Scintigraphic Variables Research Articles

Salivary gland scintigraphy in subjects with and without symptoms of dry mouth and/or eyes, and in patients with primary Sjögren's syndrome.

The major salivary glands were examined with 99m-Tc-pertechnetate scintigraphy in randomly selected subjects with (n = 30) and without (n = 12) symptoms of dry mouth and/or eyes, and in patients with primary Sjögren's syndrome (1 degree SS, n = 17). The scans were quantitatively evaluated and compared to other objective tests used to diagnose 1 degree SS. As compared with those for asymptomatic subjects, most values for the scintigraphic variables were non-significantly lower for symptomatic subjects and the time-activity curves were slightly flatter for all major salivary glands. In patients with 1 degree SS most values for the scintigraphic variables were significantly lowered and the submandibular glands were the glands most affected, as reflected in a flat time-activity curve, while the parotid glands were mainly affected during stimulated secretion. The scintigraphic variables correlated with the self-rated dryness of mouth in symptomatic subjects and with the abnormality of sialometry results in patients with 1 degree SS. We conclude that salivary gland scintigraphy is a sensitive and valid method to measure salivary gland function and abnormalities.

Improvement of diagnosis in the non-invasive assessment of coronary artery disease: enhanced evaluation of quantitative exercise 201thallium imaging by multivariate analysis

The aim was to evaluate discriminant analysis, performed in patients without prior myocardial infarction, in enhancing the diagnostic value of quantitative exercise 201thallium scintigraphy. All clinical, electrocardiographic, and scintigraphic variables were first subjected to a univariate analysis. Afterwards a discriminant analysis was done. 135 patients (104 male) were studied. Age was 24-70 years, mean 55 years. Two discriminant analyses were done. In the first analysis, the ability to detect the presence of coronary artery disease was tested. Significant variables were: (1) history of angina, (2) sex, (3) quantitative analysis of 201thallium scintigraphy, (4) age, (5) ischaemic ST response, (6) angina during the test, and (7) the pressure-rate product. The sensitivity, specificity, and accuracy of classification using the discriminant function were 91%, 87%, and 90%, respectively. The sensitivity was higher than when using only visual interpretation (sensitivity 70%; p less than 0.0002) or quantitative interpretation (sensitivity = 66%; p less than 0.0001) of thallium scans, without significant loss of specificity (p less than 0.5488; p less than 0.6875). In the second analysis, a discriminant function was calculated to detect multivessel disease. Five input variables were selected: (1) number of vessels with stenosis predicted by quantitative analysis, (2) number of vessels with stenosis predicted by visual analysis, (3) ischaemic ST response, (4) sex, (5) angina during the test. Multivariate analysis showed an increase in sensitivity when compared with visual interpretation (78% v 55%; p less than 0.0043) and quantitative analysis (66%; p less than 0.0156). Using the classification, the discriminant function was more accurate than visual analysis (81% v 69%) or quantitative analysis (77%). The results show that multivariate analysis of non-invasive test results in quantitative thallium exercise testing allows convenient use for clinical purposes with improved results.

The frequency of late reversibility in SPECT thallium-201 stress-redistribution studies

The frequency of thallium-201 late reversibility was prospectively assessed in 118 patients who had stress-redistribution thallium-201 studies by single photon emission computed tomography (SPECT). These patients demonstrated two or more segments with nonreversible defects at 4 h imaging and underwent late (18 to 72 h) redistribution imaging. When the criterion of late reversibility was defined as greater than or equal to 1 segment with 4 h nonreversible defects demonstrating late reversibility, it was present in 62 (53%) of the 118 patients and 164 (22%) of 762 segments. When the criterion of greater than or equal to 2 segments was used, late reversibility was found in 41 (35%) of 118 patients and 143 (19%) of 762 segments. The frequency of detected reversible defects increased from 27% at 4 h imaging to 43% at combined 4 h and late imaging (p less than 0.0001) and was significantly increased in all myocardial regions. In comparing the efficacy of initial and late imaging alone versus performing initial, 4 h and late imaging for the identification of reversible defects, 421 (94%) of 449 segments classified as reversible by the latter protocol were also correctly identified by the early and late imaging only approach, with the remaining 6% (28 segments) comprising those segments demonstrating the reversible pattern at 4 h and the nonreversible pattern at late imaging. No major differences were noted with respect to clinical, stress electrocardiographic and scintigraphic variables between the 118 patients undergoing late imaging and 98 additional randomly selected patients with two or more nonreversible defects at 4 h, who did not have late imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic importance of silent myocardial ischemia detected by intravenous dipyridamole thallium myocardial imaging in asymptomatic patients with coronary artery disease

