Automatic quantification of right ventricular volumes and right ventricular ejection fraction with gated blood pool SPECT: Comparison of 8- and 16-frame gated blood pool SPECT with first-pass radionuclide angiography

BACKGROUND: The aim of this study was to compare 8- and 16-frame gated blood pool single photon emission computed tomography (SPECT) (GBPS) for the determination of right ventricular ejection fraction (RVEF) and right ventricular (RV) volumes in subjects who underwent two consecutive GBPS studies. METHODS AND RESULTS: In this study 65 consecutive patients (29 men and 36 women) referred for first-pass radionuclide angiography (FP-RNA) underwent FP-RNA and both 8- and 16-frame GBPS. The mean FP-RNA RVEF was statistically lower than RVEF determined by 8-frame GBPS (P < .001) and 16-frame GBPS (P < .001). Comparison of RVEF by FP-RNA and GBPS yielded coefficients of 0.8666 (P < .0001) for 16-frame GBPS and 0.7290 (P < .0001) for 8-frame GBPS. The correlation of RVEF between 8- and 16-frame GBPS showed a coefficient of 0.6657 (P < .0001). The mean RV end-diastolic volume (EDV) calculated with 8- and 16-frame GBPS showed no statistical differences (P = .3580). The mean RV end-systolic volume (ESV) calculated with 8- and 16-frame GBPS also showed no statistical differences (P = .2265). Comparison of EDV by 8- and 16-frame GBPS yielded a coefficient of 0.7327 (P < .0001). The correlation between ESV by 8-frame GBPS and 16-frame GBPS showed a coefficient of 0.6067 (P < .0001). CONCLUSION: GBPS is a simple and reproducible acquisition method for the assessment of RVEF and RV volumes. RVEF values calculated by 8- and 16-frame GBPS correlated well with FP-RNA, although mean RVEF values from FP-RNA were lower than GBPS RVEF values. In addition, RV ESV and EDV were both well correlated with 8- and 16-frame GBPS. GBPS should prove to be useful in diagnosis, as well as in following disease progression and evaluating the efficacy of therapeutic interventions, in patients with biventricular dysfunction.     

Automatic quantification of right ventricular function with gated blood pool SPECT

BACKGROUND: Quantification of right ventricular (RV) function is clinically relevant for the risk stratification and follow-up of patients with a wide spectrum of disease. This can be achieved with electrocardiography-gated blood pool single photon emission computed tomography (GBPS). We aimed to evaluate the accuracy of the completely automatic QBS GBPS processing software as compared with equilibrium planar radionuclide angiography (RNA) and with a GBPS manual segmentation method (GBPS(35%)) for the measurement of global RV ejection fraction (EF), taking the first-pass RNA (FP-RNA) as the gold standard. In parallel, we compared the RVEF, RV end-diastolic volume (EDV), and RV end-systolic volume (ESV) provided by QBS and GBPS(35%). METHODS AND RESULTS: The population included 85 patients with chronic post-embolic pulmonary hypertension. Twenty-one patients were excluded because of unsuccessful FP-RNA. Intraobserver and interobserver RVEF, RVEDV, and RVESV reproducibilities encountered with planar RNA, QBS, and GBPS(35%) were similar and compared favorably with those calculated with FP-RNA for RVEF. Mean RVEF was different between all methods. RVEF calculated with FP-RNA was better correlated to QBS (r = 0.68) and GBPS(35%) (r = 0.70) than to planar RNA (r = 0.59). RVEDV and RVESV with QBS were lower than with GBPS(35%), by 29% +/- 14% and 36% +/- 13%, respectively. RVEDV and RVESV with QBS were highly correlated to corresponding GBPS(35%) values: r = 0.88 and r = 0.91, respectively. CONCLUSION: As opposed to FP-RNA, GBPS is highly successful for the quantification of RV function. Both QBS and GBPS(35%) provide RVEF values similarly well correlated to FP-RNA and performed better than planar RNA. RVEF, RVEDV, and RVESV provided by QBS and GBPS(35%) are highly correlated. All of these RV functional measurements require further validation versus a better gold standard before their accuracy can be established.     

