reinjection showed reversible defects of the inferior and septal walls and irreversible defect of the infero-apical region. Technetium-99m-MIBI scintigraphy demonstrated irreversible defects of the inferior, septal and infero-apical regions. After coronary artery bypass grafts, both thallium reinjection and 99mTc-MIBI images showed only irreversible defects of the infero-apical region. Functional recovery of the inferior and septal walls was observed on two-dimensional echocardiography. Thallium reinjection identifies severely ischemic but viable myocardium more accurately than 99mTc-MIBI in chronic CAD. Thallium myocardial imaging with reinjection at rest is recommended for evaluating patients with chronic ischemic left ventricular dysfunction to determine if these patients are candidates for revascularization procedures.

Coronary Artery Bypass↗
PubMedDate not supplied

[Fatty acid metabolic and perfusion abnormalities in hypertrophied myocardium assessed by dual tracer tomography using thallium-201 and iodine-123-beta-methylpentadecanoic acid].

Fatty acid metabolic and perfusion abnormalities associated with cardiac hypertrophy were investigated using dual tracer tomography with thallium and a cardiac metabolic tracer, 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (BMIPP), in eight patients with hypertrophic cardiomyopathy (HCM) and in three with hypertension (HT). Thallium and BMIPP uptakes were scored and analyzed in 143 segments (13/heart) by comparison with the left ventricular wall thickness measured by two-dimensional echocardiography. Complete agreement of both scores in HT patients was significantly higher than that in HCM patients (64% vs 24%, p < 0.001), while a lower BMIPP uptake compared to that of thallium (mismatching) was observed more frequently in HCM than in HT patients (65% vs 31%, p < 0.001). The wall thickness significantly (p < 0.005) correlated with BMIPP uptake score. HCM patients showed a low BMIPP uptake in 22 hypertrophic segments (59%) and 15 non-hypertrophic segments (41%), and reduced BMIPP uptake in 29% hypertrophic segments, while HT patients showed just five segments with decreased BMIPP uptake of which 4 were non-hypertrophic and only one hypertrophic. The left ventricular ejection fraction assessed by radionuclide ventriculography was normal and no regional wall motion abnormality was detected in any patient by echocardiographic and scintigraphic studies. Metabolic abnormalities detected by the iodine-123-beta-methyl fatty acid analog in hypertrophic cardiomyopathy may be independent of thallium myocardial perfusion, regional wall motion, or the magnitude of cardiac hypertrophy, suggesting that fatty acid imaging may be useful in investigating the pathogenesis and subclinical abnormality of hypertrophic cardiomyopathy, and differentiation from secondary, induced cardiac hypertrophy.

Adult↗
PubMed1993

[The echo-nitrate test for the detection of viable myocardium after a myocardial infarct: a comparison with delayed-acquisition thallium scintigraphy].

BACKGROUND: The aim of this study was to evaluate the ability of echocardiography, associated with nitroglycerin infusion, in the detection of myocardial viability in patients with recent infarction. PATIENTS AND METHODS: Fourteen patients (11 male, 3 female, mean age 59 +/- 8 years) with first acute myocardial infarction (12 Q wave, 2 non-Q wave) underwent predischarge (18 +/- 3 days) nitrate echocardiography. All patients underwent delayed planar thallium scintigraphy within four weeks from AMI. Nitrate echocardiography was performed with a nitroglycerin infusion starting from 0.4 mcg/Kg/min every 5 minutes up to 2.0 mcg/Kg/min; the test was terminated with an improvement of wall motion abnormalities or with a drop of systolic blood pressure > or = 20%. Wall motion abnormalities were evaluated with a 16-segment wall motion score index (WMSI). Thallium was performed after a symptom-limited exercise test, after 3 and 24 hours. The left ventricle was divided in 15 regions. Thallium was considered the gold standard for myocardial viability. RESULTS: Basal echo identified 59 dyssynergic segments: of these, 12 (20%-6 patients) showed improvement in contractility during nitrate echocardiography at a mean dose of 0.9 +/- 0.3 mcg/Kg/min. WMSI decreased from 1.42 +/- 0.22 to 1.27 +/- 0.13 (p = 0.022), with no significant change of haemodynamic data (mean systolic blood pressure from 125 to 112 mmHg; mean heart rate from 66 to 76 beats/min; mean rate/pressure product from 8415 to 8848; all p = ns). Thallium scintigraphy showed 40 fixed defects (19%-7 patients) and 10 (4.7%-7 patients) late reversible defects. 20% of the 3-hour fixed defects improved at 24-hour imaging. 5/7 patients with echo improvement had 24-hour reversible defects, while 6/7 with no WMSI improvement had 24-hour fixed defects. Therefore, nitrate echocardiography demonstrated 71% sensitivity, 86% specificity, 83% positive predictive value, 75% negative predictive value and 78% accuracy. CONCLUSIONS: Nitrate echocardiography may be a feasible and low cost method in the detection of myocardial viability after myocardial infarction, but awaits further validation.

