Quantitative Gated SPECT Research Articles

Evaluation of left ventricular volumes and ejection fraction by gated SPECT and cardiac MRI in patients with dilated cardiomyopathy

The goal of this study was to evaluate the accuracy of gated single photon emission computed tomography (SPECT) in the assessment of left ventricular (LV) end-diastolic/end-systolic volumes (EDV, ESV) and ejection fraction (LVEF) in patients with dilated cardiomyopathy, using cardiac magnetic resonance imaging (MRI) as the reference method. Furthermore, software-specific characteristics of Quantitative Gated SPECT (QGS), Emory Cardiac Toolbox (ECTB) and 4D-MSPECT were analysed. Thirty-six patients with dilated cardiomyopathy who underwent gated (99m)Tc-methoxyisobutylisonitrile SPECT and cardiac MRI were included. LV EDV, ESV and LVEF values of gated SPECT were calculated using QGS, ECTB and 4D-MSPECT. The correlation between the results of gated SPECT and cardiac MRI was excellent for EDV [R = 0.872 (QGS), R = 0.879 (ECTB), R = 0.869 (4D-MSPECT)], ESV [R = 0.908 (QGS), R = 0.897 (ECTB), R = 0.880 (4D-MSPECT)] and LVEF [R = 0.794 (QGS), R = 0.763 (ECTB), R = 0.710 (4D-MSPECT)]. EDV and ESV assessed by QGS did not differ significantly from those assessed by cardiac MRI (all p = NS), whereas EDV and ESV were overestimated by ECTB and 4D-MSPECT compared with cardiac MRI (all p < 0.05). LVEF was overestimated by QGS, ECTB and 4D-MSPECT compared with cardiac MRI (all p < 0.05). The correlation between gated SPECT and cardiac MRI is excellent for LV volume and LVEF values calculated by QGS, ECTB and 4D-MSPECT in patients with dilated cardiomyopathy. However, algorithm-varying over- or underestimation of LV volumes and LVEF should be accounted for in the clinical context.

Gated myocardial perfusion SPECT for preoperative risk stratification in patients with noncardiac vascular disease

Myocardial perfusion single photon emission computed tomography (SPECT) is useful for preoperative cardiac risk stratification. We investigated the value of preoperative pharmacologic stress electrocardiographic (ECG)-gated myocardial perfusion SPECT for noncardiac vascular surgery. To assess the perioperative cardiac risk for noncardiac vascular surgery, preoperative pharmacologic stress ECG-gated myocardial perfusion SPECT was performed in 211 consecutive patients who underwent noncardiac aortic surgery. We examined myocardial perfusion and left ventricular function by the quantitative gated SPECT (QGS), and the correlation with perioperative cardiac events was investigated. Perioperative cardiac events occurred in 9 of 211 patients (4.3%). On the basis of univariate analysis, significant predictors for preoperative cardiac risk stratification included history of heart failure (P < 0.05), history of coronary artery revascularization (P < 0.05), summed stress score (SSS) (P < 0.0001), summed rest score (SRS) (P < 0.005), SSS > or = 7 (P < 0.005), end-diastolic volume (EDV) > or = mean + 2 standard deviation (SD) (134 ml for men and 93 ml for women) (P < 0.005), end-systolic volume (ESV) > or = mean + 2 SD (60 ml for men and 37 ml for women) (p < 0.0001), left ventricular ejection fraction (EF) < or = mean - 2 SD (48% for men and 55% for women) (P < 0.005) and wall motion abnormality (P < 0.05). On the basis of multivariate analysis, ESV > or = mean + 2 SD was the only independent predictor for perioperative cardiac events (P < 0.005). Pharmacologic stress ECG-gated myocardial perfusion SPECT, which permits assessment of both myocardial perfusion and cardiac function, is useful for preoperative risk stratification of noncardiac vascular surgery.