Quantitative gated blood pool SPECT: Analysis of 3-dimensional models for the assessment of regional myocardial wall motion

BACKGROUND: Gated blood pool single photon emission computed tomography (SPECT) (GBPS) uses truly 3-dimensional (3D) data, requiring attention to appropriate reference systems and segmentation models for proper quantification. To date, optimal 3D reference models have not been evaluated. In this study several techniques for 3D GBPS were evaluated. METHODS AND RESULTS: Static and dynamic cardiac phantom evaluations were performed, and GBPS studies for 3 healthy subjects and 9 patients were processed by a variety of 3D analysis techniques to determine the optimum parameters for identification of abnormal segments when compared with coronary arteriography and left ventriculography. Left ventricular wall motion was quantified by calculation of regional ejection fraction (rEF) through use of count, volume, and cord length changes from end diastole to end systole. Three contractile models were evaluated: (1) fixed center of mass (COM), (2) floating COM, and (3) a modification of the method developed by Slager et al (J Am Coll Cardiol 1986;7:317-26), based on the motion of implanted endocardial markers. Eight, twelve, and eighteen 3D segments were analyzed by means of the 3 contractile models and correlated against coronary artery disease assessed by coronary arteriography. Single-head gamma-camera acquisition provided adequate counting statistics to reliably compute rEF for up to 18 left ventricular segments. Using count changes the overall results were able to identify myocardium supplied by diseased coronary arteries when compared with coronary arteriography. Cord length and, to a lesser degree, volume changes provided somewhat poorer sensitivities and specificities when compared with rEF computed from regional count changes, as compared with coronary arteriography. CONCLUSIONS: Three-dimensional quantitative GBPS appears to be a sensitive method for assessing wall motion defects due to coronary artery disease.     

Comparison between ECTb and QGS for assessment of left ventricular function from gated myocardial perfusion SPECT

BACKGROUND: The most widely distributed software packages to compute left ventricular (LV) volume and ejection fraction (EF) from gated perfusion tomograms are QGS and the Emory Cardiac Toolbox (ECTb). Because LV modeling and time sampling differ between the algorithms, it is necessary to document relationships between values produced by them and to establish normal limits individually for each software package in order to interpret results obtained for individual patients. METHODS AND RESULTS: Gated single photon emission computed tomography technetium 99m sestamibi myocardial perfusion studies were collected and analyzed for 246 patients evaluated for coronary artery disease. QGS and ECTb values of ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume were found to correlate linearly (r = 0.90, 0.91, and 0.94, respectively), but EF and EDV were significantly lower for QGS than with ECTb (53% +/- 13% vs 61% +/- 13 and 102 +/- 45 mL vs 114 +/- 50 mL, respectively). To compare calculations for healthy subjects between the two software packages, data were also selected for 50 other patients at low likelihood for coronary artery disease, for whom EF and EDV were significantly lower for QGS compared with ECTb (62% +/- 9% vs 67% +/- 8% and 84 +/- 26 mL vs 105 +/- 33 mL, respectively). The ECTb lower limit was 51% for EF and the upper limits were 171 mL for EDV and 59 mL/m(2) for mass-indexed EDV, compared with limits of 44%, 137 mL, and 47 mL/m(2) for QGS. CONCLUSIONS: Although correlations were strong between the two methods of computing LV functional values, statistical scatter was substantial and significant biases and trends observed. Therefore, when both software packages are used at the same site, it will be important to take these differences into consideration and to apply normal limits specific to each set of algorithms.     

Comparison of left ventricular contraction homogeneity index using SPECT gated blood pool imaging and planar phase analysis

