Artifactual reverse distribution pattern in myocardial perfusion SPECT with technetium-99m sestamibi

Head-to-head comparison of diagnostic accuracy of stress-only myocardial perfusion imaging with conventional and cadmium-zinc telluride single-photon emission computed tomography in women with suspected coronary artery disease

BACKGROUND

Breast attenuation may impact the diagnostic accuracy of stress myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT). We compared the performance of conventional (C)-SPECT and cadmium-zinc-telluride (CZT)-SPECT systems in women with low-intermediate likelihood of coronary artery disease (CAD).

METHODS AND RESULTS

A total of 109 consecutive women underwent stress-optional rest MPI by both C-SPECT and CZT-SPECT. In the overall study population, a weak albeit significant correlation between total perfusion defect (TPD) measured by C-SPECT and CZT-SPECT was observed (r = 0.38, P < .001) and at Bland-Altman analysis the mean difference in TPD (C-SPECT minus CZT-SPECT) was 2.40% (P < .001). Overall concordance of semi-quantitative diagnostic performance between C-SPECT and CZT-SPECT was observed in 52 (48%) women with a κ value of 0.09. Normalcy rate was significantly higher using CZT-SPECT compared to C-SPECT (P < .001). Machine learning analysis performed through the implementation of J48 algorithm proved that CZT-SPECT has higher sensitivity, specificity, and accuracy than C-SPECT.

CONCLUSIONS

In women with low-intermediate likelihood of CAD, there is a poor concordance of diagnostic performance between C-SPECT and CZT-SPECT, and CZT-SPECT allows better normalcy rate detection compared to C-SPECT.

Reverse perfusion pattern in myocardial perfusion imaging using technetium-99m-sestamibi in patients with intermediate risk for coronary artery disease in relation to the time of acquisition and intensity of visceral uptake as artifactual causes

OBJECTIVE

With respect to the equivocal value of the reverse perfusion pattern (RPP) in technetium-99m (Tc)-sestamibi myocardial perfusion imaging, a study was carried out to evaluate this pattern in association with the presence or absence of coronary artery disease (CAD) and other underlying factors, mainly the time of acquisition and the presence of intense visceral uptake.

PATIENTS AND METHODS

We prospectively studied 102 patients with a moderate risk of CAD (41 men and 61 women, mean age: 56.5±9.2 years) without a previous history of documented CAD, myocardial infarction, or revascularization. Myocardial perfusion imaging was performed using a 2-day dual-phase protocol with the stress and rest images, each obtained 15, 120, and 180 min after an injection of 666-814 MBq Tc-MIBI. According to the time of image acquisition, the following five protocols were defined, A: 15/15 min, B: 15/180 min, C: 180/180 min, D: 180/15 min, and E: 120/120 min for stress/rest images, respectively.

RESULTS

The odds of RPP were higher in the cases with more intense infradiaphragmatic visceral uptake on rest-phase images of the protocols A and D (odds ratios=1.2-7.8 and 1.2-7.5, respectively). Our results showed that RPP is related to incorrect normalization. Also, diabetes, sex, and CAD did not correlate with RPP.

CONCLUSION

This study found no relationship between RPP and CAD, diabetes mellitus, and sex; however, an association was found between RPP and incorrect normalization because of the variation of visceral uptake intensity in relation to the time of acquisition at stress and rest phases favoring the artifactual base of this pattern.

Myocardial Injury without Electrocardiographic Changes after a Suicide Attempt by an Overdose of Glimepiride and Zolpidem: A Case Report and Literature Review

A 40-year-old diabetic man was admitted to our hospital for poor glycemic control. During hospitalization, he took 42 mg glimepiride and 50 mg zolpidem as a suicide attempt. The following day, the creatine kinase-MB fraction and troponin I levels were elevated to 112 IU/L and 8.77 ng/mL, respectively, without any electrocardiographic abnormalities. The patient recovered completely without any complications. Four weeks later, coronary computed tomography angiography and myocardial perfusion scintigraphy revealed moderate one-vessel coronary disease without the evidence of myocardial ischemia or old infarction. Cardiac-specific markers must be considered in sulfonylurea-induced hypoglycemic patients, particularly when the patient is unconscious and does not exhibit any clinical manifestations.

The Role of Myocardial Perfusion Gated SPECT Study in Women with Coronary Artery Disease: A Correlative Study

Objective: We aimed to evaluate the role of gated myocardial perfusion SPECT (MPS) and to investigate whether only the invasive coronary angiography (CAG) is sufficient in the diagnosis of the coronary artery disease (CAD) in women.

Material and Methods: Sixty-four women (62±10 years) with known CAD were included in this study. They had echocardiography (ECHO), stress/rest gated MPS and invasive CAG. Coronary stenosis as of > 50 % in invasive CAG was accepted as significant. Gated MPS data were compared with invasive CAG and ECHO.