Abstract 729: A More Accurate Method for Automatic Segmentation of Left Ventricular Mass by SPECT

Background: Accurate quantification of left ventricular mass (LVM) by single photon emission computed tomography (SPECT) is important when analysing LVM as such, but also when estimating the relative size of a perfusion defect. Existing algorithms for segmentation of LVM by SPECT have undergone limited validation. The aim of this study was to develop and validate a new segmentation algorithm for LVM by SPECT, and compare the new method to the commercially available software Quantitative Gated SPECT (QGS). Methods: 98 patients with known or suspected coronary artery disease underwent both rest and stress SPECT and MR. The new method was trained in 20 patients (40 studies) and tested in 78 patients (156 studies) by comparing LVM in both rest and stress SPECT with manually segmented LVM by magnetic resonance imaging (MRI) as the reference standard. The new method was compared to results from QGS. Results: The mean difference ±SD in LVM between SPECT and MRI was lower for the new method (6±15 %LVM) compared to QGS (18±19 %LVM) for both mean difference (p&lt;0.001, t test) and SD (p=0.01, F test), see Figure . Conclusion: The new method quantifies LVM with a significantly lower bias and variability compared to the commercially available QGS software, when compared to manually segmented LVM by MRI.

Clinical significance of diastolic function as an indicator of myocardial ischemia assessed by 16-frame gated myocardial perfusion SPECT

Studies have suggested that ischemia-induced diastolic dysfunction persists longer than systolic dysfunction. We examined whether global left ventricular (LV) diastolic function during stress testing assessed by 16-frame gated myocardial perfusion single-photon emission computed tomography (SPECT) is useful as an indicator of myocardial ischemia. Thirty-nine patients underwent 16-frame technetium-99m (Tc-99m) quantitative gated SPECT (QGS), including treadmill exercise testing for suspected ischemic heart disease. Diastolic parameters of the first-third filling fraction (1/3FF), and the peak filling rate (PFR) were calculated by a time-volume curve from the QGS data. The patients were divided into four groups, namely, IS, NL, DN, and DD, on the basis of tracer accumulation and the LV ejection fraction (LVEF) at rest. In the IS group (reversible tracer uptake reduction suggesting ischemia; n=11), LVEF, 1/3FF, and PFR after stress were significantly lower than those at rest, whereas in the NL group (normal perfusion; n=10) and DN group (fixed tracer uptake reduction with normal systolic function; EF>or=60% at rest; n=10), LVEF, 1/3FF, and PFR after stress did not differ from those at rest. However, in the DD group (fixed tracer uptake reduction with cardiac dysfunction; EF<60%, average 47.1%; n=8), LVEF, 1/3FF, and PFR were significantly altered after stress. Altered global LV diastolic function during stress assessed by 16-frame gated myocardial perfusion SPECT is useful for the detection of myocardial ischemia. However, similar findings are observed in patients with cardiac dysfunction but without detectable ischemia. Our findings do suggest that tests should be performed with caution to determine whether ischemia exists on the basis of altered global LV function after stress in patients with cardiac dysfunction.

Gated Myocardial Perfusion SPECT: Algorithm-Specific Influence of Reorientation on Calculation of Left Ventricular Volumes and Ejection Fraction

