ECG-gated Single Photon Emission Computed Tomography Research Articles

Prognostic risk stratification based on left ventricular mechanical dyssynchrony in patients at low or intermediate risk of major cardiac events using the J-ACCESS risk model.

There have been no reports on prognostic prediction and risk stratification based on stress phase bandwidth (SPBW), or a left ventricular (LV) mechanical dyssynchrony index, in patients with known or suspected stable coronary artery disease (CAD) at low or intermediate risk of major cardiac events (MCEs) using the J-ACCESS risk model. We retrospectively investigated 4,996 consecutive patients with known or suspected CAD who underwent rest 201Tl and stress 99mTc-tetrofosmin electrocardiogram (ECG)-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) and followed up for 3 years to confirm their prognosis. MCE risk over 3 years was estimated using an equation based on that used in the J-ACCESS study. The composite endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction (MI), and severe heart failure requiring hospitalization. SPBW was calculated by phase analysis with the Heart Risk View-F software and its normal upper limit was set to 38°. Based on the estimated 3-year incidence of MCEs obtained from the J-ACCESS risk model, 4,123 of the 4,996 consecutive patients were classified as low (n = 2,653) or intermediate risk (n = 1,470) and they were analyzed for follow-up. During the follow-up, 153 patients experienced MCEs: cardiac death (n = 38), non-fatal MI (n = 45), and severe heart failure (n = 70). The results of the multivariate analysis showed age, estimated glomerular filtration rate (eGFR), stress LV ejection fraction, and stress SPBW to be independent predictors of MCEs. The actual 3-year MCE rate in patients at intermediate risk was significantly higher than in those at low risk (6.7% vs. 2.1%, P < 0.0001). However, the actual 3-year MCE rate in patients with abnormal SPBW (> 38°) was 4.0% and 9.2% in low- and intermediate-risk patients, respectively, which corresponded to intermediate and high risk. Kaplan-Meier analysis also showed significant risk stratification by normal SPBW values for both low- and intermediate-risk patients. LV mechanical dyssynchrony assessed with ECG-gated SPECT MPI is useful for risk stratification of known or suspected stable CAD patients at low or intermediate risk of MCEs and may help identify higher risk patients who could not be identified as being at risk based on J-ACCESS risk assessment.

Prognostic Value of Left Ventricular Dyssynchrony Assessed with Nuclear Cardiology in Patients with Known or Suspected Stable Coronary Artery Disease with Preserved Left Ventricular Ejection Fraction.

Left ventricular (LV) mechanical dyssynchrony assessed with phase analysis of electrocardiogram (ECG) -gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is useful for predicting major cardiac events (MCEs) in patients with cardiac dysfunction. However, there is no report on its usefulness in Japanese patients with known or suspected stable coronary artery disease (CAD) with preserved LV ejection fraction (LVEF).We retrospectively investigated 3,374 consecutive patients with known or suspected CAD who underwent rest 201Tl and stress 99mTc-tetrofosmin ECG-gated SPECT MPI and had preserved LVEF (≥ 45%), and followed them up to confirm their prognosis for three years. The composite endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction (MI), unstable angina pectoris, and severe heart failure requiring hospitalization. LV mechanical dyssynchrony was evaluated with phase analysis with the Heart Risk View-F software to obtain the phase bandwidth and standard deviation.During the follow-up, 179 patients experienced MCEs: cardiac death (n = 42); non-fatal MI (n = 34); unstable angina pectoris (n = 54); and severe heart failure (n = 49). Results of the multivariate analysis showed age, a history of MI, diabetes mellitus, summed stress score, and stress phase bandwidth to be independent predictors for MCEs. In Kaplan-Meier analysis, prognoses were significantly stratified with the tertiles of stress phase bandwidth.LV mechanical dyssynchrony assessed with ECG-gated SPECT MPI is useful for predicting a prognosis and stratifying the risk of MCEs in Japanese patients with known or suspected stable CAD with preserved LVEF.

The impact of frame numbers on cardiac ECG-gated SPECT images with interpolated extra frames using echocardiography.