Aged↗
PubMed1993

A complementary role for thallium-201 scintigraphy with mammography in the diagnosis of breast cancer.

Physical examination and mammography are currently the only proven and reliable methods of early detection of breast cancer. Although both procedures are highly sensitive, their limited specificity often requires surgical biopsy in order to differentiate between malignant and benign lesions. The purpose of this prospective study is to investigate the diagnostic specificity of thallium imaging for breast cancer and to determine its efficacy as a complement to mammography. Two groups were studied: Group A: Patients found to have breast abnormalities and scheduled for biopsy or surgery and Group B: Patients who were suspected to have a recurrence of cancer after mastectomies or lumpectomies. In Group A, thallium scans of 32 breasts in 30 patients were performed prior to biopsy or surgery, yielding pathological diagnoses of 31 breasts in 29 patients. Results for Group A included seven true-positive thallium scans, twenty-two true-negative scans, two false-negative scans, and one false-positive scan. In Group B, seven patients were scanned to evaluate subcutaneous nodules for breast cancer following mastectomy or lumpectomy. Results for Group B included five true-positive scans, one true-negative scan, one false-negative scan and no false-positive scans. Thallium breast scanning was shown to have high specificity for cancer (specificity 96% and sensitivity 80%), suggesting that this technique should be evaluated in additional patient studies to determine its role in clinical situations.

Adult↗
PubMed1993

[Yield of myocardial perfusion study with Thallium 201 in coronary artery disease: planar analysis].

The yield of exercise thallium-201 scintigram was studied in a group of 101 patients with suspected coronary artery disease or with a history of an old acute myocardial infarction. The thallium perfusion imaging was performed with planar technology and was interpreted visually. Its results were compared with conventional exercise testing and the results of a coronary arteriography performed within 30 days. Global sensitivity for conventional exercise testing was 60.4%, which increased to 78.2% with the thallium study. Specificity was raised from 47.2 to 84.8%. In patients with one, two or three vessel disease, thallium scintigram was abnormal in 95.1%, 96.6% and 100% respectively (NS).

Adult↗
PubMed1993

Rest/exercise thallium myocardial perfusion imaging: a new and rapid technique to evaluate coronary artery disease.

Twenty-six patients underwent conventional exercise/4-h redistribution thallium myocardial perfusion imaging as well as rest/exercise imaging on different days. For the rest/exercise study, patients were imaged 10 min after receiving 1 mCi thallium at rest. The resting study was immediately followed by symptom-limited treadmill exercise. Patients were injected with 2 mCi thallium at peak exercise and imaged 10 min later. The entire rest/exercise study was completed in 2 h. There was a high degree of correlation between the two studies. Of the 130 segments analysed, 84 were normal and 46 were abnormal by exercise/redistribution imaging whereas 88 were normal and 42 were abnormal by rest/exercise imaging. Among the 14 patients who had coronary arteriography, both exercise/redistribution and rest/exercise imaging correctly identified 23/35 segments as abnormal (sensitivity [pi003] 66%) and 34/35 segments as normal (specificity = 97%). Furthermore, abnormal segments were more likely to be reversible on the rest/exercise study. The results suggest that the accuracy of rest/exercise thallium imaging is equal to conventional exercise/redistribution imaging in the evaluation of coronary artery disease. The significant time economy and possible improvement in assessing myocardial viability are important potential advantages of this new technique.