Background  There is growing interest in developing a practical technique to accurately assess ventricular synchrony. We describe a novel 3-dimensional (3D) gated blood pool single photon emission computed tomography (SPECT) approach, from which a contraction homogeneity index (CHI) is derived and compared with planar phase analyses. Methods and Results  Subjects underwent planar and SPECT blood pool acquisition. Planar images were processed for left ventricular ejection fraction computation and phase values. SPECT images were processed by our novel algorithm, with which CHI was computed. Overall, 235 patients (79% male; mean age, 62±11 years) completed the study. Left ventricular ejection fractions were similar by planar (33.5%±13.5%) and 3D (34.7%±12.7%) methods (r=0.83, P<.0001). Mean phase angles for planar and tomographic methods were 126.3°±29.6° and 124.4°±28.7°, respectively (r=0.53, P<.0001). Phase and amplitude signals were incorporated in the CHI, which was non-normally distributed with a median of 73.8% (interquartile range, 58.7%–84.9%). This index minimized the negative impact of dyskinetic wall segments with limited regional motion. The planar heterogeneity index (SDΦ) was 28.2° (interquartile range, 17.5°–46.8°) and correlated inversely with CHI (r=−0.61, P<.0001). Conclusion  The novel 3D dispersion index CHI accounts for both phase delay of a dyssynchronous segment and its magnitude of contraction and is moderately correlated with planar phase analyses. Its potential in cardiac resynchronization therapy remains to be exploited. This work was supported in part by the “Fonds de la Recherche en Santé du Québec” and by a Canada Research Chair.     

Comparative study of quantitative blood pool SPECT imaging with 180° and 360° acquisition orbits on accuracy of cardiac function

BACKGROUND: Quantitative blood pool single photon emission computed tomography (SPECT) (QBS) can measure ejection fraction (EF) and volumes from gated blood pool single photon emission tomography (GBPS) working in fully automatic mode in 3-dimensional space. The effects of 180 degrees and 360 degrees data acquisition in GBPS have not been fully evaluated. This study compares the accuracy of 360 degrees and 180 degrees data acquisition for left ventricular (LV) systolic function in a clinical study and measures LV volume by GBPS compared with ultrasound echocardiography. METHODS AND RESULTS: The study population comprised 9 normal volunteers and 34 patients. GBPS data were acquired by use of 360 degrees rotation and 60 stops per head. All 60 (360 degrees ) and 30 (45 degrees right anterior oblique to 45 degrees left posterior oblique) pieces of projection data that were selected for reconstructing the 180 degrees data were reconstructed and both ventricular functional parameters were automatically obtained by QBS software. The contour of the LV septal wall was concave in 6 patients (14%) when processed at 180 degrees , whereas a concave septum at 360 degrees processing was observed in only 1 patient (2%). The coefficients of correlation between 180 degrees and 360 degrees were 0.467 for the end-diastolic volume (EDV) and 0.648 for the end-systolic volume (ESV). The mean 180 degrees EDV value (152.9 +/- 46.1 mL) was significantly smaller than that of the 360 degrees EDV (191 +/- 70.8 mL) ( P < .001). However, there was no significant difference between the 360 degrees EDV (0.623) and 180 degrees EDV (0.407) as compared by echocardiography ( P = .218). The agreement of the EF between both methods was close ( r = 0.894, P < .0001). The agreement of the right ventricular volumes between the 180 degrees and 360 degrees orbits was close ( r = 0.800 for EDV and 0.706 for ESV). The EF was relatively dispersed between the 180 degrees and 360 degrees methods ( r = 0.642). CONCLUSION: This study showed that SPECT image acquisition by use of both the 180 degrees method and the 360 degrees method considerably underestimated LV volume quantification. In addition, the LV volume with the 180 degrees method was significantly smaller than that with the 360 degrees method. Thus a 360 degrees acquisition orbit may be suitable for more quantitatively accurate results when blood pool imaging is performed with gated SPECT.     

SPECT versus planar gated blood pool imaging for left ventricular evaluation

Background  We developed a new segmentation algorithm based on the invariance of the laplacian (IL) to compute volumes and ejection fractions and compared these results with planar analysis and gradients by use of a standard algorithm (QBS). Methods and Results  Planar and single photon emission computed tomography blood pool acquisition was performed in 202 patients. Planar left ventricular ejection fraction (LVEF) was used as the gold standard, and single photon emission computed tomography images were processed by both 3-dimensional (3D) methods. Correlations between each 3D algorithm and planar methodology were as follows:r=0.77 for QBS andr=0.84 for IL. Mean LVEFs were 32.72%±13.05% for the planar method, 32.32%±15.98% for QBS, and 31.93%±13.44% for IL (P=.16). Bland-Altman analysis closely demonstrated negligible systematic bias for both 3D methods. Standard errors of bias were comparable between methods (9.36% for QBS and 7.44% for IL,P=.48). Linear regression of the Bland-Altman bias revealed a slope significantly different from 0 for the QBS method (0.22±0.048,P<.0001) but not for IL (−0.032±0.0044,P=.47). Conclusion  The new segmentation algorithm provides comparable results to QBS and planar analysis. However, with QBS, the difference in LVEF was correlated with the magnitude of LVEF, which was not found with the new algorithm.     