One hundred seven asymptomatic patients who underwent intravenous dipyridamole thallium imaging were evaluated to determine prognostic indicators of subsequent cardiac events over an average follow-up period of 14 ±10 months. Univariate analysis of 18 clinical, scintigraphic and angiographic variables revealed that a reversible thallium defect, a combined fixed and reversible thallium defect, number of segmental thallium defects and extent of coronary artery disease were significant predictors of subsequent cardiac events. Of the 13 patients who died or had a nonfatal infarction, 12 had a reversible thallium defect.Stepwise logistic regression analysis selected a reversible thallium defect as the only significant predictor of cardiac events. When death or myocardial infarction was the outcome variable, a combined fixed and reversible thallium defect was the only predictor of outcome. In patients without previous myocardial infarction, the cardiac event rate was significantly greater in those with an abnormal versus normal thallium scan (55% versus 12%, p < 0.001).Thus, intravenous dipyridamole thallium scintigraphy is a useful noninvasive test to risk stratify asymptomatic patients with coronary artery disease. A reversible thallium defect most likely indicates silent myocardial Ischemia in a sizable fraction of patients in this clinical subset and is associated with an unfavorable prognosis.

Prognostic value of intravenous dipyridamole thallium scintigraphy after an acute myocardial ischemic event

Seventy-seven patients recovering from an acute coronary event were studied by intravenous dipyridamole thallium scintigraphy to evaluate the prognostic value and safety of the test in this patient subset. Forty-four patients (58%) had unstable angina and 33 (42%) had an acute myocardial infarction. One death occurred within 24 hours of testing. Sixty-eight patients were followed for an average of 12 months; 25, 31 and 23% had a fixed, reversible or combined thallium defect on their predischarge thallium scan. During follow-up, 10 patients died or had a nonfatal myocardial infarction; in each case, a reversible or combined myocardial thallium defect was present. Univariate analysis of 17 clinical, scintigraphic and angiographic variables showed that a reversible thallium defect and the angiographically determined extent of coronary artery disease were predictors of future cardiac events. The extent of coronary disease and global left ventricular ejection fraction were predictors of subsequent reinfarction or death. Logistic regression analyses revealed that a reversible thallium defect (p < 0.001) and the extent of coronary disease (p < 0.009) were the only significant predictors of a cardiac event. When death or reinfarction were the outcome variables, the extent of coronary disease (p < 0.02) and left ventricular ejection fraction (p < 0.06) were the only variables selected. Thus, intravenous dipyridamole thallium scintigraphy after an acute coronary ischemic syndrome is a useful and relatively safe noninvasive test to predict subsequent cardiac events.

Usefulness of exercise electrocardiography and thallium scintigraphy in unstable angina pectoris in predicting the extent and severity of coronary artery disease

The safety and efficacy of exercise electrocardiography and thallium scintigraphy early in the course of unstable angina pectoris were assessed 4.6 ± 1.6 days after admission in 67 patients with unstable angina that stabilized after medical therapy. Coronary arteribgraphy was performed in all patients 5.4 ± 2.4 days after admission. There was no difference in clinical, exercise or scintigraphic variables between patients with stenoses <50% and patients with 1-vessel coronary artery disease (CAD) defined as a diameter stenosis ≥50.%. Patients with 3-vessel CAD had a significantly shorter exercise duration than patients with <50%-diameter narrowing (5.5 ± 2.2 vs 8.3 ± 3.3 minutes, respectively), lower exercise heart rate (119 ± 20 vs 149 ± 22 beats/min) and systolic blood pressure (156 ± 29 vs 166 ± 33 mm Hg), more frequent chest pain (76 vs 20%) and more pronounced ST depression (−1.48 ± 1.37 vs −0.33 ± 0.72 mm). In addition, thallium defect size on exercise was greater in the patients with 2-vessel CAD (159 ± 132 °) and 3-vessel CAD (255 ± 132 °) than in patients with no CAD (28 ± 319 °) or 1-vessel CAD (73 ± 78 °), p ≥0.05. Multiple regression analysis demonstrated that thallium defect size was the best predictor of extent of CAD, with exercise heart rate and presence of chest pain during exercise also predictive of extent of CAD. Exercise testing was deemed safe in patients with unstable angina who have been medically stabilized and thallium defect size was considered the best predictor of extent of CAD.