Background: Cardiac echocardiography and cardiac ECG-gated single-photon emission computed tomography (SPECT) are the most common modalities for left ventricle (LV) volumes and function assessment. The temporal resolution of SPECT images is limited and an ECG provides better temporal resolution. This study investigates the impact of frame numbers on images in terms of qualitative and quantitative assessments. Methods: In this study, 5 patients underwent echocardiography and cardiac ECG-gated SPECT imaging, and 5 standard views of the LV were recorded to determine LV walls boundaries and volumes. Also, 2 original images with 8 frames and 16 frames per cardiac cycle were recorded simultaneously in a single gantry orbit. Using the data extracted from the LV model, 8 extra new frames were created with interpolation between existing frames of the original 8-frame image. Three series of images (8 and 16 original and 16 interpolated) were reconstructed separately. LV volumes and ejection fraction (EF) were calculated using Quantitative Gated SPECT (QGS) software. Results: Compared to the original 8-frame gating, original 16-frame gated images resulted in larger end-diastole volume (EDV) (mean ± SD: 68.6 ± 27.11 mL vs 66.2±25.41 mL, p<0.001), smaller end-systole volume (ESV) (mean ± SD: 24.6±8.7 mL vs 26±7.3 mL, p<0.001), and higher EF (64% vs 60.2%, p<0.001). The results for the interpolated series were also different from the original images (closer to the original 16-frame series rather than 8-frame). Conclusion: Changing the frame number from 8 to 16 in cardiac ECG-gated SPECT images caused a significant change in LV volumes and EF. Frame interpolation with sophisticated algorithms can be used to improve the temporal resolution of SPECT images.

Time-modified OSEM algorithm for more robust assessment of left ventricular dyssynchrony with phase analysis in ECG-gated myocardial perfusion SPECT

BackgroundIn ordered subsets expectation maximization (OSEM) reconstruction of electrocardiography (ECG)-gated myocardial perfusion single-photon emission computed tomography (SPECT), it is often assumed that the image acquisition time is constant for each projection angle and ECG bin. Due to heart rate variability (HRV), this assumption may lead to errors in quantification of left ventricular mechanical dyssynchrony with phase analysis. We hypothesize that a time-modified OSEM (TOSEM) algorithm provides more robust results.MethodsList-mode data of 44 patients were acquired with a dual-detector SPECT/CT system and binned to eight ECG bins. First, activity ratio (AR)—the ratio of total activity in the last OSEM-reconstructed ECG bin and first five ECG bins—was computed, as well as standard deviation SDR-R of the accepted R–R intervals; their association was evaluated with Pearson correlation analysis. Subsequently, patients whose AR was higher than 90% were selected, and their list-mode data were rebinned by omitting a part of the acquired counts to yield AR values of 90%, 80%, 70%, 60% and 50%. These data sets were reconstructed with OSEM and TOSEM algorithms, and phase analysis was performed. Reliability of both algorithms was assessed by computing concordance correlation coefficients (CCCs) between the 90% data and data corresponding to lower AR values. Finally, phase analysis results assessed from OSEM- and TOSEM-reconstructed images were compared.ResultsA strong negative correlation (r = -0.749) was found between SDR-R and AR. As AR decreased, phase analysis parameters obtained from OSEM images decreased significantly. On the contrary, reduction of AR had no significant effect on phase analysis parameters obtained from TOSEM images (CCC > 0.88). The magnitude of difference between OSEM and TOSEM results increased as AR decreased.ConclusionsTOSEM algorithm minimizes the HRV-related error and can be used to provide more robust phase analysis results.

Diagnostic value of peak filling rate derived from ECG-gated myocardial perfusion SPECT for detecting myocardial ischaemia in patients with non-obstructive coronary artery disease

Background: Left ventricular (LV) diastolic dysfunction represents an earlier step of the ischaemic cascade. We tested the hypothesis that the index of LV diastolic function from electrocardiogram (ECG)-gated single photon emission computed tomography (SPECT) is useful in detecting myocardial ischaemia in patients with non-obstructive coronary artery disease (CAD).Methods: One-hundred-ten patients with non-obstructive CAD and summed redistribution score of zero were enrolled. Summed difference score (SDS) of ≥2 was considered as the presence of myocardial ischaemia. Peak filling rate (PFR) defined as the maximum dV/dt divided by LV end-diastolic volume was obtained as the index of LV diastolic function.Results: Of 110 patients with non-obstructive CAD, 51 patients had myocardial ischaemia. SDSs in patients with myocardial ischaemia and those without were 3.5 ± 1.8 and 0.4 ± 0.5, respectively (p < 0.001). PFRs after stress (r = −0.22, p = 0.02) and at redistribution (r = −0.24, p = 0.01) were inversely correlated with SDS. Multivariate logistic regression analysis showed that PFR at redistribution was an independent predictor of the presence of myocardial ischaemia in patients with non-obstructive CAD (odds ratio: 0.15, 95% confidence interval: 0.04–0.51, p = 0.002).Conclusion: Our data suggest that PFR, the index of LV diastolic function from ECG-gated SPECT, helps to find myocardial ischaemia in patients with non-obstructive CAD.

