Search

Unlabelled: 99mTcN-NOET (bis[N-ethoxy,N-ethyl]dithiocarbamato nitrido technetium (V)) has been proposed for myocardial perfusion imaging. Biodistribution, safety, and dosimetry were studied in 10 healthy volunteers (5 at rest and 5 during exercise)., Methods: Biodistribution was studied by acquiring dynamic images up to 60 min after injection and whole-body images up to 24 h after injection. The MIRDOSE3 analysis program was used for radiation dosimetry calculations., Results: Safety parameters measured to 48 h after injection revealed no clinically significant changes. Cardiac uptake of 99mTcN-NOET was high (2.9%-3%), with biologic half-life of 210-257 min on average. Lung uptake of 99mTcN-NOET was higher (10%-20%) but, on average, biologic half-life was shorter (1-77 min). Clearance from the blood was rapid (5% by 5 min). Radiation dosimetry calculations indicated an effective absorbed dose of 5.11 x 10(-3) mSv/MBq at rest and 5.38 x 10(-3) mSv/MBq after exercise., Conclusion: 99mTcN-NOET exhibits high cardiac uptake and an estimated effective absorbed dose comparable with that of the other 99mTc-labeled compounds used in myocardial perfusion imaging.

The incidence of major cardiac events (death, infarction) is over 5% after programmed aortic vascular surgery. The aim of this study was to evaluate a management strategy of this risk based on the clinical status and targeted indication of myocardial scintigraphy, coronary angiography and myocardial revascularisation. A first phase (1991-1993, 451 patients) confirmed the prognostic value of clinical (age, previous cardiac history, diabetes, hypertension, electrocardiogrammes) and scintigraphic features: the cardiac mortality was 1.25% in patients with a low clinical risk (70.3% of cases) and 4.5% in patients with a high clinical risk (2 factors, 29.3% of cases) (p < 0.01). In the latter group, the mortality was zero after normal myocardial scintigraphy and 7.2% after abnormal myocardial scintigraphy (p < 0.01) and 12.5% in cases with reversible defects (p < 0.01). During the second phase of the study (1994-1997, 531 patients) coronary angiography was performed in patients with a high clinical risk and abnormal scintigraphy (10.9% of cases). This led to a myocardial revascularisation in 3.6% of patients. The cardiac mortality was then the same in the low and high a priori clinical risk: 2.3 and 2.8% (NS). The use of simple clinical criteria enables surgery in the majority of candidates for aortic vascular surgery, scintigraphy being reserved for about one patient in ten with myocardial revascularisation in less than 4% of cases. The operative cardiac mortality then decreases to under 2.5%.

Objective: We evaluated the prognostic value of an exercise stress test and thallium-201 scintigraphy for the prediction of cardiac events in selected high-risk NIDDM patients., Research Design and Methods: NIDDM patients (n = 158, 105 men, aged 63 +/- 9 years) with two or more of the following criteria were prospectively included: age > or = 65 years, active smoking, hypertension > 160/95 mmHg, hypercholesterolemia (cholesterol > 5.70 mmol/l or LDL > 3.10 mmol/l), peripheral artery disease, abnormal rest electrocardiogram, or microalbuminuria (20-200 micrograms/min). An exercise-stress scintigraphy was performed in 77 patients able to exercise, while a dipyridamole scintigraphy was performed in 80 patients unable to exercise. Follow-up was 23 +/- 17 months. Major end points were cardiac deaths or nonfatal myocardial infarction., Results: The annual event rate was 7.31% (deaths: 8, myocardial infarction: 14). Independent predictors of events were as follows: an age > 60 (P = 0.02), an abnormal rest electrocardiogram (P = 0.02), microalbuminuria (P = 0.001), the inability to exercise (P = 0.009), and the presence of more than two defects on scintigraphy (P = 0.001). A cardiac death occurred in 1.3% of patients able to exercise versus 8.8% of patients unable to exercise (odds ratio = 6.8, P = 0.001). Among patients unable to exercise, large perfusion defects corresponded to an annual mortality rate of 22.3%. Conversely, the negative predictive value of a normal scintigraphy for the occurrence of death was 97%., Conclusions: Inability to exercise and large perfusion defects on thallium-201 scan are major predictors of future death and myocardial infarction in high-risk NIDDM patients.