Functional significance of predischarge exercise thallium-201 findings following intravenous streptokinase therapy during acute myocardial infarction

The purpose of this study was to determine which predischarge exercise thallium-201 imaging pattern(s) best correlate with myocardial salvage following intravenous streptokinase therapy (IVSK). Myocardial salvage was defined as improvement in regional left ventricular function determined by two-dimensional echocardiography between the time of admission and time of discharge in 21 prospectively studied patients receiving IVSK within 4 hours of chest pain. all patients had coronary angiography 2 hours following IVSK. Whereas 16 of the 21 patients (76%) had patent infarct-related vessels, only seven (33%) showed significant improvement in regional function at hospital discharge. Eleven patients demonstrated persistent defects (PD), and five each showed delayed and reverse redistribution. Patients with both delayed and reverse redistribution demonstrated significant improvement in regional left ventricular function score, while those with PD did not (+3.9 ± 3.3 versus −0.5 ± 2.9, p = 0.004). All other clinical, exercise, electrocardiographic, scintigraphic, and angiographic variables were similar between all patients, with the exception of the interval between chest pain and the institution of IVSK, which was longer in patients with reverse compared to delayed redistribution (3.5 ± 0.4 versus 2.2 ± 0.4 hours, p = 0.001). It is concluded that both delayed and reverse redistribution seen on predischarge exercise thallium-201 imaging are associated with myocardial salvage, defined as serial improvement in regional systolic function. Despite a high infarct vessel patency rate in patients with acute myocardial infarction receiving IVSK within 4 hours of onset of symptoms, only one third demonstrated improvement in regional function that was associated with either delayed or reverse redistribution seen on predischarge exercise thallium-201 imaging.

Sex differences in exercise induced left ventricular dysfunction in patients with syndrome X.

Clinical, electrocardiographic, and scintigraphic data were reviewed from 32 patients (18 men and 14 women) who had syndrome X (chest pain, evidence of ischaemia, and normal coronary arteries without coronary vasospasm). The mean (SD) resting left ventricular ejection fraction, determined by first pass radionuclide angiography was 62.6 (9.2)% and was greater than 50% in all subjects. There was no significant difference between men and women. On exercise, left ventricular ejection fraction decreased significantly to 57.4 (13.0)%. In 17 of 32 subjects there was a fall in left ventricular ejection fraction of greater than 5%, and regional wall motion abnormalities developed in 12 subjects. The fall in left ventricular ejection fraction on exercise was significant in women (from 61.9 (8.5)% at rest to 54.0 (9.8)% on exercise) but not in men (from 63.2 (9.8)% at rest to 60.0 (14.8)% on exercise). Exercise left ventricular ejection fraction fell by greater than 5% in 10 (71%) of 14 women and in seven (39%) of 18 men. Dyskinetic segments developed in eight (57%) of 14 women and only four (22%) of men. Exercise duration in women was significantly shorter than in men (4.1 (1.5) vs 6.6 (2.1) minutes) and was the only one of several clinical and scintigraphic variables that correlated with the change in left ventricular ejection fraction on exercise. In this selected group of subjects with chest pain and angiographically normal coronary arteries, exercise induced left ventricular dysfunction, as shown by a fall in ejection fraction or the development of regional abnormalities, is a common finding. These are more likely to occur in women than men and are associated with a lower exercise capacity. The data suggest that the sex of the patient is important in the interpretation of the non-invasive evaluation of subjects suspected of having syndrome X.

Complementary role of thallium-201 scintigraphy to predischarge exercise electrocardiography for patients stratification after a first myocardial infarction.

The value of a predischarge exercise test combined with thallium-201 myocardial scintigraphy in detecting patients with severe multivessel disease (MVD) was studied in 58 consecutive patients discharged after a first acute myocardial infarction. Twelve electrocardiographic, clinical and scintigraphic variables were analysed. Angiography at one month revealed MVD (greater than 70% narrowing in vessels unrelated to infarction) in 26 patients (45%). ST segment depression of 1mm or greater, thallium defects in multiple vascular distributions (MVTL), and reversible thallium defects in a vascular distribution different from the infarct related vessel predicted patients at risk for MVD (predictive value respectively of 68%, 65% and 75%). The other variables were not significantly associated with the presence of MVD. Only ST segment depression and thallium defects in multiple vascular distributions emerged as independent predictors of MVD. Their combination yielded a 77% sensitivity and a 59% specificity for MVD. Combination of thallium imaging with the predischarge exercise ECG significantly improved the stratification provided by the exercise test alone (P less than 0.05). A positive thallium scan (MVTl defects) associated with a positive ECG (ST depression) carried a risk for MVD of 80% in the population studied. When both tests were negative, MVD was infrequent (risk 22%). Because improvement in the stratification of patients is not as clear as expected from studies performed at a later stage, it appears that exercise thallium scintigraphy at a submaximal level one or two weeks after infarction does not provide optimal information. Predischarge exercise thallium-201 scintigraphy, however, is superior to an exercise tolerance test alone in separating patients into those with high and low risk of MVD.