Implications of electrocardiographic frontal QRS axis on left ventricular diastolic parameters derived from electrocardiogram-gated myocardial perfusion single photon emission computed tomography

Current electrocardiographic (ECG) machines report various variables including frontal QRS axis automatically. We tested the hypothesis that QRS axis is associated with left ventricular (LV) diastolic parameters derived from ECG-gated myocardial perfusion single photon emission computed tomography (SPECT) independent of myocardial ischemia. Ninety-three patients with preserved LV ejection fraction and no evidence of myocardial ischemia were enrolled based on ECG-gated SPECT. Peak filling rate (PFR), one-third mean filling rate (1/3 MFR) and time to peak filling (TTPF) were obtained as LV diastolic parameters. There were 82 male and 11 female patients with a mean age of 69 ± 9years. QRS axis ranged from - 40° to 85° (36° ± 31°). QRS axis was correlated with PFR (r = 0.28, p < 0.01), 1/3 MFR (r = 0.25, p = 0.02) and TTPF (r = - 0.21, p = 0.04). QRS axis was also correlated with age (r = - 0.23, p = 0.03), body mass index (BMI) (r = - 0.36, p < 0.01) and LV mass index (LVMI) (r = - 0.27, p < 0.01). Linear regression analysis showed that QRS axis was associated with PFR, 1/3 MFR and TTPF for LV diastolic function, but was not associated with these LV diastolic parameters after adjustment of various confounders. Our data suggest that QRS axis depends on age, BMI or LVMI, and serves as a surrogate marker of LV diastolic function.

Prevalence and predictors of left intraventricular dyssynchrony determined by phase analysis in patients undergoing gatedSPECT myocardial perfusion imaging.

Left ventricular dyssynchrony (LVD) is an independent predictor of adverse cardiovascular events, death, and progression to heart failure. Myocardial perfusion imaging (MPI) with ECG-gated single-photon emission computed tomography (SPECT) can be used to diagnose LVD rapidly and automatically using phase analysis (PA). The objective of this study was to evaluate the prevalence and predictors of LVD in patients undergoing MPI. Clinical, electrocardiographic, and scintigraphic data from 1000 patients who underwent MPI with ECG-gated SPECT over a period of 1year were analyzed retrospectively. TheEmoryCardiac Toolboxsoftware was used for PA, and LVD was diagnosed based on the following criteria: standard deviation of LV phase distribution ≥43° and/or phase histogram ≥140° in the resting and/or stress phase of the examination. Several variables were evaluated using univariate and multivariate analyses. The prevalence of LVD in the study population was 6.5%, and the average age was 63.6±12years. The variables significantly associated with LVD were male gender, obesity, hypertension, diabetes, dyslipidemia, coronary artery disease (CAD), QRS interval ≥120ms, LV dysfunction, and myocardial perfusion defects (especially fixed defects) on MPI. Although the PA parameters were greater at rest, both phases could be used for diagnosis. Multivariate analysis revealed that the variables significantly associated with LVD were male sex, obesity, history of CAD, and QRS interval ≥120ms. The overall prevalence of LVD was 6.5% in patients undergoing MPI in this study, and it reached 42% in the presence of certain risk factors.

The impact of hypertension on diastolic left ventricular function, evaluated by quantitative ECG-gated myocardial perfusion SPECT