The best test presently available to ascertain residual viability within an infarct-related area involves the use of fluorine-18 fluorodeoxyglucose (FDG) to detect the persistence of some cellular metabolism. Rest reinjection of thallium-201 is a less accurate alternative but is easy to perform. Iodinated fatty acids, which are used with standard gamma cameras, are proposed as markers of cellular metabolism. This study was performed to assess the value of 16-iodo-3-methylhexadecanoic acid (MIHA) as a marker of the residual cellular metabolism by comparison with FDG in patients with a recent myocardial infarction, and to evaluate its contribution compared with the 201Tl stress-redistribution-reinjection technique. Stress-redistribution-reinjection 201Tl imaging, rest MIHA imaging and glucose-loaded FDG imaging were performed in 22 patients with recent myocardial infarction. Out of the 628 myocardial segments obtained from the left ventricular analysis, 400 were hypoperfused (relative uptake <0.75 of maximum uptake on stress 201Tl imaging), 177 of which were severely hypoperfused (relative uptake <0.50). Receiver operating characteristic (ROC) curves for predicting metabolic myocardial viability with FDG were derived from the results in respect of (a) 201Tl activity during exercise, redistribution and reinjection and (b) MIHA uptake, using the two FDG thresholds most commonly considered to define metabolic viability (0.50 and 0.60). Analysis of the 400 hypoperfused segments demonstrated that 201Tl reinjection was the most accurate test in predicting the presence of myocardial viability (area under the ROI curves=0.85 and 0.86 at the 0.50 and 0.60 FDG thresholds, respectively; P<0.05 vs other tests). The global predictive values of MIHA and 201Tl reinjection were, respectively, 0.87 and 0.89 at the 0.50 FDG threshold (NS), and 0.82 and 0.87 at the 0.60 FDG threshold (NS). When only the 177 severely hypoperfused segments were considered, 201Tl reinjection remained the most accurate test (accuracy 0.84 at the 0.50 FDG threshold and 0.82 at the 0.60 FDG threshold), while the accuracy of MIHA decreased significantly (0.78 at the 0.50 FDG threshold and 0.73 at the 0.60 FDG threshold, P<0.05 vs 201Tl reinjection). In all circumstances, MIHA was less specific than 201Tl reinjection for the detection of metabolic viability. In conclusion, in patients with recent myocardial infarction, MIHA accurately detects the persistence of metabolic viability, but is not superior to 201Tl.

Objectives: This study was designed to assess the prognostic value of thallium-201 single-photon emission computed tomographic (thallium SPECT) perfusion imaging in patients evaluated for stable angina pectoris and to examine the relation, if any, between the presence and extent of myocardial defect and future fatal or nonfatal cardiovascular events (revascularization, secondary myocardial infarction)., Background: Compared with planar scintigraphy, thallium SPECT enables better evaluation of the extent of myocardial perfusion defect. However, its prognostic value has not yet been studied in a large population of patients., Methods: Between 1987 and 1989 we studied 3,193 patients. After exclusion of patients with unstable angina, myocardial infarction during the previous month or earlier revascularization, 1,926 patients were followed up for 33 +/- 10 (mean +/- SD) months after stress thallium SPECT imaging (performed after exercise in 1,121 patients or during dipyridamole infusion in 805 patients). Thallium SPECT imaging of the left ventricle was divided into six segments., Results: After normal thallium SPECT imaging (715 patients), the annual total and cardiovascular mortality rates were, respectively, 0.42%/year and 0.10%/year and were significantly higher after abnormal thallium SPECT imaging (respectively, 2.1%, relative risk 5, p = 0.012; 1.5%, relative risk 15, p < 0.0001 [log-rank test]). There was a significant relation between the number of abnormal segments and cardiovascular mortality during follow-up (p < 0.02) or the occurrence of nonfatal events (p < 0.001). The extent of defect on the initial scan provided the best SPECT variable for long-term prognosis. Thallium SPECT imaging provided additive prognostic information compared with other clinical variables (gender, previous myocardial infarction) and exercise electrocardiogram., Conclusions: In patients with stable angina, normal thallium SPECT imaging indicates a low risk patient, and the extent of myocardial defect is an important prognostic predictive factor.