Gated myocardial perfusion SPECT allows calculation of end-diastolic and end-systolic volumes (EDV and ESV, respectively) and left ventricular ejection fraction (LVEF). The quantification algorithms QGS (quantitative gated SPECT), 4D-MSPECT, and CARE heart show a good correlation with cardiac MRI. Nevertheless, differences in contour finding suggest algorithm-specific effects if heart axes vary. The effect of tilting heart axes on gated SPECT was quantified as a possible source of error. Sixty men underwent gated SPECT (450 MBq of (99m)Tc-tetrofosmin or sestamibi, 8 gates/cycle). After correct reorientation (R(0)), datasets were tilted by 5 degrees , 10 degrees , 15 degrees , 20 degrees , 30 degrees , and 45 degrees along both long axes (R(5), R(10), R(15), R(20), R(30), and R(45), respectively). EDV, ESV, and LVEF were calculated using QGS, 4D-MSPECT, and CARE heart. Because a 15 degrees tilt could be a maximum possible misreorientation in routine, R(0) and R(15) results were analyzed in detail. Absolute-difference values between results of tilted and correctly reoriented datasets were calculated for all tilts and algorithms. QGS and CARE heart succeeded for R(0) and R(15) in all cases, whereas 4D-MSPECT failed to find the basal plane in 1 case (patient B). R(2) values between paired R(15)/R(0) results were 0.992 (QGS), 0.796 (4D-MSPECT; R(2) = 0.919 in n = 59 after exclusion of the failed case), and 0.916 (CARE heart) for EDV; 0.994 (QGS), 0.852 (4D-MSPECT; R(2) = 0.906 in n = 59), and 0.899 (CARE heart) for ESV; and 0.988 (QGS), 0.814 (4D-MSPECT; R(2) = 0.810 in n = 59), and 0.746 (CARE heart) for LVEF. Concerning all levels of misreorientation, 1 patient was excluded for all algorithms because of multiple problems in contour finding; additionally for 4D-MSPECT patient B was excluded. In the 45 degrees group, QGS succeeded in 58 of 59 cases, 4D-MSPECT in 58 of 58, and CARE heart in 33 of 59. Mean absolute differences for EDV ranged from 5.1 +/- 4.1 to 12.8 +/- 10.5 mL for QGS, from 6.7 +/- 6.3 to 34.2 +/- 20.7 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.2 +/- 16.1 mL for CARE heart (tilts between 5 degrees and 45 degrees ). Mean absolute differences for ESV ranged from 4.1 +/- 3.7 to 8.0 +/- 9.4 mL for QGS, from 5.6 +/- 8.0 to 10.0 +/- 10.5 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.5 +/- 16.1 mL for CARE heart. Mean absolute differences for LVEF ranged from 1.1% +/- 1.0% to 2.2% +/- 1.8% for QGS, from 4.0% +/- 3.5% to 8.0% +/- 7.1% for 4D-MSPECT, and from 3.4% +/- 2.9% to 9.2% +/- 6.0% for CARE heart. Despite tilted heart axes, QGS showed stable results even when using tilts up to 45 degrees . 4D-MSPECT and CARE heart results varied with reorientation of the heart axis, implying that published validation results apply to correctly reoriented data only.

Evaluation of new automated gated-SPECT and echocardiographic methods for calculating left ventricular volumes and ejection fraction

Background Left ventricular (LV) volumes and ejection fraction (LVEF) are assessed using ECG-gated myocardial perfusion scintigraphy (MPS) and echocardiography. We have developed CAFU, a new automated method for the quantification of MPS images. AutoEF software is a new automated method for quantifying echocardiograms (Tomtec research arena). The aim of the study was to compare these new methods with standard methods. Methods Patients undergoing clinical MPS were invited to an echocardiographic examination. Eighty-eight patients were included, mean age 64 ± 10 years, 50% men. LV volumes and LVEF from the echocardiographic examinations were calculated using the AutoEF software and calculations according to Simpson's rule. The LV volumes and LVEF from the MPS images were calculated using CAFU, Quantitative gated-SPECT (QGS) and Emory Cardiac Toolbox (ECT). Results The MPS methods revealed larger LV volumes and LVEF compared with the echocardiographic methods. CAFU showed an excellent correlation with QGS and ECT (0.91–0.99). The correlations between the MPS and the echocardiographic methods (0.47–0.88), as well as between the AutoEF-assessed values and Simpson's method (0.57–0.87), were lower, however statistically significant. The correlations between the methods were higher for LV volumes than for LVEF. Conclusion There was better agreement between LV volumes and LVEF values from the three MPS methods than between those from the two echocardiographic methods. The echocardiographic methods produced significantly lower LV volumes and LVEF compared with the MPS methods. In the clinical situation, LV volumes and LVEF values from different types of examination or different software packages should be treated with caution.