BackgroundAbnormality of left ventricular (LV) diastolic function is frequently the earliest indicator of LV dysfunction in many diseases, including coronary artery disease (CAD), and hypertension. Electrocardiography (ECG)-gated technetium (Tc)-99m tetrofosmin single-photon emission computed tomography (SPECT) has been reported to be a useful method for evaluation of LV function. ObjectivesThe purpose of this study was to assess the impact of hypertension on diastolic left ventricular function using ECG-gated Tc-99m tetrofosmin SPECT. MethodsThirty consecutive patients with normal exercise myocardial perfusion and normal LV systolic function, were studied out of 233 patients underwent ECG-gated Tc-99m tetrofosmin SPECT at our institution between January 2012 and December 2013. Patients were divided into two groups according to the presence or absence of systemic hypertension (blood pressure ⩾140/90mm Hg on ⩾3 measurements or treatment with antihypertensive medication). Parameters of diastolic LV function were assessed. ResultsOf the studied 30 patients, 19/30 (63%) had hypertension. There was no difference with respect to age, gender, LV end-diastolic volume (EDV), LV end-systolic volume (ESV), and LV ejection fraction values obtained by quantitative gated SPECT between patients with and without hypertension. The first-third mean filling rate (1/3 MFR), peak filling rate (PFR) of patients with hypertension (1.22±0.38, 2.83±1.10 EDV/s) were lower than those of patients without hypertension (1.54±0.30, 2.90±0.35 EDV/s), and the time to peak filling (TTPF) of patients with hypertension (199.42±68.34ms) was higher than TTPF of patients without hypertension (164.90±36.39ms). ConclusionsQuantitative ECG-gated Tc-99m tetrofosmin SPECT reveals that hypertensive patients with preserved global LV systolic function may have significant changes in diastolic LV function. Gated myocardial perfusion SPECT reports are always lacking in these changes in diastolic function. We recommend inclusion of such changes in diastolic function in gated myocardial perfusion SPECT reports that can help in proper management of hypertensive patients.

Heart Failure and ECG-gated Single-photon Emission Computed Tomography

First of all, myocardial perfusion single-photon emission computed tomography (SPECT) will be used for the differentiation of ischemic cardiomyopathy and non-ischemic cardiomyopathy (DCM). Basically, non-ischemic cardiomyopathy shows essentially normal perfusion and global hypokinesis of the left ventricle with an impaired ejection fraction. ECG-gated SPECT calculates regional wall motion (mm), wall thickening (%) and time to maximum thickening (TTMT: msec) with QGS software. The patients with DCM showed higher maximum difference of TTMT (deltaTTMT) and coefficient of variation of TTMT (CVTTMT) than those in normal control subjects (16.4 vs 7.8, p<0.0001 and 206 vs 103msec, p<0.0001).

Quantitation of myocardial blood flow and myocardial flow reserve with 99mTc-sestamibi dynamic SPECT/CT to enhance detection of coronary artery disease.

Conventional dual-head single photon emission computed tomography (SPECT)/CT systems capable of fast dynamic SPECT (DySPECT) imaging have a potential for flow quantitation. This study introduced a new method to quantify myocardial blood flow (MBF) and myocardial flow reserve (MFR) with DySPECT scan and evaluated the diagnostic performance of detecting coronary artery disease (CAD) compared with perfusion using invasive coronary angiography (CAG) as the reference standard. This study included 21 patients with suspected or known CAD who had received DySPECT, ECG-gated SPECT (GSPECT), and CAG (13 with ≥ 50% stenosis in any vessel; non-CAD group: 8 with patent arteries or < 50% stenosis). DySPECT and GSPECT scans were performed on a widely used dual-head SPECT/CT scanner. The DySPECT imaging protocol utilized 12-min multiple back-and-forth gantry rotations during injections of (99m)Tc-sestamibi (MIBI) tracer at rest or dipyridamole-stress stages. DySPECT images were reconstructed with full physical corrections and converted to the physical unit of becquerels per milliliter. Stress MBF (SMBF), rest MBF (RMBF), and MFR were quantified by a one-tissue compartment flow model using time-activity curves derived from DySPECT images. Perfusion images were processed for GSPECT scan and interpreted to obtain summed stress score (SSS) and summed difference score (SDS). Receiver-operating characteristic (ROC) analyses were conducted to evaluate the diagnostic performance of flow and perfusion. Using the criteria of ≥ 50% stenosis as positive CAD, areas under the ROC curve (AUCs) of flow assessment were overall significantly greater than those of perfusion. For patient-based analysis, AUCs for MFR, SMBF, SSS, and SDS were 0.91 ± 0.07, 0.86 ± 0.09, 0.64 ± 0.12, and 0.59 ± 0.13. For vessel-based analysis, AUCs for MFR, SMBF, SSS, and SDS were 0.81 ± 0.05, 0.76 ± 0.06, 0.62 ± 0.07, and 0.56 ± 0.08, respectively. The preliminary data suggest that MBF quantitation with a conventional SPECT/CT system and the flow quantitation method is a clinically effective approach to enhance CAD detection.