Aged↗
PubMed1993

Value of thallium myocardial imaging in the prediction of future cardiovascular events in patients with end-stage renal failure.

Chronic renal failure is associated with an increased rate of premature death from cardiovascular disease. Non-invasive identification of asymptomatic cardiac disease should be valuable in the management of such patients, and in selection for transplantation. One hundred and three high-risk patients (66 male, 37 female) with chronic renal failure who were without cardiovascular symptoms were assessed by exercise-graded thallium myocardial perfusion imaging and followed prospectively for 4 years. The development of a cardiovascular event, or death, and the interval to event or death were recorded. Cardiovascular events were documented in 50 patients; in 44 of the 60 patients with a positive thallium test and in only six of the 43 patients with a negative thallium test (test sensitivity 88%, specificity 70%, predictive value of a positive test 73%). Forty patients died, 28 from cardiovascular causes, during the study period. Thallium myocardial perfusion imaging is of value in the prediction of future cardiovascular events in patients with chronic renal failure, and is a useful non-invasive screening technique in patients with end-stage renal failure being considered for transplantation.

Adult↗
PubMed1993

[The development of a computer model in the quantitative assessment of thallium-201 myocardial scintigraphy].

Thallium-201 scintigraphy is a widely used noninvasive procedure for the detection and prognostic assessment of patients with suspected or proven coronary artery disease. Thallium uptake can be evaluated by a visual analysis or by a quantitative interpretation. Quantitative scintigraphy enhances disease detection in individual coronary arteries, provides a more precise estimate of the amount of ischemic myocardium, distinguishing scar from hypoperfused tissue. Due to the great deal of data, analysis, interpretation and comparison of thallium uptake can be very complex. We designed a computer-based system for the interpretation of quantitative thallium-201 scintigraphy data uptake. We used a database (DataEase 4.2-DataEase Italia). Our software has the following functions: data storage; calculation; conversion of numerical data into different definitions classifying myocardial perfusion; uptake data comparison; automatic conclusion; comparison of different scintigrams for the same patient. Our software is made up by 4 sections: numeric analysis, descriptive analysis, automatic conclusion, clinical remarks. We introduced in the computer system appropriate information, "logical paths", that use the "IF ... THEN" rules. The software executes these rules in order to analyze the myocardial regions in the 3 phases of scintigraphic analysis (stress, redistribution, re-injection), in the 3 projections (LAO 45 degrees, LAT,ANT), considering our uptake cutoff, obtaining, finally, the automatic conclusions. For these reasons, our computer-based system could be considered a real "expert system".

Computer Simulation↗
PubMed1993

Dipyridamole-thallium stress testing: a local community hospital experience.

Clinical data on the first 100 patients who underwent dipyridamole-thallium stress testing in our hospital were reviewed in order to re-evaluate safety guidelines and diagnostic utility in patients with coronary artery disease. Forty patients developed symptoms, including three major ones. One patient had significant bronchospasm, and two others developed significant hypotension with near syncope. The rest had nonspecific chest, shoulder, arm or throat pain, dyspnea, nausea, vomiting, and paresthesia. Most symptoms occurred within the first 10 minutes of dipyridamole infusion. Twenty-eight patients required treatment with intravenous (IV) aminophylline. Of the remaining 60 patients, 30 became hypotensive but remained asymptomatic. Fourteen of 20 patients who underwent coronary angiography had coronary disease. Thirteen were correctly identified by thallium imaging, and only one was identified by electrocardiogram (EKG). Six patients' angiographies showed no evidence of coronary disease. Five of these patients developed perfusion abnormalities during thallium scintigraphy. These results suggest that dipyridamole is a relatively safe drug for pharmacologic stress testing even though the incidence of side effects is relatively high. The high incidence of thallium perfusion abnormalities in patients without coronary disease probably reflects bias in patient selection for coronary angiography, resulting in a relatively small sample of catheterized patients. However, this requires further investigation.