Normal limits for left ventricular ejection fraction and volumes determined by gated single photon emission computed tomography – a comparison between two quantification methods

To compare gender-related normal limits for left ventricular (LV) ejection fraction (EF), end-diastolic and end-systolic volumes (EDV and ESV), obtained using two myocardial perfusion-gated single photon emission computed tomography (SPECT) quantification methods. A total of 185 patients were retrospectively selected from a consecutive series of patients examined for coronary artery disease (CAD) or for management of known CAD. Patients were included in the study group if they had normal or probably normal results with stress and rest perfusion imaging and if the combined interpretation of perfusion studies and gated rest studies showed no signs or suspicion of myocardial infarction. The gated SPECT studies were performed using a 2-day stress/gated rest Tc-99m sestamibi protocol. All patient studies were processed using CAFU and quantitative-gated SPECT (QGS), the two software packages for quantification of gated SPECT images. The lower normal limits for EF were higher for CAFU compared with QGS for both women (59% versus 53%) and men (54% versus 47%). The upper normal limits for EDV were also higher for CAFU compared with QGS for both women (133 versus 107 ml) and men (182 versus 161 ml). The differences between the software packages were small for ESV (women 44 versus 44 ml; men 69 versus 74 ml). Gender-specific normal limits need to be applied for LV EF and volumes determined by gated SPECT. Separate criteria for abnormal LV EF and EDV need to be used for women and men depending on the software package used.

Prediction of Remote Left Ventricular Volumes and Functions After Acute Myocardial Infarction With Successful Coronary Intervention

The scintigraphic perfusion defect size (DS) at 1 week after acute myocardial infarction (AMI) predicts remote left ventricular (LV) volumes and LV ejection fraction (LVEF). The present study examined whether LV volumes and LVEF 6 months after AMI may be better predicted by the combination of LV volumes and LVEF just after reperfusion, and DS at 1 week, after AMI in patients with Thrombolysis In Myocardial Infarction (TIMI) grade III reperfusion by percutaneous coronary intervention. In 48 patients with AMI and TIMI grade III reperfusion, quantitative gated SPECT (QGS) was performed just after reperfusion, and at 1 week and 6 months after AMI. LV end-diastolic volume index decreased (108+/-8 to 93+/-6 ml/m(2), p<0.05) and LVEF increased (44+/-3 to 50+/-2%, p<0.05) 6 months after AMI. In addition, they were better predicted by a combination of LV volumes and LVEF just after reperfusion and DS at 1 week after AMI. In AMI with TIMI grade III reperfusion, LV volumes and LVEF at 6 months after MI correlate with the values obtained just after reperfusion. Myocardial perfusion imaging combined with QGS at reperfusion may predict these late-phase parameters.

心電図同期心筋血流ＳＰＥＣＴによるｃｅｎｔｅｒｌｉｎｅ法を用いた壁運動定量評価

Evaluation of myocardial wall motion is an important assessment of heart function. Specific analysis programs in nuclear medicine, such as QGS (quantitative gated SPECT) analysis and p-FAST (perfusion-function assessment for myocardial SPECT), have been used to assess wall motion, but they have not evaluated it through a comparison of normal data. The centerline method, using left ventriculograms (LVG), evaluates regional wall motion quantitatively through a comparison of normal data and patient data, and abnormality of wall motion is expressed in units of standard deviation (SD) s from the mean motion in a reference population. However, angiography is an invasive inspection, wall motion analysis is usually in one direction, and the conventional centerline method is not a three-dimensional analysis. The purpose of this study was to apply the centerline method to nuclear medicine and examine the wall motion of subjects through a comparison of normal wall motion non-invasively and in a three-dimensional way. We arranged the analysis program using C language and inspected it using a dynamic cardiac phantom and computed tomography (CT) scanner. We made a polar map that indicated the mean and SD of normal wall motion. Our proposed method was able to assess the wall motion of subjects quantitatively through a comparison of normal wall motion in nuclear medicine.

