Thallium-gated SPECT in patients with major myocardial infarction: effect of filtering and zooming in comparison with equilibrium radionuclide imaging and left ventriculography.

The effect of filtering and zooming on 201TI-gated SPECT was evaluated in patients with major myocardial infarction. METHODS: Rest thallium (TI)-gated SPECT was performed with a 90 degrees dual-head camera, 4 h after injection of 185 MBq 201TI in 32 patients (mean age 61 +/- 11 y) with large myocardial infarction (33% +/- 17% defect on bull's eye). End diastolic volume (EDV), end systolic volume (ESV) and left ventricular ejection fraction (LVEF) were calculated using a commercially available semiautomatic validated software. First, images were reconstructed using a 2.5 zoom, a Butterworth filter (order = 5) and six Nyquist cutoff frequencies: 0.13 (B5.13), 0.15 (B5.15), 0.20 (B5.20), 0.25 (B5.25), 0.30 (B5.30) and 0.35 (B5.35). Second, images were reconstructed using a zoom of 1 and a Butterworth filter (order = 5) (cutoff frequency 0.20 [B5.20Z1]) (total = 32 x 7 = 224 reconstructions). LVEF was calculated in all patients using equilibrium radionuclide angiocardiography (ERNA). EDV, ESV and LVEF were measured with contrast left ventriculography (LVG). RESULTS: LVEF was 39% +/- 2% (mean +/- SEM) for ERNA and 40% +/- 13% for LVG (P = 0.51). Gated SPECT with B5.20Z2.5 simultaneously offered a mean LVEF value (39% +/- 2%) similar to ERNA (39% +/- 2%) and LVG (40% +/- 3%), optimal correlations with both ERNA (r = 0.83) and LVG (r = 0.70) and minimal differences with both ERNA (-0.9% +/- 7.5% [mean +/- SD]) and LVG (1.1% +/- 10.5%). As a function of filter and zoom choice, correlation coefficients between ERNA or LVG LVEF, and gated SPECT ranged from 0.26 to 0.88; and correlation coefficients between LVG and gated SPECT volumes ranged from 0.87 to 0.94. There was a significant effect of filtering and zooming on EDV, ESV and LVEF (P < 0.0001). Low cutoff frequency (B5.13) overestimated LVEF (P < 0.0001 versus ERNA and LVG). Gated SPECT with 2.5 zoom and high cutoff frequencies (B5.15, B5.20, B5.25, B5.30 and B5.35) overestimated EDV and ESV (P < 0.04) compared with LVG. This volume overestimation with TI-gated SPECT in patients with large myocardial infarction was correlated to the infarct size. A zoom of 1 underestimated EDV, ESV and LVEF compared with a 2.5 zoom (P < 0.02). CONCLUSION: Accurate LVEF measurement is possible with TI-gated SPECT in patients with major myocardial infarction. However, filtering and zooming greatly influence EDV, ESV and LVEF measurements, and TI-gated SPECT overestimates left ventricular volumes, particularly when the infarct size increases.     

Automated ejection fraction determination from gated myocardial FDG-PET data

BACKGROUND: The aim of this study was to determine the potential of the automated calculation of the left ventricular ejection fraction from gated myocardial positron emission tomography (PET) scans. METHODS: We retrospectively analyzed the data of 20 patients who underwent both gated fluorine 18 deoxyglucose (FDG)-PET and equilibrium radionuclide angiography (ERNA). Gated PET data were analyzed by 2 independent programs (ie, quantitative gated single photon emission computed tomography [QGS]) originally developed for gated single photon emission computed tomography studies and functional polarmap (FPM) originally developed for the analysis of (functional) dynamic PET studies. ERNA data were used as the gold standard. RESULTS: Both QGS and FPM left ventricular ejection fraction results correlated highly with ERNA (y = 0.90 x x-5.9, r = 0.86, P < .0001; y = 0.80 x x+3.3, r = 0.84, P < .0001, respectively). The correlation between FPM and QGS left ventricular ejection fraction results was even higher (y = 0.89 x x+8.6, r = 0.97, P < .0001). Bland-Altman plots showed systematic differences in the left ventricular ejection fraction of -9.6% +/- 7.5% (QGS vs ERNA), -3.8% +/- 7.8% (FPM vs ERNA), and -5.8% +/- 3.5% (QGS vs FPM). Further comparison of the left ventricular volumes revealed systematic difference between QGS and FPM. Our results indicate that the correlation between the different left ventricular ejection fractions shows little sensitivity to errors in the left ventricular volumes; however, the exact relationship is influenced by these errors. CONCLUSION: It is concluded that the automated determination of the left ventricular ejection fraction from gated PET data has significant potential; its results are highly and significantly correlated with ERNA. However, the methods presented here require additional calibration before final accuracy and clinical applicability can be determined.     