Aged↗
PubMed1993

Left ventricular cavity-to-myocardial count ratio: a new parameter for detecting resting left ventricular dysfunction directly from tomographic thallium perfusion scintigraphy.

Patients with reduced left ventricular function or aneurysms have cavities that appear dark on SPECT thallium scintigrams. We hypothesized that a quantitative index, which relates thallium activity in the left ventricular cavity to that in the myocardium (C/M ratio), could provide information on left ventricular function. A group of 80 patients who had both exercise SPECT thallium imaging and cardiac catheterization were studied. The C/M ratio was obtained from the short-axis tomogram on both exercise and rest images. Counts in a 2 x 2 pixel region of interest in the left ventricular cavity were divided by the number of counts in the "hottest" area of the myocardium. Plotting the angiographically determined ejection fraction against the C/M exercise and rest ratios, we observed a linear correlation between ejection fraction and both C/M ratios, r = 0.65 for C/M exercise and r = 0.67 for C/M rest ratio (p < 0.00001). Using data from 12 normal cardiac catheterization patients, we established the lower limit of normal; 50% for ejection fraction and 0.40 for the C/M ratios. A C/M exercise ratio < or = 0.40 identified 26 of 31 patients with an ejection fraction < or = 50%. A C/M exercise ratio > 0.40 identified 39 of 49 patients with an ejection fraction > 50%. These calculations yielded a sensitivity of 83% and specificity of 78% for the C/M exercise ratio. A similar analysis for C/M rest ratio revealed sensitivity of 61% and specificity of 92%. The present study shows that an abnormal C/M ratio correctly distinguishes patients with abnormal from normal ejection fractions with an accuracy of 81%. The C/M ratio is easily obtained, requires minimal processing time and is highly reproducible. These attributes may enable this index to add supplementary information regarding left ventricular function in addition to perfusion from thallium imaging.

Adult↗
PubMed1993

Abnormal thallium stress test and normal coronary angiograms: catheterization and clinical characteristics.

Left ventricular end-diastolic pressure at rest, left ventricular ejection fraction, thallium segmental abnormalities, as well as sex, age and presence of diabetes mellitus, hypertension, hypercholesterolemia and smoking excess were analyzed in 40 patients with abnormal thallium stress test and normal coronary angiograms. Of these patients, 25 had elevated left ventricular end-diastolic pressure and "low normal" ejection fraction (group 1), while the other 15 had normal left ventricular end-diastolic pressure and "high normal" ejection fraction (group 2). The left ventricular end-diastolic pressure was 18.1 +/- 4.5 mm Hg in group 1 vs. 8.5 +/- 2.4 mm Hg in group 2 (P < 0.000). The ejection fraction was 57.6 +/- 8.3% in group 1 vs. 63.9 +/- 9.1% in group 2 (P < 0.05). There was no difference between the groups in relation to the abnormal segment on thallium stress tests, aged and sex. Although the number of patients was too small for meaningful statistical analysis, most of the patients with diabetes mellitus, hypertension, hypercholesterolemia or smoking history were in group 1. Thus, the patient population with abnormal results on radionuclide exercise tests and angiographically normal coronary arteries probably comprises two groups: a) patients with decreased diastolic and relatively decreased systolic performances which might reflect coronary flow disturbances, and b) patients with normal diastolic and systolic performances, probably reflecting "true false positive thallium stress test".

Adult↗
PubMed1995

[Clinical implications of mismatched uptakes of beta-methyl fatty acid analogue and thallium in infarcted myocardium: correlations with coronary stenosis and regional wall motion abnormality].