Noninvasive Assessment of Left Ventricular Function Prior to and 6 Months After Renal Transplantation

Background The purpose of this study was to evaluate the effect of a successful kidney transplantation on left ventricular functional parameters that can be measured with gated–single photon emission computed tomography (gated-SPECT) myocardial perfusion scintigraphy in patients with end-stage renal disease. Materials and Methods Thirty-two consecutive patients (22 male) who had undergone a successful kidney transplantation in whom gated-SPECT myocardial perfusion scintigraphy was performed prior to and 6 months after surgery were included. Functional parameters, such as left ventricular ejection fraction (LVEF), wall motion, and wall thickening, were calculated with quantitative gated-SPECT. Results The mean LVEF improved significantly ( P < .001) from 52% (SD ± 11) before to 63% (SD ± 10) after renal transplantation. This was attributable to a significant improvement in the end-systolic volume ( P = .028). Wall motion and wall thickening improved in almost all myocardial segments. We found a significant correlation between the levels of urea and creatinine and the LVEF. However, correlations between an increase in the LVEF and the improvement in urea ( P = .30) and creatinine ( P = .26) levels were not significant, which is probably related to the number of patients studied. Conclusion The systolic left ventricular dysfunction in terms of LVEF, wall motion, and wall thickening improves significantly 6 months after kidney transplantation in patients with end-stage kidney disease. Long-term follow-up is required to establish the prognostic value of these findings.

SU‐FF‐I‐108: Estimation of Ejection Fractions by Three Quantitative Gated SPECT Software Packages

Purpose: To investigate the accuracy of left ventricular ejection fraction (LVEF) estimated from three quantitative gated SPECT software packages, using echocardiography as a gold standard and the reliability of LVEF from ordered subset expectation maximization (OS‐EM). Method and Materials: Seventy patients with suspected coronary artery disease (CAD) were examined with gated 99mTc‐MIBI SPECT (8 frames/cardiac cycle) at stress. The projection datasets were reconstructed using OS‐EM with 8 angles/subset. The data were smoothed with Gaussian filter with FWHM of 8 pixel width. The iteration numbers were varied for each software: 3 iterations for quantitative gated SPECT (QGS), 5 iterations for the Emory cardiac toolbox (ECTb), and 4 iterations for 4D‐MSPECT. The LVEFs were calculated using these 3 quantitative software packages. To test reliability of LVEF from OS‐EM, the same patient data were again reconstructed using filtered backprojection (FBP) with post‐filtering of Butterworth 5th order, 0.3 cycles/pixel cutoff frequency. A two tailed pair t‐test was used to test the statistically significant difference with p‐value &lt; 0.05. Results: There were no statistically significant differences in LVEFs for all three software packages from echocardiography with p &gt; 0.05. The correlation between LVEF in each pair of package was high (r &gt; 0.9). The LVEFs from OS‐EM were not statistically significantly different from that from FBP (p &gt; 0.05) for QGS and 4D‐MSPECT, but for ECTb, there was a statistically significant difference. The LVEF from OS‐EM correlated well with that from FBP (r &gt;0.9). Conclusion: The LVEF estimated from each software package had different characteristics and the LVEF from OS‐EM was reliable.

Gated Myocardial Perfusion SPECT in Patients With a Small Heart: Effect of Zooming and Filtering

Abstract: Underestimation of left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and overestimation of ejection fraction (LVEF) in patients with a small heart is a problem with the gated myocardial perfusion SPECT (GSPECT). Thirty patients with a small heart underwent rest Tc-99m sestamibi GSPECT using acquisition zooms of 1.45 and 1.78 consecutively. After reconstruction by filtered back-projection using different cut-off frequencies of Butterworth filter, LVEF, EDV and ESV were computed using a quantitative gated SPECT (QGS) program. Increasing in zooming or filter cut-off frequency resulted in higher EDV and ESV but lower LVEF. Differences in LVEF between 2 acquisition zooms were decreased by sharper cut-off frequencies. A higher zooming and/or a sharper filter might be suggested for quantitative GSPECT in patients with a small heart.