Effect of temporal sampling on evaluation of left ventricular ejection fraction by means of thallium-201 gated SPET: comparison of 16- and 8-interval gating, with reference to equilibrium radionuclide angiography

Gated myocardial single-photon emission tomography (SPET) allows the evaluation of left ventricular ejection fraction (LVEF), but temporal undersampling may lead to systolic truncation and ejection fraction underestimation. The aim of this study was to evaluate the impact of temporal sampling on thallium gated SPET LVEF measurements. Fifty-five consecutive patients (46 men, mean age 62+/-12 years) with a history of myocardial infarction (anterior 31, inferior 24) were studied. All patients underwent equilibrium radionuclide angiography (ERNA) and gated SPET 4 h after a rest injection of 185 MBq (5 mCi) of thallium-201 using either 8-interval (group 1, n=25) or 16-interval gating (group 2, n=30). In group 2, gated SPET acquisitions were automatically resampled to an 8-interval data set. Projection data were reconstructed using filtered back-projection (Butterworth filter, order 5, cut-off 0.20). LVEF was then calculated using commercially available software (QGS). A higher correlation between gated SPET and ERNA was obtained with 16-interval gating (r=0.94) compared with the resampled data set (r=0.84) and 8-interval gating (r=0.71). Bland-Altman plots showed a dramatic improvement in the agreement between gated SPET and ERNA with 16-interval gating (mean difference: -0.10%+/-5%). Using multiple ANOVA, temporal sampling was the only parameter to influence the difference between the two methods. When using 8-interval gating, gated SPET LVEF was overestimated in women and underestimated in men (ERNA minus gated SPET = -4.0%+/-9.6% in women and 3.6%+/-7.6% in men, P=0.01). In conclusion, 16-interval thallium gated SPET offered the best correlation and agreement with ERNA, and should be preferred to 8-interval gated acquisition for LVEF measurement.     

Validation of SPECT equilibrium radionuclide angiographic right ventricular parameters by cardiac magnetic resonance imaging

BACKGROUND: Recent advances in the treatment of primary pulmonary hypertension (PPH), and in surgery to correct tetralogy of Fallot (TOF), have rekindled interest in evaluating right ventricular (RV) volume and ejection fraction (EF). The purpose of this investigation was to determine the accuracy of RV functional parameters assessed by single photon emission computed tomography (SPECT) equilibrium radionuclide angiography (ERNA). METHODS AND RESULTS: Twenty-eight patients with PPH (n = 15) or TOF (n = 13) (aged 28 +/- 14 years; 57% male) were analyzed by means of SPECT ERNA algorithms that automatically identified mid-RV tomographic planes, generated regions isolating the right ventricle from other structures, and presented RV-segmented regions as a cinematic display. RV EF and volumes were computed and compared with values obtained by magnetic resonance imaging (MRI). Mean values were not different between SPECT ERNA and MRI for RV EF, end-diastolic volume, and end-systolic volume (42% +/- 11% vs 41% +/- 10%, 135 +/- 67 mL vs 139 +/- 91 mL, and 87 +/- 54 mL vs 85 +/- 61 mL, respectively; P = not significant for all comparisons). Significant linear correlation (P <.0001) was found between SPECT ERNA and MRI for RV EF, end-diastolic volume, and end-systolic volume (r = 0.85, r = 0.94, and r = 0.93, respectively). No statistically significant trends or biases for RV EF were found. Intraobserver and interobserver comparisons demonstrated good reproducibility. As expected, RV volume was significantly higher and RV EF was significantly lower for patients with PPH and TOF than were values for individuals at low likelihood for coronary artery disease or other cardiac disease. CONCLUSIONS: SPECT ERNA provides accurate, reproducible assessment of RV volumes and EF and should prove useful in evaluating the magnitude of RV dysfunction in patients and in providing an objective means with which to assess the results of therapeutic interventions.     

201Tl and 99mTc-MIBI gated SPECT in patients with large perfusion defects and left ventricular dysfunction: comparison with equilibrium radionuclide angiography.

Left ventricular ejection fraction (LVEF) is a major prognostic factor in coronary artery disease and may be computed by 99mTc-methoxyisobutyl isonitrile (MIBI) gated SPECT. However, 201Tl remains widely used for assessing myocardial perfusion and viability. Therefore, we evaluated the feasibility and accuracy of both 99mTc-MIBI and 201Tl gated SPECT in assessing LVEF in patients with myocardial infarction, large perfusion defects and left ventricular (LV) dysfunction. METHODS: Fifty consecutive patients (43 men, 7 women; mean age 61 +/- 17 y) with a history of myocardial infarction (anterior, 26; inferior, 18; lateral, 6) were studied. All patients underwent equilibnum radionuclide angiography (ERNA) and rest myocardial gated SPECT, either 1 h after the injection of 1110 MBq 99mTc-MIBI (n = 19, group 1) or 4 h after the injection of 185-203 MBq 201Tl (n = 31, group 2) using a 90 degrees dual-head camera. After filtered backprojection (Butterworth filter: order 5, cutoff 0.25 99mTc or 0.20 201Tl), LVEF was calculated from reconstructed gated SPECT with a previously validated semiautomatic commercially available software quantitative gated SPECT (QGS). Perfusion defects were expressed as a percentage of the whole myocardium planimetered by bull's-eye polar map of composite nongated SPECT. RESULTS: Gated SPECT image quality was considered suitable for LVEF measurement in all patients. Mean perfusion defects were 36% +/- 18% (group 1), 33% +/- 17% (group 2), 34% +/- 17% (group 1 + group 2). LVEF was underestimated using gated SPECT compared with ERNA (34% +/- 12% and 39% +/- 12%, respectively; P = 0.0001). Correlations were high (group 1, r= 0.88; group 2, r = 0.76; group 1 + group 2, r = 0.82), and Bland-Altman plots showed a fair agreement between gated SPECT and ERNA. The difference between the two methods did not vary as LVEF, perfusion defect size or seventy increased or when the mitral valve plane was involved in the defect. CONCLUSION: LVEF measurement is feasible using myocardial gated SPECT with the QGS method in patients with large perfusion defects and LV dysfunction. However, both 201Tl and 99mTc-MIBI gated SPECT similarly and significantly underestimated LVEF in patients with LV dysfunction and large perfusion defects.     

