Significance of diffuse slow washout in dipyridamole loading thallium-201 myocardial perfusion scintigraphy

To assess the significance of diffuse slow washout (DSW) in dipyridamole loading thallium-201 myocardial perfusion scintigraphy, 382 patients were studied. DSW were observed in 69 (24%) of 285 patients with perfusion defects, 5 (5%) of 97 patients without perfusion defects. There was significant relation between DSW and perfusion defects (p less than 0.01). Coronary angiography showed multivessel disease in 84% single vessel disease in 12% of patients with DSW and multivessel disease in 28%, single vessel disease in 50% of patients without DSW. During a mean follow up period of 29 months, initial CABG or PTCA were done in 41%, cardiac death occurred in 12%, nonfatal cardiac events occurred in 7% of patients with DSW and perfusion defects. In patients without DSW, initial CABG or PTCA were done in 11%, cardiac death occurred in 7%, nonfatal cardiac events occurred in 5%. Patients without perfusion defects had good prognosis regardless of the presence or absence of DSW. In conclusion, DSW indicates serious cardiac ischemia in patients with perfusion defects. DSW does not indicate cardiac ischemia in patients without perfusion defects.     

Tomographic myocardial perfusion scintigraphy in children with Kawasaki disease

Myocardial infarction and stenotic coronary lesions are serious late complications in children with Kawasaki disease. For the noninvasive assessment of myocardial perfusion, dipyridamole-redistribution 201Tl emission computed tomography (ECT) was performed in seven children (age 2 8/12-8 7/12 yr) 3-20 mo after the acute stage of the disease. In all patients, coronary aneurysms had been demonstrated by cross-sectional echocardiography. The scintigrams of six children showed no significant regional reduction of myocardial thallium uptake. These children had remained asymptomatic since the acute stage of Kawasaki disease. Persistent and transient thallium defects were present in one child with documented myocardial infarction. For this patient, obstruction of corresponding coronary vessels was confirmed by contrast angiography. It is suggested, that 201Tl ECT after dipyridamole-induced vasodilation may be used as a safe alternative to invasive coronary angiography for follow-up investigations in patients with Kawasaki disease.     

Diagnostic accuracy of stress first-pass contrast-enhanced myocardial perfusion MRI compared with stress myocardial perfusion scintigraphy

OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of stress perfusion MRI acquired with saturation-recovery prepared turbo fast low-angle shot (turbo FLASH) compared with stress myocardial perfusion scintigraphy. Recent studies show that first-pass contrast-enhanced myocardial perfusion MRI can provide noninvasive detection of low-limiting stenosis in the coronary artery. MATERIALS AND METHODS: First-pass contrast-enhanced MR images were acquired at rest and during stress in 40 patients with suspected coronary artery disease. All patients underwent thallium-201 SPECT without attenuation correction and coronary angiography. Two reviewers independently assigned one of five confidence grades without knowing the results of coronary angiography for receiver operating characteristic (ROC) analysis. Luminal stenosis >70% on coronary angiography was used as a reference standard. RESULTS: On coronary angiography, 70% or greater diameter stenosis of the coronary artery was observed in 21 (52.5%) of 40 patients. The areas under the ROC curve for detection of significant stenosis in the individual coronary artery were 0.86 (observer 1) and 0.84 (observer 2) for MRI. These values were 0.79 (observer 1, p = not significant) and 0.72 (observer 2, p = not significant) for 201Tl SPECT. CONCLUSION: The diagnostic accuracy of stress perfusion MRI acquired with saturation-recovery-prepared turbo FLASH was comparable with that of stress 201Tl SPECT. Stress first-pass contrast-enhanced MRI is a noninvasive technique that can be used as an alternative to stress myocardial perfusion scintigraphy.     

Dobutamine combined with low-level exercise for myocardial perfusion scintigraphy

Increased abdominal background activity is one of the limitations of dobutamine myocardial perfusion scintigraphy which may interfere with interpretation of the images. In this study, we evaluated the value of low-level exercise supplementation to dobutamine infusion in improving image quality. The control group (n = 32, Group A) received dobutamine alone, while the study group received dobutamine plus low-level exercise for the last 2 min of dobutamine administration (n = 26, Group B). One hundred and eleven MBq of 201Tl was injected 1 min before cessation of peak dose. The ratios of cardiac/hepatic (C/HEP), cardiac/subdiaphragmatic (C/INF) and cardiac/pulmonary (C/PUL) were calculated from anterior planar images taken immediately following the test. Cardiac/non-cardiac activity was also visually graded on a three-point scale. Visual evaluation showed improved cardiac/non-cardiac ratios as confirmed by significantly higher C/HEP and C/INF ratios for Group B (1.5+/-0.3 and 1.7+/-0.2, respectively) compared to corresponding values in Group A (1.2+/-0.4 and 1.4+/-0.4, respectively) (P<0.05). The cardiac/pulmonary (C/PUL) ratio was also higher for Group B (2.3+/-0.5) as compared to corresponding value in Group A (2.0+/-0.6, respectively), but this difference did not reach statistical significance (P > 0.05). No difference in the frequency of side effects and ECG changes were detected between the two groups (P > 0.05). Low-level exercise supplementation to dobutamine infusion for myocardial perfusion scintigraphy is a safe method and leads to a significant decrease in uptake by the areas adjacent to the heart, improving image quality.     