Diferenças relacionadas ao sexo nos volumes ventriculares e na fração de ejeção do ventrículo esquerdo estimados por cintilografia de perfusão miocárdica: comparação entre os programas Quantitative Gated SPECT (QGS) e Segami

To test for gender differences in the measurements obtained by Segami and Quantitative Gated SPECT (QGS) software programs. 181 asymptomatic individuals without heart disease were submitted to myocardial perfusion imaging. End-diastolic volumes (EDV), end-systolic volumes (ESV) and left ventricular ejection fraction (LVEF) were measured by QGS and Segami software programs to evaluate the influence of gender, age, weight, height, heart rate, systolic blood pressure, diastolic blood pressure, body mass index and body surface area. The means in the QGS method were: EDV (women= 68 ml; men= 95 ml; p<0.001), LVEF (women= 66.24%; men= 58, 7%) and Segami: EDV (women= 137 ml; men= 174 ml), LVEF (women= 62.67%; men= 58, 52%). There were significant differences between men and women in the EDV (p<0.001), ESV (p<0.001) and LVEF (p=0.001) that persisted after adjusting for body surface area. Ventricular volumes were significantly lower and LVEF was significantly higher in women, estimated by QGS or Segami software programs.

Gated SPECT Findings Revealing Diastolic Dysfunction in Acute Hypothyroidism

The purpose of this study was to assess left ventricular (LV) function by gated SPECT in acute hypothyroidism. Thirty-eight acute hypothyroid patients without any cardiac disease and 40 healthy controls underwent gated SPECT at rest. Fourteen patients had a second examination during thyroxine replacement therapy. Gated SPECT was performed using Tc-99m sestamibi with 16 frames per cardiac cycle. The LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), peak ejection rate (PER), peak filling rate (PFR), and time to peak filling (TTPF) were measured by quantitative gated SPECT (QGS). Systolic wall thickening/motion was determined in 5 myocardial segments. Hypothyroid patients exhibited a decrease in PFR (222 +/- 52 EDV/s) and prolongation of TTPF (194 +/- 32 msec) as compared with controls (247 +/- 41 EDV/s and 179 +/- 17 msec, respectively; P < 0.05). During thyroxine therapy, the mean values for EDV (74 +/- 21 mL) and PFR (265 +/- 64 EDV/s) increased significantly in 14 follow-up patients (pretreatment values 67 +/- 18 mL and 219 +/- 50 EDV/s, respectively; P < 0.05). A significant difference was detected in the mean TTPF between the thyroxine group and the controls (195 +/- 35 msec vs 179 +/- 17 msec; P < 0.05). No significant differences were found in wall thickening and motion values (P > 0.05). Gated SPECT findings revealed diastolic dysfunction as indicated by a decrease in PFR and a prolongation in TTPF in patients with acute hypothyroidism.

Normal limits of ejection fraction and volumes determined by gated SPECT in clinically normal patients without cardiac events: a study based on the J-ACCESS database

Quantitative gated single-photon emission computed tomography (SPECT) is known to have high accuracy and precision for measurement of the principal cardiac functional parameters. We hypothesised that normal values for EF and LV volumes may differ among nationalities, and that optimal threshold values specific to the study population are required. Among 4,670 consecutively registered patients for a J-ACCESS (Japanese investigation regarding prognosis based on gated SPECT) study from 117 hospitals, a total of 268 (149 women, 119 men) were selected who had no baseline cardiac diseases and had experienced no cardiac events during the preceding 3-year period. A gated SPECT study was performed with 99mTc-tetrofosmin and analysed with Cedars Sinai Medical Center's quantitative gated SPECT (QGS) software. The results in respect of ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV), and EDV, ESV and SV normalised by body surface area (EDVI, ESVI and SVI), were calculated and summarised to obtain normal limits. EF for women and men was 74 +/- 9% and 63 +/- 7%, respectively (p < 0.0001). EDV, ESV and SV were significantly smaller in women than in men. Based on multiple regressions for linear models, the primary and secondary predictors of EF, EDVI, ESVI were gender and age. By stepwise multiple regression analysis, a statistically significant third predictor for EDV, ESV, SV and SVI was body weight. No colinearity was found between age and body weight. Important factors for the studied Japanese population included a high incidence of small hearts in women and the relatively advanced age of the population (the mean age +/-SD was 64.1 +/- 10.0 years for women and 60.9 +/- 11.7 years for men). EF and volumes determined by gated SPECT with QGS were significantly affected by gender and age, with body weight as a third predictor for volumes. Moreover, the normal limits were so specific for the population studied that standards appropriate for the study in question should be utilised.