Assessment of left ventricular function by 201Tl SPECT using left ventricular cavity-to-myocardium count ratio

Equilibrium radionuclide angiography (ERNA) is the 'gold standard' for assessing left ventricular ejection fraction (LVEF). The aim of the study was to determine whether the left ventricular cavity-to-myocardium count ratio (LVCMR) from 201Tl myocardial single photon emission computed tomography (SPECT) correlated with LVEF assessed by ERNA. The study group included 159 consecutive patients (117 male, 42 female), aged 59+/-12 years, who underwent both 201Tl SPECT and ERNA at rest on the same day. The LVCMR was calculated from a mid-ventricular short axis slice on redistribution studies, using two regions of interest (ROIs). One ROI was placed in the centre of the left ventricular cavity (C) and the other was placed in the myocardium with maximum uptake (Mmax): LVCMR= (C/Mmax) x 100. The correlation between LVCMR and LVEF was r = 0.85 (y = 0.943x+5.002; P < 0.0001). The mean calculated values +/- 1 SD were LVCMR=54+/-16% and LVEF=52+/-15%. In conclusion, LVCMR from 201Tl SPECT studies was closely correlated with LVEF from ERNA studies and can be used to easily and rapidly estimate left ventricular function.     

Myocardial tracking, a new method to calculate ejection fraction with gated SPECT: validation with (201)Tl versus planar angiography.

Left ventricular ejection fraction (LVEF) and viability are essential variables for the prognosis of myocardial infarction and can be measured simultaneously by (201)Tl gated SPECT; however, most algorithms tend to underestimate LVEF. This study aimed to evaluate a new myocardial tracking algorithm, MyoTrack (MTK), for automatic LVEF calculation. METHODS: A rest/redistribution (20 min/4 h) (201)Tl gated SPECT protocol followed immediately by a (99m)Tc equilibrium radionuclide angiography (ERNA) was performed in 75 patients with history of myocardial infarction. Quality of myocardial uptake was evaluated from count statistics and automatic quantification of defect sizes and severities (CardioMatch). LVEFs were calculated both with Germano's quantitative gated SPECT (QGS) algorithm and with MTK. Briefly, the originality of this algorithm resides in the unique end-diastole segmentation, matching to a template and motion field tracking throughout the cardiac cycle. RESULTS: ERNA LVEF averaged 33% +/- 14%. QGS significantly underestimated this value at 20 min (30% +/- 13%, P < 0.001) and at 4 h (30% +/- 13%, P < 0.0001). By contrast, MTK did not miscalculate LVEF at 20 min (34% +/- 14%, probability value was not significant) though a similar underestimation occurred at 4 h (31% +/- 13%, P < 0.02). Individual differences between early and late gated SPECT values and differences between gated SPECT and ERNA values did not correlate with the extension of perfusion defects, count statistics, or heart rate. CONCLUSION: MTK algorithm accurately calculates LVEF on early/high-count images compared with ERNA [corrected], even in patients with severe perfusion defects, but tends to underestimate LVEF on delayed/low-contrast images, as other algorithms do.     

Planar imaging versus gated blood-pool SPECT for the assessment of ventricular performance: a multicenter study.

Gated blood-pool SPECT (GBPS), inherently 3-dimensional (3D), has the potential to replace planar equilibrium radionuclide angiography (ERNA) for computation of left ventricular ejection fraction (LVEF), analysis of regional wall motion (RWM), and analysis of right heart function. The purpose of this study was to compare GBPS and ERNA for the assessment of ventricular function in a large, multicenter cohort of patients. METHODS: One hundred seventy-eight patients referred in the usual manner for nuclear medicine studies underwent ERNA followed by GBPS. Each clinical site followed a GBPS acquisition protocol that included 180 degrees rotation, a 64 by 64 matrix, and 64 or 32 views using single- or double-head cameras. Transverse GBPS images were reconstructed with a Butterworth filter (cutoff frequency, 0.45-0.55 Nyquist; order, 7), and short-axis images were created. All GBPS studies were processed with a new GBPS program, and LVEF was computed from the isolated left ventricular chamber and compared with standard ERNA LVEF. Reproducibility of GBPS LVEF was evaluated, and right ventricular ejection fraction (RVEF) was computed in a subset of patients (n = 33). Using GBPS, RWM and image quality from 3D surface-shaded and volume-rendered cine displays were evaluated qualitatively in a subset of patients (n = 30). RESULTS: The correlation between GBPS LVEF and planar LVEF was excellent (r = 0.92). Mean LVEF was 62.2% for GBPS and 54.1% for ERNA. The line of linear regression was GBPS LVEF = (1.04 x ERNA LVEF) + 6.1. Bland-Altman plotting revealed an increasing bias in GBPS LVEF with increasing LVEF (Y = 0.13x + 0.61; r = 0.30; mean difference = 8.1% +/- 7.0%). Interoperator reproducibility of GBPS LVEF was good (r = 0.92). RVEF values averaged 59.8%. RWM assessment using 3D cine display was enhanced in 27% of the studies, equivalent in 67%, and inferior in 7%. CONCLUSION: GBPS LVEF was reproducible and correlated well with planar ERNA. GBPS LVEF values were somewhat higher than planar ERNA, likely because of the exclusion of the left atrium.     