Thirty patients with recent myocardial infarction were intravenously injected with the modified fatty acid [123I]16-iodo-3R,S-methyl hexadecanoic acid (MIHA) at peak exercise to quantify viable myocardium after infarction. The results were analysed visually and quantitatively and compared with those obtained after injection of thallium 201 at peak exercise with single-photon emission computed tomography (SPECT) imaging immediately and 4 hours later. Ventriculography was used to study regional wall motion in all patients. In the visual comparison of 201Tl- and MIHA-SPECT scintigrams, 98.8% of normal segments (N) and 96% of temporary thallium-defect segments (T) were N or T on MIHA-SPECT scintigrams (91.3% and 70.5%, respectively, in the quantitative analyses). In contrast, 47.2% of permanent thallium-defect segments (P) were N or T on the MIHA-SPECT scintigrams (20.6% in the quantitative analysis). Revascularization therapy could only be recommended on the basis of MIHA-SPECTs in 5 to 8 of the 30 patients. To confirm the superiority of MIHA over 201Tl to evaluate myocardial viability, one must compare their uptake with myocardial contractility after revascularization.

The aim of this study was to compare the diagnostic value of exercise stress testing, Thallium 201 myocardial scintigraphy or after administration of dipyridamole and left ventricular angioscintigraphy performed either during a static (handgrip) or dynamic exercise (bicycle ergometry) for the positive diagnosis of stenosing coronary artery disease. The exercise angioscintigraphy was performed at equilibrium with 99m Tc red blood cell labelling. The global ejection fraction and that of seven radial segments of the left ventricle were measured, the data being recorded within a period of 2 minutes. The handgrip consisted in compressing a dynamometric ball at 1/3 maximal force for 3 minutes, with both hands; the ergometric exercise was increased by 30 Watt 2 minute increments until a positive ECG or 85% of the theoretical maximal heart rate for age was obtained. Normal subjects (n = 29) increased their global (+ 8%) and regional ejection fractions in each of the seven segments (p less than 0.05) during ergometric exercise: there was no significant change of global (-3% NS) or segmental ejection fractions during the handgrip exercise. In the coronary group (at least one greater than 70% stenosis) (n = 61) the fall in global ejection fraction was the same (-14%) with both forms of exercise; a similar fall in the segmental ejection fraction in the territory distal to the stenosis was observed with the handgrip (-22%) and bicycle ergometry (-28% NS). Dynamic exercise testing seemed superior to handgrip exercise. Therefore, the finding of an abnormal global ejection fraction on exercise (i.e. either a global ejection fraction less than the lower limit of normal on exercise, or lower than the global ejection fraction at rest), or of an abnormal regional ejection fraction (i.e. either a regional ejection fraction less than the lower limit of normal over at least 3 segments, or a regional ejection fraction on exercise lower than the regional ejection fraction at rest over at least 3 segments) detected coronary artery disease with a sensitivity of 94% and a specificity of 72%. Dynamic exercise angiography seemed to be more sensitive than maximal ECG stress testing (94% compared to 64%) more rapidly positive (p less than 0.05), as sensitive (94% compared to 83% NS) than Thallium myocardial scintigraphy, but less specific (72% compared to 90%, p less than 0.05), and as unspecific as ECG stress testing.(ABSTRACT TRUNCATED AT 400 WORDS)