Clinical impact of arrhythmias on gated SPECT cardiac myocardial perfusion and function assessment

BACKGROUND. We reported previously that mean quantified cardiac functional parameters computed by one gated single photon emission computed tomography (SPECT) technique were not significantly altered by common gating errors. However, it is not known to what extent other gated SPECT approaches that are based on different ventricular modeling assumptions are influenced by arrhythmias, nor are the effects of gating errors on visual analyses and their subsequent clinical implications known. METHODS. Projection data for 50 patients (aged 64 +/- 12 years; 68% men; 76% with myocardial perfusion defects) undergoing technetium-99m sestamibi gated SPECT who were in sinus rhythm during data acquisition were altered to simulate common arrhythmias. To determine quantitative effects, we performed calculations for original control and altered images by Gaussian myocardial detection (Quantitative Gated SPECT [QGS] program) and by wall thickening derived from gated perfusion polar maps (Emory Cardiac Toolbox program). To evaluate visual assessment in control and simulated-arrhythmia tomograms, 2 experienced blinded observers independently interpreted perfusion from polar maps and wall motion and thickening from tomographic cines, using a 4-point scale. RESULTS. Although mean functional parameters were scarcely altered, paired t tests showed ejection fraction fluctuations to be significantly different from control values, causing patients to change between abnormal and normal ejection fraction categories (2% of patients by QGS and 14% by Emory Cardiac Toolbox). Visual examination of QGS polar perfusion and function maps showed changes for 72% of cases, although in only 4% were these considered to have potential clinical consequences. The kappa statistic for visual analysis of concordance between control and arrhythmia readings showed that agreement was "excellent" for perfusion, "good" for motion, and "marginal" for thickening. CONCLUSIONS. As with quantitative measurements, thickening is the parameter most prone to error in the presence of arrhythmias. It is important to test data for gating errors to avoid potentially erroneous measurements and visual readings.     

Multicenter intercomparison assessment of consistency of left ventricular function from a gated cardiac SPECT phantom

Background  A multicenter intercomparison assessment was made of the variation in left ventricular (LV) volumes and ejection fractions (EFs) obtained from gated myocardial perfusion single photon emission computed tomography (SPECT) of the 3-dimensional AGATE (Amsterdam gated) cardiac phantom. Methods and Results  The phantom was configured to produce 3 different standard end-systolic volume and end-diastolic volume combinations (50 mL and 120 mL, 90 mL and 160 mL, and 120 mL and 190 mL) with corresponding EF (58%, 44%, and 37%). Quantitative gated myocardial perfusion SPECT was performed with 39 SPECT systems in 35 departments. In the multicenter study, for all 3 filling conditions, a wide range of results was obtained. The EF was overestimated (by 1% to 15%), and both the end-systolic volume and end-diastolic volume were underestimated (by 1 to 65 mL). The extent of overestimation of EF was related to the extent of underestimation of the volumes and was independent of filling condition. The trend in error per center was comparable for all 3 filling conditions. Acquisition time per projection was the only independent predictor of the difference between measured and expected EF (P = .0001). Conclusions  Care should be taken before extrapolation of published and accepted cutoff values for LV EF and volumes in clinical decision making. Results should be validated in each center and monitored for accuracy and consistency over time.     

Comparison of gated N-13 ammonia PET and gated Tc-99m sestamibi SPECT for quantitative analysis of global and regional left ventricular function