Predictors of improvement in left ventricular ejection fraction with carvedilol for congestive heart failure

BACKGROUND: Beta-blocker therapy has been reported to improve survival and left ventricular ejection fraction (LVEF) in the setting of congestive heart failure (CHF). The magnitude and predictors of improved LVEF are unclear. METHODS: A total of 295 patients were enrolled in the study. Inclusion criteria were LVEF <35% at baseline and symptomatic (New York Heart Association class II to IV) CHF despite treatment with at minimum an angiotensin-converting enzyme inhibitor. Carvedilol was initiated at 3.125 mg twice daily and titrated to a target dose of 25 or 50 mg twice daily, depending on the patient's weight. Paired pretreatment baseline and 9 months with treatment follow-up quantitative LVEFs (assessed by resting radionuclide ventriculograms) were obtained in 161 (55 %) of the patients. RESULTS: LVEF improved from 25% +/- 6% at baseline to 36%+/-12% at follow-up (P<.001). Mean change in LVEF (deltaLVEF) was greater for nonischemic cardiomyopathy (NICM) (+14.5+/-2 LVEF points) than ischemic cardiomyopathy (deltaLVEF +/- 7.6+/-10 EF points, P = .001). The deltaLVEF was > or =21 LVEF points in 30% of the NICM group versus 10% of the ischemic cardiomyopathy group. Conversely, the deltaLVEF was unchanged to minimally improved (< or =5 LVEF points) in 21% of the NICM group versus 52% of the ischemic cardiomyopathy group. Multivariable analysis identified NICM and recent onset of congestive heart failure as correlates of improved LVEF. CONCLUSIONS: Carvedilol significantly improved LVEF, especially in patients with NICM and those with recent onset of CHF.     

Assessment of ejection fraction with Tl-201 gated SPECT in myocardial infarction: Precision in a rest-redistribution study and accuracy versus planar angiography

BACKGROUND. Viability and left ventricular ejection fraction (LVEF) are essential measures for the assessment of myocardial infarction (MI). These 2 variables may be evaluated simultaneously by means of thallium-201 gated single photon emission computed tomography (SPECT); however, the precision and accuracy of LVEF measurements with this isotope remain controversial, particularly in cases of extended perfusion defects and poor count densities. METHODS AND RESULTS. Fifty patients with a history of MI underwent a 20-minute rest and a 4-hour redistribution Tl-201 gated SPECT viability protocol, immediately followed by a technetium-99m planar equilibrium radionuclide angiography (ERNA). On gated SPECT images, various count statistics were calculated, and perfusion was automatically quantified by means of CardioMatch, which provided both the size and severity of MI defects. Rest and redistribution LVEFs were determined from gated SPECT with Germano's algorithm, whereas LVEFs were calculated from ERNA using the manufacturer's software. Mean LVEF values calculated with rest gated SPECT, redistribution gated SPECT, and planar ERNA were 30% +/- 13%, 30% +/- 13% and 33% +/- 13%, respectively. Significant differences between repeated gated SPECT LVEFs were not shown by means of the paired t test. Correlation coefficients were high between 20-minute and 4-hour scans (r = 0.89) and between gated SPECT and ERNA (r = 0.88 and r = 0.92 at 20 minutes and 4 hours, respectively). Additionally, close agreement between gated SPECT and ERNA was shown by means of the Bland-Altman plot, despite an underestimation of 3 units. Finally, neither the technical conditions (count density, heart rate, lung uptake, etc) nor the perfusion alteration (size, severity, redistribution) appeared to interfere with the precision and accuracy of gated SPECT LVEF measurement. CONCLUSION. Tl-201 gated SPECT is a precise method for assessing LVEF within the same patient at 4-hour intervals, even with a substantial count decay, and it gives accurate results compared with planar ERNA, even in the case of large perfusion defects.     