Comparison of Sulfur Hexafluoride Microbubble (SonoVue)-Enhanced Myocardial Contrast Echocardiography With Gated Single-Photon Emission Computed Tomography for Detection of Significant Coronary Artery Disease: A Large European Multicenter Study

The purpose of this study was to compare sulfur hexafluoride microbubble (SonoVue)-enhanced myocardial contrast echocardiography (MCE) with single-photon emission computed tomography (SPECT) relative to coronary angiography (CA) for assessment of coronary artery disease (CAD).Small-scale studies have shown that myocardial perfusion assessed by SonoVue-enhanced MCE is a viable alternative to SPECT for CAD assessment. However, large multicenter studies are lacking.Patients referred for myocardial ischemia testing at 34 centers underwent rest/vasodilator SonoVue-enhanced flash-replenishment MCE, standard (99m)Tc-labeled electrocardiography-gated SPECT, and quantitative CA within 1 month. Myocardial ischemia assessments by 3 independent, blinded readers for MCE and 3 readers for SPECT were collapsed into 1 diagnosis per patient per technique and were compared to CA (reference standard) read by 1 independent blinded reader.Of 628 enrolled patients who received SonoVue (71% males; mean age: 64 years; >1 cardiovascular [CV] risk factor in 99% of patients) 516 patients underwent all 3 examinations, of whom 161 (31.2%) had ≥70% stenosis (131 had single-vessel disease [SVD]; 30 had multivessel disease), and 310 (60.1%) had ≥50% stenosis. Higher sensitivity was obtained with MCE than with SPECT (75.2% vs. 49.1%, respectively; p < 0.0001), although specificity was lower (52.4% vs. 80.6%, respectively; p < 0.0001) for ≥70% stenosis. Similar findings were obtained for patients with ≥50% stenosis. Sensitivity levels for detection of SVD and proximal disease for ≥70% stenosis were higher for MCE (72.5% vs. 42.7%, respectively; p < 0.0001; 80% vs. 58%, respectively; p = 0.005, respectively).SonoVue-enhanced MCE demonstrated superior sensitivity but lower specificity for detection of CAD compared to SPECT in a population with a high incidence of CV risk factors and intermediate-high prevalence of CAD. (A phase III study to compare SonoVue® enhanced myocardial echocardiography [MCE] to single photon emission computerized tomography [ECG-GATED SPECT], at rest and at peak of low-dose Dipyridamole stress test, in the assessment of significant coronary artery disease [CAD] in patients with suspect or known CAD using Coronary Angiography as Gold Standard-SonoVue MCE vs SPECT; EUCTR2007-003492-39-GR).

Impaired renal function is a major determinant of left ventricular diastolic dysfunction: assessment by stress myocardial perfusion imaging

ObjectiveRelationships between myocardial scintigraphic parameters and renal function have not been fully determined. We investigated correlations between estimated glomerular filtration rate (eGFR) and left ventricular (LV) diastolic function using stress electrocardiographic (ECG)-gated myocardial single photon emission computed tomography (SPECT).MethodsWe enrolled 136 consecutive patients with suspected coronary artery disease (CAD) who were assessed using technetium-99m stress ECG-gated myocardial SPECT. We evaluated SPECT images using 17-segment defect scores graded on a 5-point scale, summed stress score, summed rest score and summed difference score (SDS). The parameters for assessing LV diastolic function were peak filling rate (PFR), 1/3 mean filling rate and time to peak filling. The CAD was defined as SDS ≥2. Chronic kidney disease (CKD) was defined as eGFR <60 mL/min/1.73 m2. Patients were assigned to the following four groups (no CAD/no CKD: control group, n = 68; CAD/no CKD: CAD group, n = 24; no CAD/CKD: CKD group, n = 34; CAD/CKD: CAD + CKD group, n = 10).ResultsThe PFR was significantly impaired after stress in the CKD and CAD + CKD groups compared with controls (p < 0.001 for both). Furthermore, PFR at rest positively correlated with eGFR (r = 0.29, p < 0.001) and inversely correlated with SDS (r = −0.18, p < 0.05). Multivariate stepwise regression analysis independently associated eGFR with PFR (β coefficient = 0.260, p = 0.002).ConclusionsOur data suggest that impaired renal function is a significant determinant of LV diastolic dysfunction in patients with suspected CAD.