Digital subtraction angiography in abnormal perfusion scintigraphy of the lungs

A normal lung perfusion isotope scan can exclude pulmonary emboli. However, the demonstration of lung emboli presents problems, as an abnormal lung perfusion scan can have various causes. Some of these can be excluded if the perfusion scan is assessed in combination with a chest X-ray and a ventilation scan. In this study, 21 patients with an abnormal perfusion scan were also examined using digital subtraction angiography (DSA) of the lungs. With the help of DSA it was possible to differentiate between the various causes of a lung perfusion defect on the isotope scan by having a sufficiently reliable pulmonary angiogram. From experience it appears that the quality of the pulmonary angiogram confined to the first three divisions obtained with DSA, is comparable with that from a conventional pulmonary angiogram. A perfusion isotope scan is the initial screening modality for suspected lung emboli, if this shows an abnormality, DSA seems to be indicated as the next step.     

99Tcm-MIBI静息心肌断层显像对年轻心肌梗死患者心肌损伤的评价

目的　用99Tcm 甲氧基异丁基异腈 (MIBI)静息SPECT显像评价年轻心肌梗死患者的心肌损伤。方法　总结分析了 42例年龄 <40岁的心肌梗死患者99Tcm MIBI静息心肌灌注断层显像 ,并与冠状动脉造影和ECG进行比较。结果　 42例年轻心肌梗死患者 ,90 % (38例 )心肌灌注显像异常 ,10 % (4例 )未见明显异常 ,诊断灵敏度为 90 %。与ECG相比 ,心肌灌注显像对梗死灶定位更准确 ,特别是心尖和后壁梗死。结论　心肌灌注显像显示年轻心肌梗死患者心肌受损较严重。     

Fractional flow reserve and myocardial viability as assessed by SPECT perfusion scintigraphy in patients with prior myocardial infarction

Background

In patients with previous myocardial infarction (MI), assessment of myocardial viability and physiological significance of coronary artery stenoses are essential for appropriate guidance of revascularization. The aim of the study was to evaluate the relation between fractional flow reserve (FFR) and myocardial viability as assessed by gated SPECT MIBI perfusion scintigraphy in patients with previous MI undergoing elective PCI.

Methods

The study population consisted of 26 patients (mean age 55 ± 7 years; 21 male) with a previous MI and a significant coronary stenosis in a single infarct-related coronary vessel for which PCI was being performed. In all patients, FFR was evaluated before and immediately after PCI. SPECT imaging was done before and 3 ± 1 months after PCI. A region representing the MI was considered viable if MIBI uptake was ≥55% of the normal region. Improvement in perfusion after revascularization was considered achieved if perfusion abnormalities decreased by 5% or more and there was a decrease in segmental score of ≥1 in three segments in PCI-related vascular territory.

Results

Extent of perfusion abnormalities decreased from 32 ± 16% to 27 ± 19% after PCI (P < .001). In patients with myocardial viability in comparison to patients with no viability, there was significant difference in FFR before PCI (.57 ± .14 vs .76 ± .12, P = .002), despite almost the same values of diameter stenosis of infarct-related artery (63 ± 8% vs 64 ± 3%, respectively, P = .572). In addition, FFR prior to PCI was related to improvement in perfusion abnormalities after revascularization (P = .047), as well as with peak activity of creatine-kinase measured during previous MI (r = .56, P = .005).

Conclusion

Lower values of FFR before angioplasty are associated with myocardial viability and functional improvement as assessed by SPECT perfusion scintigraphy.     

Comparison of image reconstruction algorithms in myocardial perfusion scintigraphy

The purpose of this study was to compare the clinical utility of two image reconstruction algorithms in myocardial perfusion SPECT (single-photon emission computed tomography): filtered back-projection (FBP) and ordered subset expectation maximization (OSEM). A rest/stress one-day protocol with 99mTc-MIBI or tetrofosmin was performed on 102 consecutive patients who underwent coronary angiography. After SPECT data acquisition, images were reconstructed with FBP and OSEM algorithms. We assessed diagnostic performance (sensitivity, specificity and accuracy) in detecting coronary artery stenosis and evaluated regional tracer uptake with a 4-point scoring system. Although there were no significant differences in diagnostic performance between FBP and OSEM reconstruction, the OSEM method yielded higher uptake in the RCA area than the FBP method by reducing the count-loss artifact due to hepatic uptake of the tracers. In addition, regional uptake in the LCX area was significantly lower in the OSEM image than in the FBP image; this phenomenon was observed mainly in patients with coronary stenosis and/or infarction in the LCX territory. In conclusion, OSEM and FBP offered comparable diagnostic performance in stress myocardial perfusion SPECT. The OSEM method contributed to reduction of the count-loss artifact in inferior and posterior walls and to easy recognition of hypoperfusion in the LCX area.     