Background  The aim of this study was to compare global and regional left ventricular function in patients with coronary artery disease (CAD), obtained by use of Cedars-Sinai quantitative gated single photon emission computed tomography (QGS), for gated nitrogen 13 ammonia (NH₃) positron emission tomography (PET) and technetium 99m sestamibi (MIBI) single photon emission computed tomography (SPECT). Methods and Results  Fifty-one patients with CAD underwent gated N-13 NH₃ PET and gated MIBI SPECT. The end-diastolic volume, end-systolic volume, and ejection fraction were calculated by use of QGS. The quantitative regional wall motion (WM) and wall thickening (WT) scores for 20 segments in the myocardium were also measured by QGS. The end-diastolic volume, end-systolic volume, and ejection fraction measured by N-13 NH₃ PET showed highly significant correlation with those measured by MIBI SPECT (r=0.97, r=0.97, and r=0.84, respectively). The mean correlation of WM and WT on an individual patient basis between N-13 NH₃ PET and MIBI SPECT was 0.81 and 0.84, respectively. The circumferential variation of WM and TT in 20 segments showed a similar pattern with N-13 NH₃ PET and MIBI SPECT. Conclusion  Gated N-13 NH₃ PET combined with QGS provides information on both global and regional left ventricular function comparable to that obtained by gated Tc-99m perfusion myocardial SPECT in CAD patients.     

Parametric phase display for biventricular function from gated cardiac blood pool single-photon emission tomography

Complete assessment of biventricular function from planar ECG-gated cardiac blood pool studies has been limited because of the overlap of adjacent activity-containing structures. Theoretically, single-photon emission tomography (SPET) can be used to comprehensively evaluate both ventricles by isolating them from surrounding anatomy. However, an enormous amount of parametric data is generated from gated SPET studies, and much of it is diagnostically irrelevant for ventricular wall motion analysis. To compress this information to a more easily interpretable format, a two-dimensional parametric display has been developed. Fourier analysis of short-axis tomograms from a gated cardiac blood pool SPET study generates three-dimensional, first-harmonic phase data. Circumferential profile data from the parametric tomograms of the right and left ventricle are mapped onto a two-dimensional polar display. This method is demonstrated in a normal patient and in three patients with abnormal ventricular contraction patterns and appears to have potential application for the analysis and characterization of biventricular wall motion. Correspondence to: D.R. Neumann     

Stress-related variations in left ventricular function as assessed with gated myocardial perfusion SPECT

BACKGROUND: There is inconsistency in reported patient characteristics associated with differences in basal and poststress left ventricular function (delta ejection fraction [DeltaEF]) assessed by gated single photon emission computed tomography (SPECT). This inconsistency may therefore hamper adequate interpretation. In this study we first determined the reproducibility of serial gated SPECT-assessed left ventricular function. Second, we determined whether left ventricular ejection fraction (LVEF) assessed directly after stress reflects basal LVEF and, if not, what patient characteristics were associated with this discrepancy in LVEF. METHODS AND RESULTS: Serial reproducibility of technetium 99m tetrofosmin gated SPECT-assessed LVEF in 22 patients showed a mean difference between two sequential measurements at rest of 0.09% EF units, with a 95% limit of agreement (2 SDs) at 5.8% EF units. In 229 patients Tc-99m tetrofosmin gated SPECT was performed after stress and at rest. Independent predictors of DeltaEF were the presence of scintigraphically proven ischemia (standardized coefficient, -1.256; P =.003) and difference in heart rate at the time of acquisition (standardized coefficient, 0.121; P =.001). CONCLUSIONS: Gated SPECT-assessed LVEF at rest is reproducible under standard clinical conditions. However, LVEF assessed after stress does not represent LVEF at rest in patients with scintigraphically proven ischemia and in patients with increased heart rate after stress compared with heart rate at rest.     

Prognostic value of poststress left ventricular volume and ejection fraction by gated myocardial perfusion SPECT in women and men: Gender-related differences in normal limits and outcomes