Reverse blood flow-glucose metabolism mismatch indicates preserved oxygen metabolism in patients with revascularised myocardial infarction

Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) has been reported to be unreliable for identifying viable myocardium in acute myocardial infarction (AMI), especially in areas with discordance in myocardial blood flow (MBF) and glucose metabolism. In myocardium with decreased FDG uptake but preserved MBF, referred to as exhibiting reverse mismatch, myocardial viability remains controversial and little is known about the metabolic state. The aims of this study were to clarify substrate use and to estimate myocardial viability in infarct areas exhibiting reverse mismatch. Eighteen AMI patients with successful revascularisation were included in this study. Two weeks after onset, (11)C-acetate and (18)F-FDG PET were performed to evaluate regional oxygen consumption (k mono), MBF and glucose metabolism. Free fatty acid (FFA) metabolism was evaluated with (123)I-15-(p-iodophenyl)-3-(R, S)-methylpentadecanoic acid (BMIPP) single photon emission computed tomography (SPECT). To assess wall motion, movement in left ventricular endocardial surface was calculated using ECG-gated (99m)Tc-tetrofosmin SPECT. The %k mono values in reverse mismatch segments (52.6 ± 13.6%) were not significantly different from those in non-infarct segments (60.4 ± 12.8%, p = 0.071) and normal match segments (preserved MBF and FDG uptake) (58.6 ± 11.6%, p = 0.396), although regional wall motion was more severely impaired (3.06 ± 2.52 mm vs 6.78 ± 3.17 mm, p < 0.0001, and vs 5.30 ± 2.33 mm, p = 0.042, respectively). Compared to segments with reduced match (reduced MBF and FDG uptake), %k mono and %BMIPP uptake were significantly higher in reverse mismatch segments (52.6 ± 13.6% vs 37.4 ± 8.9%, p = 0.0002, and 58.8 ± 10.6% vs 40.2 ± 10.7%, p < 0.0001). Reverse mismatch in reperfused AMI patients, high oxygen consumption and FFA metabolism were observed despite decreased glucose metabolism. We conclude that reverse mismatch indicated the myocardium with early restoration of MBF and aerobic FFA metabolism.

Association between left ventricular mechanical dyssynchrony with myocardial perfusion and functional parameters in patients with left bundle branch block

ObjectiveTo identify predictors of left ventricular mechanical dyssynchrony (LVMD) in patients with known left bundle branch block (LBBB) using gated single-photon emission computed tomography (SPECT) phase analysis. Methods81 patients (74% male, 70 ± 10 years) with LBBB and suspected or known coronary artery disease underwent ECG-gated myocardial perfusion SPECT. LV perfusion and functional parameters were measured, and phase analysis was performed to quantify LV-dyssynchrony. Results35/81 patients (42%) had prior myocardial infarction (MI), and the mean left ventricular ejection fraction (LVEF) was 49% ± 16%. LVMD was present in 58/81 (72%) patients. The summed thickening score (STS) (P < .001; odds ratio 1.22) emerged as independent predictor for the presence of LVMD in a multivariate regression model. In addition, prior MI, low LVEF, summed stress score, summed rest score, summed motion score, and LAD rest extent were identified as predictors of LVMD in a univariate model. Clinical baseline characteristics, cardiac risk factors, and QRS duration (P = .051) had no influence on the presence of LVMD. ConclusionIn patients with LBBB, the occurrence of LVMD as assessed by gated SPECT phase analysis is mainly influenced by reduced myocardial contractility as expressed by the STS. Proper discrimination between LVMD arising from known electrical conduction delay as opposed to areas of MI causing reduced regional contractility seems to be mandatory for therapy planning in patients with LVMD.

Assessment of Left Ventricular Systolic and Diastolic Function Using ECG-Gated Technetium-99m Tetrofosmin Myocardial Perfusion SPECT

Because left ventricular (LV) diastolic dysfunction is frequently the earliest indicator of LV dysfunction in patients with heart failure, the estimation of LV diastolic function is very important. On the other hand, electrocardiography (ECG)-gated technetium (Tc) -99m tetrofosmin single-photon emission computed tomography (SPECT) has been reported to be a useful method for evaluation of LV function. The objective of this study was to examine the usefulness of ECG-gated Tc-99m tetrofosmin SPECT in terms of estimation of cardiac diastolic function. Consecutive 145 patients underwent an ECG-gated Tc-99m tetrofosmin SPECT to estimate systolic and diastolic LV function, and were compared with those evaluated by ultrasound echocardiography (UCG). LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction values obtained by quantitative gated SPECT (QGS) showed significant positive linear correlations with those obtained by UCG. All 145 patients were classified into 3 groups according to diastolic function estimated by UCG. The first-third mean filling rate (1/3 MFR) and peak filling rate (PFR) that revealed the LV diastolic function of the group B (normal systolic function and mild diastolic dysfunction) patients (1.01 ± 0.35, 1.85 ± 0.57) were both significantly lower than those of the group A (normal systolic and diastolic function) patients (1.43 ± 0.37, 2.43 ± 0.56). The 1/3 MFR and PFR of the group C (moderate ~ severe systolic and diastolic dysfunction) patients (0.47 ± 0.34, 0.92 ± 0.62) were also significantly lower than those of the group A and B patients. QGS may be a useful method for the evaluation of cardiac systolic and diastolic function, especially in patients with normal systolic function and diastolic dysfunction.