Accuracy of the automated assessment of left ventricular function with gated perfusion SPECT in the presence of perfusion defects and left ventricular dysfunction: Correlation with equilibrium radionuclide ventriculography and echocardiography

BACKGROUND: Gated single photon emission computed tomography (SPECT) with automated methods allows the quantitative assessment of left ventricular function and perfusion; however, its accuracy must be defined for patients with large earlier infarctions and severe rest perfusion defects, in whom the estimation of endocardial and epicardial borders might be more difficult, even with automated edge-detection techniques. METHODS AND RESULTS: We prospectively compared the automated measurements of left ventricular ejection fraction (LVEF) and volumes from rest-injected gated Technetium 99m (Tc99m) perfusion SPECT with equilibrium radionuclide angiocardiography (ERNA) in 62 patients and the assessment of regional function with echocardiography in 22 patients. Forty-six patients had an earlier myocardial infarction (mean defect size, 34% of left ventricle; SD, 12.7%; range, 8% to 56%); 27 patients had large defects (> or = 20% of left ventricle; LVEF range, 8% to 75%). LVEF, as determined with Cedars-Sinai software (quantitative gated SPECT), correlated well with ERNA (r = 0.941; y = 1.003x + 1.15; P<.0001; SE of the estimate = 6.3%; mean difference -1.3% for LVEF) in the entire study population and in the subgroups of patients with an earlier infarction, severe defects, and large infarctions (> or = 20% of the left ventricle). A correlation existed between gated SPECT and ERNA volumes (r = 0.882, y = 1.040x - 14.7, P<.0001 for end-diastolic volume; r = 0.954, y = 1.147x - 13.9, P<.0001 for end-systolic volumes with the count-ratio technique), but with wider limits of agreement. The exact segmental score agreement between gated SPECT and echocardiography for regional function was 79.8% (281 of 352, kappa = 0.682). CONCLUSIONS: Automated gated SPECT provides an accurate assessment of ejection fraction and regional function, even in the presence of an earlier myocardial infarction with large perfusion defects and significant left ventricular dysfunction.     

Gated-SPECT equilibrium radionuclide angiography in right ventricular assessment of patients with repaired tetralogy of Fallot

BACKGROUND: The long-term prognosis of patients with tetralogy of Fallot (TF) who have undergone repair is determined by right ventricular dilatation resulting from residual pulmonary insufficiency. We have studied the values of right and left ventricle systolic function obtained by gated single photon emission computed tomography (SPECT) equilibrium radionuclide angiography (ERNA) in these patients. METHODS: A study population of 62 patients with surgically repaired TF underwent gated-SPECT ERNA to determine ejection fraction of the right and left ventricle and dimensions of the right ventricle and pulmonary infundibulum. Results were compared with those of a group of 11 patients without heart disease. RESULTS: RVEF (34% vs. 40%, P=0.02) and LVEF (49% vs. 54%, P=0.03) were significantly lower in patients with TF than in the control group. The RVEF and LVEF variation coefficients were 9% and 6.2%, respectively. Volumes of the right ventricle (P=0.003) were significantly greater than those of the control group, although variation coefficients were 15%. CONCLUSIONS: Gated-SPECT ERNA is a non-invasive method of assessing ejection fraction in patients with repaired TF. In these patients, the ejection fraction is decreased in both ventricles, whereas size of the right ventricle is significantly increased. Reproducibility of the RVEF calculation is good, but in the case of volumes it is suboptimal.     

Myocardial scar and insulin resistance predict cardiovascular events in severe ischaemic myocardial dysfunction: a perfusion-metabolism positron emission tomography study

BACKGROUND: Clinical outcome can be predicted by metabolism-perfusion positron emission tomography (PET) in patients with severe ischaemic left ventricular dysfunction. This study determined whether the amount of viable or non-viable myocardium detected with a PET scan or clinical-functional parameters might predict cardiovascular events. METHODS: All patients had previous myocardial infarction (>6 months previously) and left ventricular ejection fraction (LVEF) <40%. Metabolism-perfusion PET, echocardiogram and coronary angiography were provided. All subjects underwent short euglycaemic-hyperinsulinaemic clamp before the metabolism study. The dysfunctioning segment was defined as hibernating myocardium when metabolism was normal-moderately reduced with impaired perfusion (mismatch flow-metabolism). Cardiac death, hospital admission for myocardial infarction or heart failure were considered cardiovascular events. RESULTS: Ninety-three patients (71 males, aged 64.2 years) were studied. The LVEF was 30.2+/-7.7%; 48 (51.6%) suffered an anterior myocardial infarction. Fifty-three (54.1%) subjects were treated with coronary revascularization; all had optimal medical therapy. Cardiovascular events occurred in 20/93 patients at 1-year follow-up (event group). Age (P=0.7), diabetes mellitus (P=0.6) and rate of coronary revascularization (P=0.3) were not different in the two groups. Patients who experienced cardiovascular events had larger non-viable myocardium (5.8+/-2.7 vs. 4.1+/-2.6, P=0.01), lower metabolic rate glucose (1.3+/-0.6 vs. 1.7+/-0.7 ml . kg . min, P=0.04) but similar hibernating myocardium (1.6+/-1.6 vs. 1.7+/-2, P=0.8) and baseline LVEF (28.1+/-4.8 vs. 30.7+/-8.3%, P=0.08). Having more then five non-viable segments and a metabolic rate for glucose of <0.9 mg . kg . min predicted a worse prognosis (P=0.04, log rank, 3.89; and P=0.004, log rank, 8.1, respectively). CONCLUSION: Non-viable myocardium revealed with PET predicts mid-term clinical prognosis. Insulin resistance seems to influence the outcome.     