Results: Invasive CAG results were abnormal in 34 patients, and normal in 30 cases. Myocardial ischemia was detected by gated MPS in 22/ 30 cases with normal invasive CAG, 6 had mild coronary stenosis in major coronary arteries ranging from 30% to 50% in invasive CAG. 16/ 22 women were diagnosed as metabolic syndrome according to MetSend Diagnostic Criteria and only 8 of 30 patients with normal invasive CAG had false positive MPS data on the reevaluation by a nuclear cardiologist.

Conclusion: We think that invasive coronary angiography method is not sufficient alone in the diagnosis of CAD in women. Gated MPS study is recommended to achieve the final decision for myocardial ischemia in the cases with CAD and raw data must always be evaluated to avoid attenuation artifacts.

Conflict of interest:None declared.

Paradoxical scintigraphic pattern in regions with myocardial necrosis on myocardial perfusion gated SPECT with ⁹⁹mTc-tetrofosmin

OBJECTIVES

To assess the significance of a paradoxical pattern (PP) (greater tracer uptake during stress than at rest) on gated myocardial perfusion SPECT in myocardial regions with myocardial necrosis.

METHODS

A review of 1,764 consecutive stress-rest myocardial perfusion SPECT studies in patients with prior myocardial infarction (MI) was conducted. Of these, 117 patients (6.6%) with a PP corresponding to a region with myocardial necrosis were identified. An assessment of perfusion, contractility, wall thickening, scintigraphic criteria for viability, and the characteristics of the culprit artery in regions with a PP was performed.

RESULTS

Of the 160 regions with necrosis, 125 (75%) had a PP: 67 in the anterior region and 58 in the inferior-lateral region. In the PP group, the average tracer activity of defects during stress was significantly higher than at rest (P < .0001). Ninety-three (86.6%) out of 110 PP segments without scintigraphic criteria of viability at rest met viability criteria on stress imaging. The artery supplying regions with a PP was patent in 88% of cases. In the remaining patients it was occluded, although collateral circulation was always present.

CONCLUSIONS

In scintigraphic segments corresponding to regions with infarction and PP, a mixture of viable and well perfused myocardium was observed. In most cases, the vessel that supplied the region with PP was either patent, or when the artery was occluded, there was evident collateral circulation.

Investigation of the mechanism of reverse redistribution in thallium-201 myocardial perfusion scintigraphy in patients with suspicion for coronary artery spasm

BACKGROUND

Reverse redistribution (RR) is one of the features on myocardial perfusion scintigraphy (MPS) in patients with coronary artery spasm (CAS). This study was aimed to explore the mechanism of RR in patients with suspicion for CAS.

METHODS AND RESULTS

Thirty patients with RR and suspicion for CAS but without coronary artery stenosis (RR group) and 32 control patients without RR (control group) underwent coronary angiography before and after a dipyridamole administration. Coronary blood flow velocity and myocardial perfusion, as determined by corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) and TIMI myocardial perfusion grade (TMPG), were measured. Coronary angiography showed significantly slower blood flow velocity [CTFC (37 ± 6) frame vs (29 ± 7) frame, P < .01] and lower myocardial perfusion [TMPG (2.08 ± 0.38) grade vs (2.55 ± 0.33) grade, P < .05] in RR-related arteries than in RR-unrelated arteries in the RR group. But, there was no significant difference among different coronary artery branches in the control group. After the injection of dipyridamole, CTFC decreased and TMPG increased in the RR group. The decline in CTFC and the increase in TMPG in RR-related arteries were more significant than those in RR-unrelated ones (28% vs 14% and 45% vs 16%, respectively; both P < .01). The endothelin-1/nitric oxide (NO) ratio was significantly higher in the RR group than in the control group before the injection of dipyridamole (2.79 ± 0.37 vs 1.70 ± 0.19, P < .01). After the injection of dipyridamole, the ratio went down in both groups, but the decline was statistically significant in the RR group (2.42 ± 0.33, P < .05) but not in the control group (1.42 ± 0.19, P < .05). Pearson correlation analysis showed that there was a positive correlation between summed rest scores on MPS and the endothelin-1/NO ratio (r = 0.853, P = .000) as well as CTFC (r = 0.808, P = .000) before the injection of dipyridamole in the RR group.

CONCLUSION

Patients with suspicion for CAS may exhibit a mild spasm of RR-related arteries and corresponding microvasculature and a significant imbalance of coronary blood flow velocity and myocardial perfusion at rest between RR-related and RR-unrelated areas. This is overcome by stress-induced hyperemic flow increases and which may account for RR on MPS.

Sex-specific approach to gated SPECT volumetric analysis after stress and at rest to detect high-risk coronary artery disease

OBJECTIVES

To determine the role of quantitative analysis of poststress and resting left ventricular function using sex-specific criteria to detect high-risk coronary artery disease (CAD) as defined by the Duke CAD Prognostic Index.