Myocardial perfusion and fatty acid metabolism were assessed by using myocardial single-photon emission computed tomography with thallium and beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) during acute and/or late stages of myocardial infarction in 157 infarcted segments of 100 patients. The incidence of reduced thallium perfusion relative to BMIPP uptake ("T-type" mismatch) was significantly (p < 0.05) lower (9%) compared to that of reduced BMIPP uptake relative to thallium perfusion ("B-type" mismatch) (59%) or non-mismatched segment (32%). In an anteroseptal region, B-type dissociation had a significantly higher incidence compared to no or T-type mismatch; 68% vs. 27% vs. 5%, respectively, whereas the incidence of T-type uptake was relatively high in inferior and posterolateral regions; 13%, 11%, respectively. Severe coronary stenosis was observed in 76% of B-type segments and 72% of non-mismatched segments but in only 43% of T-type segments. The incidence of regional wall motion abnormality was significantly lower (46%) in the T-type mismatch segments when compared to the B-type (91%) or non-mismatched segments (96%). In conclusion, myocardial fatty acid metabolism was more markedly impaired compared to an involved coronary perfusion, resulting in the mismatch of perfusion and fatty acid metabolism. Coronary stenosis and regional wall motion abnormality are more closely related to "B-type" mismatch but not necessarily to "T-type" dissociation, probably because of attenuation artifacts in inferior and posterolateral regions in thallium scan.

Aged↗
PubMed1995

Prediction of early cardiac morbidity and mortality following aorto-iliac reconstruction: comparison between clinical scoring systems, echocardiography and dipyridamole-thallium scanning.

Preoperative cardiac assessment may be difficult in patients with aorto-iliac and/or peripheral vascular disease because of severe physical limitation due to the disease itself, advanced age, locomotor problems or because of beta-blocker usage. 216 patients with aorto-iliac occlusive disease were studied; several cardiac risk scoring systems were determined for each patient. Preoperative echocardiography was performed in 182 patients and thallium-scanning in 63 patients. The results from the preoperative risk factor evaluations, echocardiographies and thallium examinations were correlated individually with the postoperative observed cardiac complications. Overall mortality was 2.8% (4 patients died from myocardial infarction). A total of 13 major postoperative cardiac events (10 myocardial infarctions and 3 life-threatening arrhythmias) were registered. No statistical correlation could be identified between the patient's clinical examination nor the scoring system and the occurrence of postoperative cardiac complications. 12 events occurred out of 13 patients who were shown to have a reversible defect on the preoperative thallium scan. These patients also presented hypokinesia or akinesia on the preoperative echocardiography. Thallium imaging and echocardiography represent a valid preoperative test to evaluate the risk of cardiac morbidity and mortality in vascular patients. Coronary angiography is recommended in patients suffering from progressive and/or unstable angina.

Aged↗
PubMed1996

Thallium-201 and iodine-131 scintigraphy in differentiated thyroid carcinoma.

UNLABELLED: The purpose of this study was to determine the concordance and discordance between diagnostic 131I and 201TI whole-body scintigraphy in patients with differentiated carcinoma of the thyroid. METHODS: Following thyroidectomy for differentiated thyroid carcinoma, 50 patients underwent whole-body 131I and 201TI scanning (60 pairs of scans in total). Fifteen pairs of studies were obtained before ablative therapy, 30 pairs after ablative therapy and 15 pairs after 131I therapy for metastatic disease. Serum thyroglobulin levels were concurrently determined by radioimmunoassay. RESULTS: Thirty-six 131I whole-body scans (in 34 patients) showed residual uptake in the neck, but only six (17%) of the corresponding whole-body thallium studies had detectable uptake in the neck. Fourteen 131I scans (in nine patients) identified multiple metastatic lesions, whereas the thallium scans were interpreted as either negative, nonspecific or showing fewer lesions. In four study pairs, the thallium scans showed solitary lesions that were not detected by the corresponding radioiodine scans. In 16 scans, the thallium studies gave false-positive results. CONCLUSION: Iodine-131 scintigraphy for differentiated thyroid carcinoma is more sensitive and more specific than 201TI scintigraphy for detection of distant metastases and residual activity in the neck following thyroidectomy.

Adenocarcinoma, Follicular↗