Accurate estimation of regional and global cardiac function in old myocardial infarction patients by multidetector-row computed tomography

Recently we can evaluate cardiac function by multidetector-row computed tomography (MDCT) and quantitative gated SPECT(QGS) as well as left ventriculography (LVG). We evaluated regional and global cardiac function using MDCT and QGS, compared to LVG, and also evaluated parameters of left ventricular (LV) diastolic function using MDCT. Regional cardiac function was evaluated using shortening fraction(SF). Global cardiac function was evaluated using ejection fraction(EF). The peak filling rate(PFR) and the ratio of time to peak filling rate to RR interval(tPFR/RR) on MDCT were measured as parameters of LV diastolic function. The SFs by MDCT and LVG were correlated in almost each segment, but those by QGS and LVG were not correlated in some each segment. The SFs by QGS and LVG were not correlated in the myocardial infarcted segments, but those by QGS and LVG were correlated in the non-infarcted segments. Except for patients who had wall motion abnormalities at the ventricular septum or posterolateral wall, the EFs by MDCT and LVG were correlated, but those by QGS and LVG were not correlated. MDCT was more useful in detecting regional and global cardiac function compared to QGS, and parameters of LV diastolic function could be also measured by MDCT.

Evaluation of right and left ventricular function by quantitative blood-pool SPECT (QBS): Comparison with conventional methods and quantitative gated SPECT (QGS)

Though quantitative ECG-gated blood-pool SPECT (QBS) has become a popular tool in research settings, more verification is necessary for its utilization in clinical medicine. To evaluate the reliability of the measurements of left and right ventricular functions with QBS, we performed QBS, as well as first-pass pool (FPP) and ECG-gated blood-pool (GBP) studies on planar images in 41 patients and 8 healthy volunteers. Quantitative ECG-gated myocardial perfusion SPECT (QGS) was also performed in 30 of 49 subjects. First, we assessed the reproducibility of the measurements of left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume (LVEDV, RVEDV) with QBS. Second, LVEF and RVEF obtained from QBS were compared with those from FPP and GBP, respectively. Third, LVEF and LVEDV obtained from QBS were compared with those from QGS, respectively. The intra- and inter-observer reproducibilities were excellent for LVEF, LVEDV, RVEF and RVEDV measured with QBS (r = 0.88 to 0.96, p < 0.01), while the biases in the measurements of RVEF and RVEDV were relatively large. LVEF obtained from QBS correlated significantly with those from FPP and GBP, while RVEF from QBS did not. LVEF and LVEDV obtained from QBS were significantly correlated with those from QGS, but the regression lines were not close to the lines of identity. In conclusion, the measurements of LVEF and LVEDV with QBS have good reproducibility and are useful clinically, while those of RVEF and RVEDV are less useful compared with LVEF and LVEDV. The algorithm of QBS for the measurements of RVEF and RVEDV remains to be improved.

Development of quantification software using model-based segmentation of left ventricular myocardium in gated myocardial SPECT