Accuracy of left ventricular ejection fraction determined by gated myocardial perfusion SPECT with Tl-201 and Tc-99m sestamibi: Comparison with first-pass radionuclide angiography

BACKGROUND: We compared estimates of left ventricular ejection fraction (LVEF) assessed by gated single photon emission computed tomography (SPECT), using both technetium-99m sestamibi and thallium-201, with those obtained by first-pass radionuclide angiography (FPRNA) in patients with a broad spectrum of LVEF and perfusion abnormalities. METHODS: Sixty-three patients were randomly selected to undergo a dual isotope gated SPECT study (rest Tl-201 followed by adenosine Tc-99m sestamibi scintigraphy). Studies were processed by use of the Cedars quantitative gated SPECT software. FPRNA was acquired during an intravenous bolus injection of Tc-99m sestamibi and processed with a commercially available software. RESULTS: The estimates of LVEF were similar (P = NS) with Tl-201 gated SPECT (54% +/- 15%), Tc-99m gated SPECT (54% +/- 16%), and FPRNA (54% +/- 12%). There was an excellent correlation between Tc-99m and Tl-201 gated SPECT (Pearson's r = 0.92, P < .0001). There were also good linear correlations between Tc-99m sestamibi gated SPECT and FPRNA (Pearson's r = 0.85, P < .0001), as well as between Tl-201 gated SPECT and FPRNA (Pearson's r = 0.84, P < .0001). In the 16 patients with LVEF < 50%, Tc-99m sestamibi gated SPECT and FPRNA (Pearson's r = 0.84, P < .0001) and Tl-201 gated SPECT and FPRNA (Pearson's r = 0.92, P < .0001) correlated well. CONCLUSION: LVEF can be accurately assessed by gated SPECT with either Tc-99m sestamibi or Tl-201 in properly selected patients with normal or depressed left ventricular function.     

Additive effects of spironolactone and candesartan on cardiac sympathetic nerve activity and left ventricular remodeling in patients with congestive heart failure.

The activation of the renin-angiotensin-aldosterone system prevents the uptake of norepinephrine in the myocardium. However, the additive effects of combined spironolactone and candesartan on cardiac sympathetic nerve activity (CSNA) have not been determined. We investigated the effects of the angiotensin-receptor blocker candesartan alone and in combination with spironolactone on CSNA in patients with congestive heart failure (CHF). METHODS: Fifty patients with CHF (left ventricular ejection fraction [LVEF] < 45%) were randomly assigned to candesartan plus spironolactone (group A; n = 25) or to candesartan alone (group B; n = 25). All patients were also treated with a loop diuretic. The delayed percent denervation, delayed heart-to-mediastinum count (H/M) ratio, and washout rate (WR) were determined from (123)I-metaiodobenzylguanidine (MIBG) scintigraphy, and plasma brain natriuretic peptide (BNP) concentration was measured before and 6 mo after treatment. The LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LVEF were also determined by echocardiography. RESULTS: After 6 mo, all of these parameters were improved in both groups. However, the degree of change in the percent denervation was -14 +/- 12 in group A and -7 +/- 10 in group B (P < 0.05); the change in the H/M ratio was 0.19 +/- 0.18 in group A and 0.08 +/- 0.14 in group B (P < 0.05), the change in WR was -12% +/- 8% in group A and -5% +/- 13% in group B (P < 0.05), and the change in plasma BNP was -100 +/- 83 pg/mL in group A and -43 +/- 97 pg/mL in group B (P < 0.05). The degree of change in LVEDV, LVESV, and LVEF in group A tended to be better than that in group B, but these changes were not statistically significant. Moreover, there were significant correlations between changes in the (123)I-MIBG scintigraphic findings and changes in the LVEDV (% denervation, r = 0.692, P < 0.001; H/M ratio, r = -0.437, P < 0.05; and WR, r = 0.505, P < 0.01) or the LVESV (% denervation, r = 0.663, P < 0.001; H/M ratio, r = -0.438, P < 0.05; and WR, r = 0.532, P < 0.01) in group A. In contrast, there was no relationship between these parameters in group B. CONCLUSION: These findings indicate that the combination of spironolactone and candesartan may be more beneficial for CSNA and LV performance than candesartan alone in patients with CHF.     

Spironolactone improves cardiac sympathetic nerve activity and symptoms in patients with congestive heart failure.

We evaluated whether spironolactone would improve cardiac sympathetic nerve activity and symptoms in patients with congestive heart failure (CHF). METHODS: Thirty patients with CHF (left ventricular ejection fraction [LVEF] < 40%; mean, 30% +/- 9%) were treated with an angiotensin-converting enzyme inhibitor, a loop diuretic, and, in most cases, digoxin. Fifteen patients (group A) were assigned to additionally receive spironolactone (12.5-50 mg/day), and the remaining 15 patients (group B) continued their current regimen. Patients were studied before and 6 mo after treatment. The delayed heart-to-mediastinum count ratio (H/M ratio), delayed total defect score (TDS), and washout rate (WR) were determined from (123)I-meta-iodobenzylguanidine (MIBG) images. LVEF was determined by echocardiography, and New York Heart Association (NYHA) functional class was estimated. RESULTS: Before treatment, LVEF, TDS, H/M ratio, WR, and NYHA functional class were similar in both groups. With treatment, LVEF did not significantly improve in either group. However, after treatment in group A, TDS decreased from 37 +/- 9 to 25 +/- 13 (P = 0.0001), H/M ratio increased from 1.62 +/- 0.20 to 1.83 +/- 0.27 (P < 0.0001), and WR decreased from 51 +/- 9 to 40 +/- 15 (P < 0.001). In group B, these parameters did not significantly change. NYHA functional class improved in both groups (in group A, from 3.3 +/- 0.5 to 1.7 +/- 0.5 [P < 0.0001]; in group B, from 3.3 +/- 0.5 to 2.4 +/- 0.6 [P = 0.01]); this was a significantly greater improvement in group A than in group B (P < 0.01). CONCLUSION: Spironolactone improves cardiac sympathetic nerve activity and symptoms in patients with CHF.     