METHODS AND RESULTS

Stress technetium-99m-sestamibi-gated single-photon emission computed tomography and coronary angiography were performed in 407 consecutive patients (300 men, 107 women) with suspected CAD. The cut-off point for high-risk CAD was defined as a Duke CAD Prognostic Index of 42. The stress-to-rest ratios of end-diastolic volume (rEDV) and end-systolic volume (rESV) were analyzed. In 102 patients with high-risk CAD, the summed difference scores, rEDV and rESV, were greater than in 305 patients with low-risk to intermediate-risk CAD. The receiver operating characteristic curves revealed that the optimal cut-off points for rEDV and rESV to detect high-risk CAD were 1.10 and 1.11, respectively. Sex-specific rEDV was 1.08 in men, 1.11 in women, and sex-specific rESV was 1.09 in men and 1.20 in women. Multivariate discriminant analysis showed that the combination of sex-specific rEDV, sex-specific rESV, and summed difference scores greater than or equal to 8 best identified high-risk CAD, with a sensitivity of 75% and specificity of 76%.

CONCLUSION

The addition of a sex-specific approach to left ventricular functional analysis using gated single-photon emission computed tomography on conventional perfusion analysis, may help better identify patients with high-risk CAD as defined by the Duke CAD Prognostic Index.

Noninvasive assessment of coronary anatomy and myocardial perfusion: going toward an integrated imaging approach

Many noninvasive imaging techniques are available for the evaluation of patients with known or suspected chronic coronary artery disease. Among these, computed tomography-based techniques allow the quantification of coronary atherosclerotic calcium and noninvasive imaging of coronary arteries, whereas nuclear cardiology is the most widely used noninvasive approach for the assessment of myocardial perfusion. The available single-photon emission computed tomography flow agents are characterized by a cardiac uptake proportional to myocardial blood flow. In addition, different positron emission tomography tracers may be used for the quantitative measurement of myocardial blood flow and coronary flow reserve. Extensive research is currently being performed in the development of noninvasive coronary angiography and myocardial perfusion imaging using cardiac magnetic resonance. Finally, new multimodality imaging systems have been recently developed, bringing together anatomical and functional information. This review sought to provide a description of the relative merits of noninvasive imaging techniques in the assessment of coronary anatomy and myocardial perfusion in patients with known or suspected coronary artery disease.

Method for coronary angiography in morbidly obese patients

Cardiac catheterization in morbidly obese patients is difficult. In addition to problems regarding vascular access and radiographic penetration of the chest, the engineering parameters and physical limitations of the table and its supporting structures may limit these patients' ability to undergo clinically indicated coronary angiography. We describe a method for cardiac catheterization in which much of the obese patient's body weight is supported on a stretcher placed at right angles to the catheterization table, with only the thorax on the table under the image intensifier. Using this method, five consecutive successful diagnostic procedures and one coronary stent procedure have been performed without complication. Limitations of this procedure include inability to achieve the normal variety of angiographic views due to constraints on image intensifier rotation and skew.

“W-shaped” volume curve with gated myocardial perfusion single photon emission computed tomography

OBJECTIVES

Gating errors (GEs) with ECG gated myocardial SPECT (G-SPECT) may occur irrespective of the presence or absence of arrhythmias. We evaluated the impact of GEs on both reconstructed tomograms and left ventricular ejection fraction (LVEF) derived from G-SPECT, and searched for clues to identify these errors.

METHODS

We studied 2 GE patients, 10 normal subjects (NLs), and 10 atrial fibrillation patients. Stress technetium-99m sestamibi G-SPECT was performed. Left ventricular (LV) contraction was evaluated in the beating slices. LVEF was calculated with G-SPECT using QGS (Cedars-Sinai, Los Angels) and p-FAST (Sapporo Medical University, Japan), and compared with that obtained by echocardiography (ECHO). LV volume curves were created by QGS and p-FAST. The heart rates (HRs) were calculated from the acquired images, and compared with their resting HRs. The mean count density of the myocardium was measured and time-activity curves were created.

RESULTS

In patients with GEs, bi-phasic LV contraction was demonstrated with fading-out towards end-diastole. G-SPECT underestimated LVEF compared to ECHO by 10% or more. The volume curves appeared "W-shaped." The HRs from the images were slower than the resting HRs. The count density decrement from frame #1 to #8 was larger than that of NLs. The time-activity curves were different in shape from those of NLs.

CONCLUSIONS

G-SPECT underestimates LVEF in patients with GEs. These errors can be identified with a combination of visual inspection of beating slices, time-volume curves, and time-activity curves. Monitoring the HR is a clue for anticipating and avoiding these errors.

Cardiac imaging using nuclear medicine and postitron emission tomography

This article concentrates on specific issues that are of current interest in mainstream nuclear cardiology. These include developments in myocardial perfusion technique, the potential diagnostic benefits of ECG-gating and attenuation correction, nuclear imaging in the diagnosis of hibernating myocardium, and the cost-effectiveness of perfusion imaging in patients with suspected angina.