Background  Whether there are gender differences in the prognostic application of gated myocardial perfusion single photon emission computed tomography (SPECT) has not been assessed. asMethods and Results Gender-specific normal limits of poststress volume and ejection fraction (EF) were obtained in 597 women and 824 men with a low likelihood of coronary artery disease and normal perfusion and were applied in a prognostic evaluation of 6713 patients (2735 women and 3978 men). Patients underwent rest thallium-201/stress technetium-99m sestamibi gated myocardial perfusion SPECT and were followed up for 35 ± 14 months. The upper limit of the end-systolic volume (ESV) index was 27 mL/m2 in women and 39 mL/m2 in men, and the upper limit of the end-diastolic volume index was 60 mL/m2 in women and 75 mL/m2 in men. The lower limit of the EF was 51% in women and 43% in men. Gated SPECT variables provided incremental prognostic information in both genders. Women with severe ischemia and an EF lower than 51% or an ESV index greater than 27 mL/m2 were at very high risk of cardiac death or myocardial infarction (3-year event rates of 39.8% and 35.1%, respectively), whereas women with severe ischemia but an EF of 51% or greater or an ESV index of 27 mL/m2 or less were at intermediate or high risk (3-year event rates of 10.8% and 15.2%, respectively). Conclusion  Poststress EF and ESV index by gated myocardial perfusion SPECT provide comparable incremental prognostic information over perfusion in women and men. After separate criteria for abnormal EF and ESV index in women are used, the combination of severe ischemia and abnormal EF or ESV index identifies women at very high risk of cardiac events. Partial funding was provided by grants from Bristol-Myers Squibb Medical Imaging, Inc, Billerica, Mass, and Astellas Pharma US, Inc, Deerfield, Ill.     

Compared with 3-dimensional analysis, 2-dimensional gated SPECT analysis overestimates left ventricular ejection fraction in patients with regional dyssynchrony

BACKGROUND: Left ventricular (LV) ejection fraction (EF) is a powerful prognostic predictor in patients with heart disease. However, LVEF calculated by 2-dimensional (2D) modalities such as echocardiography by use of the "modified" Simpson's rule may be incorrect in patients with regional dyssynchrony, presumably because regions of dyssynchrony are excluded from analysis. METHODS AND RESULTS: To elucidate the difference between 2D and 3-dimensional (3D) methods with regard to LVEF calculation in patients with regional dyssynchrony, we compared LVEF derived from 8-frame gated technetium 99m sestamibi stress perfusion tomograms using commercially available 2D single photon emission computed tomography (SPECTEF) software that uses the modified Simpson's rule, 3D QGS, and investigational 3D p-FAST software in 136 left bundle branch block patients. Twenty-four patients had normal wall motion, whereas one hundred twelve showed septal dyssynchrony. Bland-Altman plots demonstrated that compared with QGS and p-FAST, SPECTEF overestimated LVEF in patients with septal dyssynchrony systemically by 8.6% and 11.3%, respectively. CONCLUSIONS: We conclude that compared with 3D modalities, 2D modalities that use the modified Simpson's rule, such as SPECT EF, overestimate LVEF in patients with dyssynchronous septal wall motion. Therefore 3D modalities are preferred to evaluate patients with regional dyssynchrony.     

Left ventricular ejection fraction and volumes from gated blood pool tomography: Comparison between two automatic algorithms that work in three-dimensional space

BACKGROUND: Two different algorithms, which are fast and automatic and which operate in 3-dimensional space, were compared in the same group of patients to compute left ventricular ejection fraction (LVEF) and volumes from gated blood pool tomography. One method, developed at Cedars-Sinai Medical Center (CS), was dependent on surface detection, whereas the other method, developed at the Free University of Brussels (UB), used image segmentation. METHODS AND RESULTS: Gated blood pool tomograms were acquired in 92 consecutive patients after injection of 740 MBq of technetium 99m-labeled human serum albumin. After reconstruction and reorientation according to the left ventricular long axis, LVEF and left ventricular volumes were measured with the CS and UB algorithms. Measurements of LVEF were validated against planar radionuclide angiocardiography (PRNA) results. The success rates of the algorithms were 87% for CS and 97% for UB. Agreement between LVEF measured with CS and UB (LVEF(CS) = 0.91. LVEF(UB) - 0.85; r = 0.87) and between LVEF measured with CS and PRNA (LVEF(CS) = 1.04. LVEF(PRNA) - 4.75; r = 0.80) and UB and PRNA (LVEF(UB) = 0.98. LVEF(PRNA) + 4.42; r = 0.82) was good. For left ventricular volumes, linear regression analysis showed good correlation between both methods with regard to end-diastolic volumes (r = 0.81) and end-systolic volumes (r = 0.91). On average, end-diastolic volumes were similar and end-systolic volumes were slightly higher with CS than with UB. Consequently, significantly lower LVEFs were observed with CS than with UB. CONCLUSIONS: Good correlation was observed between CS and UB for both left ventricular volumes and ejection fraction. In addition, measurements of LVEF obtained with both algorithms correlated fairly well with those obtained from conventional PRNA over a wide range of values.     