Risk stratification of cardiovascular events in patients at all stages of chronic kidney disease using myocardial perfusion SPECT

BackgroundCardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Therefore, stratification of the prognostic risk of cardiovascular events is useful for their clinical management. We evaluated the ability of electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) to predict cardiac events among Japanese patients at all stages of CKD including those on hemodialysis. MethodsPatients with CKD undergoing ECG-gated myocardial perfusion SPECT to investigate suspected ischemic heart disease were followed up to monitor retrospectively major cardiac events including cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. Summed stress score, summed rest score, and summed difference score were estimated with a 20 segment 5-point scoring model. The severity of CKD was divided into five levels based on estimated glomerular filtration rate (eGFR) revised for the Japanese population. ResultsThe follow-up period was 25.8±11.0 months. Sixty-two major cardiac events (cardiac death, n=30; non-fatal myocardial infarction, n=13; unstable angina pectoris, n=19) developed in 2243 patients during the first year of follow-up. The findings of multivariate Cox proportional hazards regression analysis indicated that diabetes, eGFR, the summed difference score, and summed stress score were significant independent predictors of cardiac events. The major cardiac event rate at one year increased in proportion to the progression of CKD stage. The major cardiac event-free survival rate decreased steeply over time in patients with CKD stage 5 compared with those who had CKD stages 4 or less. ConclusionMyocardial perfusion SPECT can contribute to the prediction of cardiac events and survival in patients at all stages of CKD including those on hemodialysis.

Evaluation of regional work from ECG-gated SPECT images through solution of equations of continuity for fluids--mechanical cardiac work calculated using thin wall model

Regional contraction work (RCW) of left ventricle (LV) was evaluated from cardiac perfusion images of ECG-gated single photon emission computed tomography (ECG-SPECT). The mechanical work was computed as a product of force and displaced distance. Force was determined from Laplace's law under a rectangle pressure. Deformation of wireframe representing LV was calculated from equations of continuity for two-dimensional fluids. Experiments were performed with homemade life-sized cardiac models. Total contraction work (TCW) and stroke work (SW) were 524.0 ± 166.1 mJ/beat and 709.8 ± 169.5 mJ/beat, respectively, in normal subjects (n = 23). Moderate correlation was seen between TCW and SW (y = −43.4 + 0.779 x, r = 0.815). The regional contraction amplitude (RCA), synchronous contraction index and RCW were 35.4 ± 3.5%, 95.4 ± 3.1% and 5.58 ± 0.97 mJ cm−2/beat in normal subjects, whereas those in patients with decreased ejection raction (EF) ≤ 30% (n = 6) were 19.6 ± 7.7%, 64.4 ± 32.2% and 2.58 ± 0.82 mJ cm−2/beat (p < 0.0001, Student's t-test). There was a poor correlation between RCW and RCA (y = 1.648 ± 0.116 x, r = 0.501) in normal subjects, suggesting that it might not be suitable to use RCA as an alternative to evaluate RCW.

Combined Assessment of Myocardial Perfusion and Function by ECG-Gated Myocardial Perfusion Single-Photon Emission Computed Tomography for the Prediction of Future Cardiac Events in Patients With Type 2 Diabetes Mellitus

The mid-term prognostic significance of ECG-gated single-photon emission computed tomography (SPECT) remains unclear in Japanese patients with type 2 diabetes mellitus (DM). In the present study rates of future cardiac events (nonfatal acute myocardial infarction (AMI), cardiac death (CD) and severe heart failure (HF) requiring hospitalization) were compared in patients with and without DM. 1,810 patients (563 DM and 1,247 non-DM) we followed for a mean of 26.3±15.5 months. Summed stress score (SSS), summed difference score (SDS), poststress ejection fraction (EF) and resting end-diastolic volume (EDV) were calculated. In total, 20 cases of AMI (9 in DM (1.59%) and 11 in non-DM (0.88%)), 20 of CD (7 in DM patients (1.24%) and 13 in non-DM (1.04%)) and 54 of severe HF (31 in DM (5.5%) and 23 in non-DM (1.84%)) occurred. Univariate Cox analysis showed that, in DM patients, predictors of total cardiac events were poststress EF (Wald 60.4; P<0.001), resting EDV (Wald 53.8; P<0.001), SSS (Wald 39.6; P<0.001), SDS (Wald 26.1; P<0.001), history of prior MI (Wald 4.32; P<0.05) and hemoglobin A(1c) value (Wald 4.30; P<0.05). Multivariate Cox analysis showed that poststress EF (Wald 9.85; P<0.01) and SDS (Wald 6.19; P<0.01) were independent predictors of total cardiac events. Combined assessment of perfusion and function by ECG-gated SPECT may predict future cardiac events in type 2 DM patients.