Exercise-induced stunning continues for at least one hour: evaluation with quantitative gated single-photon emission tomography

To elucidate the after-effect of exercise on left ventricular (LV) function, end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) were evaluated at 1 h after exercise and at rest by technetium-99m tetrofosmin gated myocardial single-photon emission tomography (SPET) using an automated program in 53 subjects. The subjects were grouped as follows: normal scan (n = 16), ischaemia (n = 19) and infarction (n = 18), based on the interpretation of perfusion images. Postexercise LVEF did not differ from resting LVEF in the groups with normal scan and infarction. In patients with ischaemia, postexercise EDV (90+/-17 ml, mean +/-SD) and ESV (44+/-15 ml) were significantly higher than EDV (84+/-15 ml, P = 0.001) and ESV (36+/-14 ml, P<0.0005) at rest. LVEF was significantly depressed 1 h after exercise (53%+/-9% vs 58%+/-9%, P<0.0001). In ischaemic patients with depressed postexercise LVEF, LVEF difference between rest and postexercise showed a significant correlation with the sum of defect scores, which were reversible from exercise to rest perfusion images (r = 0.92, P<0.0001). These results indicate that exercise-induced LV dysfunction (myocardial stunning) continues for at least 1 h in ischaemic patients and that the extent of LVEF depression is determined by the severity of ischaemia.     

Adenosine-induced long-standing postischemic left ventricular dysfunction evaluated with gated SPECT

OBJECTIVES: This study was performed to determine the after-effects of pharmacologic stress (adenosine) on left ventricular (LV) function-end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (LVEF)-with Tl-201 and Tc-99m MIBI SPECT. METHODS: A total of 263 patients were grouped according to the time interval between isotope injection and imaging. Group A: within 1 hour (n = 99; men, n = 48; women, n = 51; mean age: 63.2 years), subgrouped as patients with no perfusion defect (NPD; n = 61), reversible defect (RD; n = 33), and fixed defect (FD; n = 5). Group B: 1 to 2 hours (n = 110; men, n = 66; woman, n = 44; mean age, 63 years), NPD (n = 64), RD (n = 26), and FD (n = 20). 3) Group C: 2 to 3 hours (n = 54; men, n = 30; women, n = 24; mean age, 62 years); NPD (n = 22), RD (n = 17), and FD (n = 15). All patients were in sinus rhythm during the study and had no prior history of myocardial infarction. RESULTS: In group A, in the patients with RD, poststress LVEF was significantly depressed after adenosine infusion (53.1 +/- 9.5% vs 58.3 +/- 10.2%, P < 0.001) and showed a wall motion abnormality, which was worse after stress than during rest. The mean difference in LVEF (DeltaLVEF) between rest and stress was 5.2%. The DeltaLVEF in those patients with RD was significantly higher than that in the NPD (0.9%, P < 0.01) or FD (2.1%, P < 0.05) subgroups. Twenty of the 33 patients (60.6%) with RD showed an increase in LVEF > or = 5% from poststress to rest, and the poststress ESV (43.3 +/- 19.0 mL) was significantly higher than the ESV (38.5 +/- 18.4 mL, P < 0.01) at rest, but there was no significant difference in the EDV (90.5 +/- 26.4 vs 89.7 +/- 26.2 mL). In group B, DeltaLVEF was 1.5%, 4.4%, and 1.2% in patients with NPD, RD, and FD respectively. In group C, DeltaLVEF was 2.5%, 3.2%, and 0.9% in patients with NPD, RD, and FD respectively, and there was no significant difference in DeltaLVEF among patients. In group C, 4 of 17 patients (23.5%) with RD showed an increase in LVEF > or = 5% from poststress to rest. CONCLUSION: These results showed that adenosine stress-induced postischemic LV dysfunction is well noted on early quantitative gated SPECT in patients with RD and can also be observed on delayed gated SPECT, even though the incidence of LV dysfunction is less than that in early gated SPECT.     