Comparison of interstudy reproducibility of equilibrium electrocardiography-gated SPECT radionuclide angiography versus planar radionuclide angiography for the quantification of global left ventricular function

BACKGROUND: Electrocardiography-gated single photon emission computed tomography (SPECT) radionuclide angiography (RNA) provides accurate measurement of both left ventricular (LV) ejection fraction (EF) and end-diastolic and end-systolic volumes. In this study we studied the interstudy precision and reliability of SPECT RNA as compared with planar RNA for the measurement of global systolic LV function. METHODS AND RESULTS: The population included 10 patients with chronic coronary artery disease having 2 sets of acquisitions, each consisting of planar and SPECT RNA. SPECT RNA was processed with SPECT-QBS and SPECT-35%. (For SPECT-35%, a manual segmentation method based on the 35% threshold of the maximum LV cavity activity is used to provide estimates of the number of voxels and the activity included in the LV cavity. The calculated LV number of voxels is then used to calculate LV volume measurement. The LV EF is calculated as the ratio of LV end-diastolic and end-systolic activity.) For LV EF, end-diastolic volume, and end-systolic volume, the interstudy precision, as reflected by the correlation coefficient, coefficient of variability, coefficient of repeatability, and within-subject coefficient of variation, and the interstudy reliability, as reflected by the intraclass correlation coefficient, were best with SPECT-35%, followed by planar RNA and then SPECT-QBS, respectively. The sample size needed to objectify a change in a parameter of LV function is lowest with SPECT-35%, followed by planar RNA and then SPECT-QBS, respectively. CONCLUSIONS: The SPECT-35% processing method provides excellent interstudy precision and reliability for LV function measurement. In this aspect it seems to be better than planar RNA and SPECT-QBS. These results need to be confirmed in a larger patient population.     

Myocardial contractile reserve determined by dobutamine stress Tc-99m tetrofosmin quantitative gated SPECT predicts late spontaneous improvement in cardiac function in patients with recent-onset dilated cardiomyopathy

BACKGROUND: We evaluated whether dobutamine stress technetium 99m tetrofosmin (DSTF) quantitative gated single photon emission computed tomography (QGS) could predict late spontaneous improvement of cardiac function in patients with idiopathic dilated cardiomyopathy (DCM). METHODS AND RESULTS: The study included 26 patients with recently diagnosed (<2 months) idiopathic DCM and a left ventricular ejection fraction (LVEF) lower than 45%. DSTF-QGS was performed in all patients to measure LVEF at rest and during dobutamine infusion (10 microg. kg(-1). min(-1)). LVEF and left ventricular end-diastolic volume (LVEDV) were determined by echocardiography, and New York Heart Association (NYHA) functional class was estimated at baseline and after 1 year. After 1 year of treatment, the echocardiographic LVEF improved by greater than 5% in 13 patients (group A) but did not improve in the remaining 13 patients (group B). At baseline, the echocardiographic LVEF, LVEDV, and NYHA functional class were similar in both groups. However, there was a greater increase in the LVEF during the dobutamine infusion portion of the DSTF-QGS (DeltaLVEF) in group A than in group B (13.1% +/- 5.9% vs 2.6% +/- 4.1%, P <.0001). If a critical value for the DeltaLVEF of 7.0% was used to predict improvement in LVEF after treatment, the sensitivity was 84.7% and the specificity was 84.7%. LVEDV and NYHA functional class improved to a greater extent in group A than in group B. CONCLUSIONS: DSTF-QGS can be used to predict late spontaneous improvement in cardiac function and symptoms after treatment in patients with idiopathic DCM.     