Gated myocardial single photon emission computed tomography (SPECT) is being used for the diagnosis of coronary artery diseases. In this study, we developed new software for the quantification of volumes and ejection fraction (EF) on the gated myocardial SPECT data using a cylindrical model. Volumes and EF by developed software were validated by comparing with those quantified by quantitative gated SPECT (QGS) software. Cylinder model for left ventricular myocardium was used to eliminate background activity and count profiles across the myocardium were fitted to the Gaussian curve to determine the endocardial and epicardial boundary. End-diastolic volume (EDV), end-systolic volume (ESV) and EF were calculated using this boundary information. Gated myocardial SPECT was performed in 83 patients. EDV, ESV and EF values estimated using present method were compared to those obtained using the commercialized software QGS, and reproducibility in the parameter estimation was assessed. EF, EDV and ESV obtained using two methods were correlated well (correlation coefficients = 0.96, 0.96 and 0.98). The correlation between the parameters repetitively estimated from the same data set by an operator was very high (correlation coefficients = 0.96, 0.99 and 0.99 for EF, EDV and ESV). On the repeated acquisition, reproducibility was also high with correlation coefficients of 0.89, 0.97 and 0.98. The present software will be useful for the development of new parameters for describing the perfusion and function of the LV.

Validation of a new automated method for analysis of gated‐SPECT images

We recently presented a new method for quantification of CArdiac FUnction--denoted CAFU--as the first step in the development of an automated method for integrated interpretation of gated myocardial perfusion single photon emission computed tomography (SPECT) images. The aim of this study was to validate CAFU in the assessment of global and regional function of the left ventricle. Quantitative gated-SPECT (QGS), the most widely used software package for quantification of gated-SPECT images, was used as reference method for the measurements of ejection fraction (EF) and ventricular volumes, and visual analysis by an experienced physician was used as reference method for the measurements of regional wall motion and thickening. Two different groups of consecutive patients referred for myocardial perfusion scintigraphy were studied. Global function was evaluated in 316 patients and regional function in 49 other patients. The studies were performed using a 2-day stress/rest 99 m-Tc-sestamibi protocol. A good correlation was found between EF values from QGS and CAFU (EF CAFU = 0.84 EF QGS + 13, r = 0.94), but CAFU values were on average 4 EF points higher than QGS values. With CAFU the segments with normal thickening according to the physician showed significantly higher thickening values (in all parts of the myocardium) compared to the segments classified as having abnormal thickening. In conclusion, this study demonstrates that CAFU can be used to quantify global and regional function in gated-SPECT images. This is an important step in our development of an automated method for integrated interpretation of gated-SPECT myocardial perfusion scintigraphy studies.

Evaluation of left ventricular ejection fraction by the quantitative algorithms QGS, ECTb, LMC and LVGTF using gated myocardial perfusion SPECT: investigation of relative accuracy

To compare the quantitative algorithms Emory Cardiac Toolbox (ECTb), quantitative gated SPECT (QGS), layer of maximum counts (LMC), and left ventricular global thickening fraction (LVGTF) using gated myocardial tomography in the calculation of the left ventricular ejection fraction using the regression without truth (RWT) technique. Seventy-four consecutive patients were included in the study (59 males). All patients underwent stress-rest myocardial perfusion SPECT using Tc-tetrofosmin. Analysis of variance (ANOVA), the paired Student's t-test, the Pearson correlation coefficient and Bland-Altman were used for comparing the methods. The relative accuracy was performed by RWT. ANOVA revealed a significant difference among the methods in calculating the ejection fraction. RWT showed that ECTb and QGS outperformed the other two methods. The ECTb was slightly better than QGS, and LMC was slightly better than LVGTF. QGS and ECTb achieved good correlations in end diastolic volume, end systolic volume and ejection fraction measurements. One-way ANOVA demonstrated that QGS was the only software program affected by the category of the perfusion summed stress score (SSS), P=0.038. The ejection fraction determined by the QGS, ECTb and LVGTF methods correlated significantly with defect size (r=0.545, P<0.0001; r=0.530, P<0.0001; and r=0.419, P<0.0001, respectively), but the LMC method was not significantly correlated (r=0.216, P=0.067). There was a considerable variation among the quantitative gated SPECT methods in the evaluation of the ejection fraction. RWT revealed that the ECTb and QGS outperformed the other two methods with respect to the bias and precision of the measurements. Pair-wise correlations of the four methods ranged from mild to good with large agreement limits. Results of RWT provided important information in ranking the quantitative gated SPECT methods.