Detection of lesions in thallium-201 myocardial perfusion scintigraphy

Experimental studies have been made of the lesion detectability in myocardial perfusion studies using thallium-201. A series of images (AP-view) was generated using a convolution of a mathematical model of the left ventricular myocardium and an experimentally determined point spread function. Background was added. Images were simulated with 100k, 200k, and 300k counts for the complete image. Each image contained a lesion with either 0% or 50% of the normal tracer concentration. All images were interpreted by five experienced observers, independently of each other. Their interpretations were analysed using the Kolmogorov-Smirnov two sample test. The true positive fraction (TPF) was hardly affected by changes in count density. The TPF decreased significantly if the lesion tracer concentration changed from 0% to 50% of the normal myocardial tracer concentration. The decrease was independent of the count density. The false positive fraction (FPF) decreased significantly if the count density increased; no difference in FPF was found for a change in lesion tracer concentration. In addition, plots were generated with the TPF and the FPF versus lesion location and of the TPF versus lesion volume. The TPF was lowest for locations far from the camera; FPF was high for these segments. Increase of the count density mainly improved the FPF in these segments. Small lesion were more difficult to detect.     

A stochastic interpretation of thallium myocardial perfusion scintigraphy

A method is presented for the quantitative interpretation of thallium-201 myocardial perfusion studies. The data are planar images collected immediately following the stress injection, and 4 to 6 hours later. Data analysis consists of preprocessing, including thresholding of the original data, and data reduction using a variant of the circumferential profile methods. The profiles are subdivided into segments, and for each segment the difference between the norm and the actual data is computed. This difference is a quantitative symptom, whose size is assumed to be related to the probability of having the disease. The relationship between the size of the symptom in each of nine segments (three segments/view in three views) and the probability of disease is expressed in a table in which for 30 diseases (combinations of vascular lesions) the sensitivity for each of the nine symptoms is described as a Gaussian function whose average and standard deviation are computed from previous validated cases. Using an arbitrary prevalence, the post-testing probability can then be computed using Bayes' formula sequentially. The sensitivities, however, are not expressed as a binary function of the presence or absence of a symptom, but as a distribution function defined by experience. The method is sensitive for the detection of isolated left anterior descending disease (100%) and triple vessel disease (96%). When specific combinations of vascular lesions are recognized the specificity increases from 79% (when unspecified abnormalities are recognized) to 87% when left anterior descending disease or triple vessel disease is recognized.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of myocardial ischaemia as assessed with myocardial perfusion scintigraphy in patients with diabetes mellitus type 2 and mild anginal symptoms

Purpose To determine the prevalence and predictors of reversible myocardial perfusion defects, indicative of myocardial ischaemia, in patients with mild, stable anginal complaints [Canadian Cardiovascular Society classification (CCS) I–II/IV] and diabetes mellitus type 2 (T2DM). Methods A total of 329 patients with T2DM and stable, mild anginal symptoms (CCS I–II/IV) underwent myocardial perfusion scintigraphy. Perfusion images were assessed using a five-point (semi)-quantitative scoring system according to a 17-segment myocardial model. Results One-hundred and fifty-six (47%) patients showed reversible myocardial perfusion defects defined as a summed difference score of ≥3. Male gender [odds ratio (OR) 2.28, 95% CI 1.4–3.71, p=0.001], previous myocardial infarction (MI) without revascularisation (OR 3.04, 95% CI 1.28–7.24, p=0.01), and the use of two or more classes of anti-anginal medication (OR 2.36, 95% CI 1.48–3.76, p<0.001) were independent predictors for the presence of reversible defects. By contrast, lipid-lowering therapy reduced the possibility of reversible perfusion defects (OR 0.56, 95% CI 0.33–0.95, p=0.03). Conclusion Approximately half of the patients with mild, stable angina pectoris and T2DM showed evidence of myocardial ischaemia. Male gender, previous MI and the use of anti-anginal medication were positive predictors and lipid-lowering therapy was a negative predictor for the results of the scintigraphic stress test.     

Stress/rest myocardial perfusion scintigraphy in patients without significant coronary artery disease

Aim  

To define the prognostic impact of stress myocardial perfusion scintigraphy (MPS) in patients with angiographic exclusion of significant coronary artery disease.