Prognostic value of submaximal exercise radionuclide ventriculography after myocardial infarction

Submaximal exercise testing with radionuclide ventriculography (RVG) was performed in 117 patients before hospital discharge 17 ± 7 days (± standard deviation) after an acute myocardial infarction (MI). The hypothesis tested in these studies was that submaximal exercise testing coupled to RVG allows the identification of patients at risk for future ischemic events in the subsequent 6 months, irrespective of MI location and type. The sites of MI were characterized as anterior transmural in 33, inferior transmural in 39, limited nontransmural in 18, extensive nontransmural in 24 and indeterminant in 3. During 6 months of follow-up, 9 patients died, 14 had recurrent MI, 18 had refractory angina pectoris, 16 had limiting angina and 17 had congestive heart failure. Discriminant function analysis ranked exercise changes in left ventricular (LV) ejection fraction and end-systolic volume the most important of all clinical, exercise and scintigraphic variables for predicting future cardiac events. The predictive accuracy of changes in LV ejection fraction and end-systolic volume were 93 and 91%, respectively, for the entire group, and were significantly more sensitive than any degree of ST-segment depression or elevation (p < 0.001). These findings were generally independent of MI location and type. Thus, submaximal exercise RVG after MI is an accurate means of identifying patients at risk for major cardiac events in the 6 months after hospital discharge.

Enhanced detection of proximal right coronary artery stenosis with the additional analysis of right ventricular thallium-201 uptake in stress scintigrams

The value of right ventricular thallium-201 analysis in detecting proximal right coronary artery stenosis in exercise myocardial scintigraphy was analyzed in 52 patients, 27 with and 25 without proximal right coronary artery stenosis. For the detection of proximal right coronary artery stenosis, the sensitivity and specificity of thallium scintigraphic analysis were 59 and 88% for a right ventricular abnormality, 67 and 68% for a left ventricular inferior wall abnormality, and 93 and 56% for an abnormality of either. When both right and left ventricular thallium images were abnormal, all 9 patients had proximal right coronary artery stenoses, and when both were normal, 26 of 28 patients had a normal proximal right coronary artery. The sensitivity and specificity of blood pool scintigraphic variables during exercise (right ventricular ejection fraction and left ventricular inferior wall motion) were not significantly different for detection of proximal right coronary artery stenosis.Thus, the additional analysis of the right ventricle on thallium-201 stress scintigrams can improve the detection of proximal right coronary artery stenosis. When both right ventricular and left ventricular thallium scintigrams are abnormal (or normal), the ability to predict the presence (or absence) of proximal right coronary artery stenosis is very high.

The late prognostic value of acute scintigraphic measurement of myocardial infarction size.

Infarct, perfusion and blood pool scintigraphy were performed in 62 patients during hospitalization for acute myocardial infarction. The largest measured infarct or perfusion image defect and left ventricular ejection fraction were related to the late prognosis determined a mean of 16 months after the event. Breakpoint values for all scintigraphic variables could separate those who were asymptomatic on follow-up from those who died. The best indicators for selection of survivors and nonsurvivors were a scintigraphic infarct size greater than or equal to 25 cm2 and a perfusion abnormality greater than or equal to 35% of the projected left ventricular area. Among patients with perfusion abnormalities above this limit, 61% died; 93% of those with small perfusion abnormalities survived. Scintigraphic measurements of relative myocardial perfusion and function best separated patients asymptomatic on follow-up from those who developed heart failure and also best identified those with an unfavorable evolution, who developed heart failure or died. Early scintigraphic parameters appeared more accurate than other clinical laboratory indicators for determining late prognosis and could be important in planning treatment after acute infarction.

Identification of patients with coronary artery disease using a scoring system of coronary risk factors, electrocardiography and myocardial perfusion imaging.

To determine whether clinical variables of coronary risk factors and electrocardiographic and scintigraphic findings could reliably detect the presence of coronary artery disease and of coronary stenosis in the individual coronary arteries, 11 clinical and 7 electrocardiographic and scintigraphic variables were compared with the findings of coronary angiography in 107 patients. Sixty-seven patients had angiographic evidence of coronary artery disease and forty did not. Exercise electrocardiograms were diagnostic in 43 patients (64%) and exercise thallium-201 scintigraphy in 56 (84%). A coronary scoring using all the above variables based on multiple discriminant analysis increased the diagnostic accuracy (sensitivity 96% and specificity 95%). This scoring system was applied to a prospective series of 59 cases with similarly selected patients. Fifty-five cases (93%) were correctly diagnosed. The coronary scoring system to assess the stenosis of individual arteries was less satisfactory and 51 cases (86%) of the right coronary, 51 (86%) of the left anterior descending and 44 (75%) of the left circumflex artery were accurately diagnosed. It is concluded that statistical multivariate analysis of clinical, electrocardiographic and scintigraphic variables facilitates the detection of coronary artery disease and that this scoring system is helpful in assessing the probability of individual coronary artery involvement.