Duration and type of therapy for diabetes: Impact on cardiac risk stratification with stress electrocardiographic-gated SPECT myocardial perfusion imaging

BackgroundStress electrocardiogram(ECG)-gated single photon emission computed tomography (SPECT) imaging is highly effective in risk stratification of diabetic patients for adverse cardiac events. While patients with diabetes are predisposed to a more aggressive progression of vascular disease, the impact of its duration and type of therapy on risk stratification are unknown. MethodsFrom the Hartford Hospital Nuclear Cardiology clinical database, 886 diabetic patients who underwent exercise or pharmacologic stress ECG-gated SPECT were identified, with complete follow-up regarding the occurrence of adverse cardiac events and information regarding the duration of diabetes and the type of therapy (insulin vs oral medication only) at the time of testing. Images were interpreted using the American College of Cardiology/ASNC standard 17-segment scoring model. ResultsOf the 886 diabetic patients, 98 (11%) suffered cardiac death or non-fatal myocardial infarction during follow-up (2.5 ± 1.6 years). A receiver operator characteristics curve demonstrated that diabetes ≥10 years in duration provided the maximal sum of sensitivity and specificity for the prediction of adverse cardiac outcomes. Multivariate analysis identified the following as independent predictors of adverse outcome: Post-stress ejection fraction (EF) <40% (P = .001), age (P = .004), insulin therapy (P = .031), diabetes duration >10 years (P = .038), summed stress score (SSS) >8 (P = .046). For patients with an SSS >8, diabetes duration and type of therapy significantly enhanced risk stratification. Similar findings emerged for patients with a post-stress EF <40%. ConclusionFor diabetic patients undergoing stress ECG-gated SPECT myocardial perfusion imaging, disease duration and type of therapy provide independent and incremental prognostic information. Integration of these variables with this cardiovascular imaging technology significantly enhances cardiac risk stratification.

Diagnostic Value of Adenosine-Induced Left Ventricular Diastolic Dysfunction for Detecting Coronary Artery Restenosis in Patients Undergoing Stent Implantation by Stress ECG-Gated Myocardial Perfusion SPECT - A Pilot Study -

Usefulness of diastolic dysfunction after adenosine stress for detecting coronary stenosis has not been defined. The diagnostic accuracy of a combination of myocardial perfusion and diastolic function, as defined by prolongation of time to peak-filling rate (TTPF)/R-R and myocardial perfusion alone for the detection of coronary restenosis, was evaluated. We used rest (201)Tl/ adenosine stress (99m)Tc-tetrofosmin myocardial perfusion singlephoton emission computed tomography (SPECT) in 70 patients. Patients were divided into the following 4 groups: 20 patients with normal SPECT without stent (Control group), 20 patients showing normal SPECT without coronary restenosis (Group 1), 16 patients showing significant coronary restenosis and myocardial ischemia (Group 2a) and 14 patients showing significant coronary restenosis without myocardial ischemia (Group 2b). The TTPF, which was calculated by quantitative gated SPECT (QGS)/R-R, was not different between after stress and at rest in Control group (0.18±0.02 vs 0.19±0.04, P=NS). The TTPF/R-R after stress was significantly lower than that at rest in Group 1 (0.17±0.02 vs 0.18±0.03, P<0.05), but TTPF/R-R after stress was significantly higher than that at rest in Groups 2a and 2b (0.22±0.03 vs 0.16±0.03, P<0.001 in Group 2a and 0.19±0.02 vs 0.16±0.02, P<0.001 in Group 2b, respectively). Diagnostic accuracy improved from 72% to 92% when prolongation of TTPF/R-R was taken into account (P<0.001). Diastolic dysfunction after stress was an accurate marker for detecting significant restenosis following stent implantation.