Comparison of two three-dimensional gated SPECT methods with thallium in patients with large myocardial infarction

BACKGROUND: Two different commercially available gated single photon emission computed tomography (GSPECT) methods were compared in a population of patients with a major myocardial infarction. METHODS: Rest thallium GSPECT was performed with a 90-degree dual-detector camera, 4 hours after injection of thallium-201 (Tl-201; 185 MBq) in 43 patients (mean age, 62+/-12 years) with a large myocardial infarction (mean defect size, 33%+/-16%). End-diastolic volume (EDV), end-systolic volume (ESV), and left ventricular ejection fraction (LVEF) were calculated by using QGS (Cedars Sinai) and MultiDim (Sopha Medical Vision International, Buc, France). Images were reconstructed by using a 2.5 zoom and a Butterworth filter (order, 5; cut-off frequency, 0.20). LVEF was calculated in all patients by using equilibrium radionuclide angiocardiography (ERNA). EDV, ESV, and LVEF were also measured by using left ventriculography (LVG). RESULTS: Compared with LVG, QGS underestimated LVEF by means of an underestimation of mean EDV. MultiDim overestimated EDV and ESV. GSPECT EDV and ESV overestimation was demonstrated by means of Bland-Altman analysis to increase with left ventricular volume size (P<.05). The difference between LVG and GSPECT volumes was demonstrated by means of regression analysis to be correlated with infarction size. This effect was particularly important with MultiDim (P<.0001). CONCLUSION: In Tl-201 GSPECT, LVEF and volume measurements will vary according to the type of software used.     

Automatic quantification of left ventricular ejection fraction from gated blood pool SPECT

BACKGROUND: Cardiac gated blood pool single photon emission computed tomography (GBPS) better separates cardiac chambers compared with planar radionuclide ventriculography (PRNV). We have developed a completely automatic algorithm to measure quantitatively the left ventricular ejection fraction (LVEF) from gated technetium 99m-red blood cells (RBC) GBPS short-axis 3-dimensional image volumes. METHODS AND RESULTS: The algorithm determines an ellipsoidal coordinate system for the left ventricle and then computes a static estimate of the endocardial surface by use of counts and count gradients. A dynamic surface representing the endocardium is computed for each interval of the cardiac cycle by use of additional information from the temporal Fourier transform of the image data sets. The algorithm then calculates the left ventricular volume for each interval and computes LVEF from the end-diastolic and end-systolic volumes. The algorithm was developed in a pilot group (N = 45) and validated in a second group (N = 89) of patients who underwent PRNV and 8-interval GBPS. Technically inadequate studies (N = 38) were rejected before grouping and processing. Automatic identification and contouring of the left ventricle was successful in 121/172 patients (70%) globally and in 76/89 patients (85 %) in the validation group. Correlation between LVEFs measured from GBPS and PRNV was high (y = 2.00 + 1.01x, r = 0.89), with GBPS LVEF significantly higher than PRNV LVEF (average difference = 2.8%, P < .004). CONCLUSIONS: Our automatic algorithm agrees with conventional radionuclide measurements of LVEF and provides the basis for 3-dimensional analysis of wall motion.     

The additive prognostic value of perfusion and functional data assessed by quantitative gated SPECT in women

Background  The aim of this study was to assess the prognostic value of technetium-99m tetrofosmin gated SPECT imaging in women using quantitative gated single photon emission computed tomography (SPECT) imaging. Methods  We followed 453 consecutive female patients. Average follow-up was 1.33 years (max. 2.55). Hard endpoints were cardiac death, acute myocardial infarction, or documented ventricular fibrillation. Event-free survival curves were obtained. Optimal cutoff values for left ventricular (LV) volumes, LV ejection fraction (LVEF), and perfusion data to predict outcome were determined by ROC curve analysis. Results  A total of 236 patients had an abnormal study, of whom 27 patients experienced hard events (16 deaths) and 47 patients soft events. For hard events summed stress score (SSS) and LVEF, and for any cardiac event SSS showed independent incremental prognostic value. The survival curves were maximally separated when using cutoff values for SSS of ≥22 and LVEF < 52% (P < 0.001, HR 4.61 and P < 0.001 HR 5.24 for SSS and LVEF resp.), and SSS ≥ 14 (P < 0.001 HR 3.76) for any cardiac event. Conclusion  In women, perfusion and functional parameters derived from quantitative gated technetium-99m tetrofosmin SPECT imaging can adequately be used for cardiac risk assessment. Using quantitative gated SPECT, female patients with an LVEF < 52% or an SSS ≥ 22 are at increased risk for subsequent hard events. Furthermore, patients with an SSS ≥ 14 are at increased risk for any cardiac events.