Assessment of left ventricular ejection fraction with quantitative gated SPECT: Accuracy and correlation with first-pass radionuclide angiography

BACKGROUND: Quantitative gated single photon emission computed tomography (SPECT [QGS]) software is widely used for the assessment of left ventricular ejection fraction (LVEF). Potentially confounding variables that may affect the accuracy of quantitative analysis of LVEF remain undefined. This study evaluated the accuracy of QGS as a means of determining LVEF in a wide range of LVEF values; evaluated the effect of extracardiac activity, count statistics, heart size, and perfusion defects on the accuracy of QGS LVEF; and compared QGS LVEF obtained at rest with that obtained after stress. METHODS AND RESULTS: QGS-derived LVEF was compared with rest first-pass radionuclide angiography (FPRNA) LVEF in 400 electrocardiographic-gated SPECT studies. The overall correlation between QGS and FPRNA LVEF was only fair (r = 0.66, SEE = 11.85%). In 35 of the patient studies (9%) with high extracardiac activity, the automated software failed, and no correlation was obtained. In the remaining 365 patient studies (91%), left ventricular contours were successfully identified. In these studies, correlation was better (r = 0.74, SEE = 9.77%). Agreement was better for images with high counts (r = 0.81, SEE = 8.66%) than for images with low counts (r = 0.61, SEE = 11.17%). Patient studies with abnormal LVEF had better correlation (r = 0.77, SEE = 6.4%) than studies with normal LVEF (r = 0.46, SEE = 10.2%). Agreement between QGS LVEF and FPRNA LVEF was better in hearts with large end diastolic volumes (>104 mL) than in hearts with small volumes. Overall, mean QGS LVEF was lower than mean FPRNA LVEF (54%+/-14% vs. 58%+/-14%, P<.0001). There was no difference between mean rest and stress QGS LVEF in the same patients, even in patients with stress-induced ischemia. CONCLUSIONS: QGS is a valuable method for assessing resting LVEF. However, QGS LVEF is often lower than FPRNA LVEF. Accuracy is affected by high extracardiac activity, low count density, and small size of the left ventricle.     

Combination radiofrequency ablation with intratumoral liposomal doxorubicin: effect on drug accumulation and coagulation in multiple tissues and tumor types in animals

PURPOSE: To determine whether use of radiofrequency (RF) ablation combined with intravenously (IV) administered liposomal doxorubicin, as compared with use of RF ablation or doxorubicin alone, facilitates increased tissue coagulation and interstitial drug accumulation in animal models. MATERIALS AND METHODS: The institutional animal care and use committee approved this study. In experiment 1, multiple canine sarcomas were implanted in seven mildly immunosuppressed dogs and grown to a mean diameter of 4.8 cm. Tumors were assigned to three treatment groups: internally cooled RF ablation (12 minutes, 2000-mA pulsed technique) followed by IV liposomal doxorubicin (10 mg per animal) (n = 6), RF ablation alone (n = 6), and liposomal doxorubicin alone (n = 4). In experiment 2, the livers and kidneys of 10 rabbits and the thigh muscles of 10 rats were randomly assigned to one of two treatment groups: conventional RF ablation (90 degrees C +/- 2, 5 minutes) followed by IV liposomal doxorubicin (5 mg per rabbit, 1 mg per rat) or RF ablation alone (n = 5, each). Coagulation diameter and interstitial doxorubicin concentration (tissues were homogenized in acid alcohol, with doxorubicin extracted for 24 hours at 5 degrees C and quantified with fluorimetry) were measured 48 hours after treatment and compared. Multivariate analysis of variance and subsequent pairwise t tests (alpha = .05, two-tailed test) were performed. RESULTS: Data are means +/- standard errors of the mean. A larger diameter of tumor destruction was observed in canine sarcomas treated with RF ablation-liposomal doxorubicin (3.7 cm +/- 0.6) compared with that in tumors treated with RF ablation (2.3 cm +/- 0.1) or liposomal doxorubicin (0.0 cm +/- 0.0) alone (P < .01). A new finding was a completely necrotic red zone (1.6 cm +/- 0.7) surrounding the central RF ablation-induced white coagulation zone. Greater but nonuniform drug uptake was observed particularly in this red zone (77.0 ng/g +/- 18.2) compared with uptake in the central zone (15.1 ng/g +/- 3.2), peripheral area of untreated tumor (38.9 ng/g +/- 8.0), and tumors treated with liposomal doxorubicin alone (43.9 ng/g +/- 6.7 for all regions) (P < .01 for all individual comparisons). In experiment 2, use of combined therapy led to increased coagulation in all tissues (liver: 17.6 mm +/- 3.1, P = .03; kidney: 11.0 mm +/- 3.1, P = .03; muscle: 13.1 mm +/- 1.3, P < .01) compared with use of RF ablation alone (liver, 13.4 mm +/- 1.5; kidney, 7.9 mm +/- 0.7; muscle, 8.6 mm +/- 0.5). Combined therapy, as compared with liposomal doxorubicin therapy alone, was also associated with increased doxorubicin accumulation in liver, kidney, and muscle (1.56 microg/g +/- 0.34, 4.36 microg/g +/- 1.78, and 3.63 microg/g +/- 1.43, respectively, vs 1.00 microg/g +/- 0.18, 1.23 microg/g +/- 0.32, and 0.87 microg/g +/- 0.53, respectively) (P < or = .01 for all individual comparisons). CONCLUSION: Use of RF ablation combined with liposomal doxorubicin facilitates increased tissue coagulation and interstitial doxorubicin accumulation in multiple tissues and tumor types and may be useful for treatment of large tumors and achieving an ablative margin within the untreated tissue surrounding RF ablation-treated tumors.