Reproducibility of left ventricular volume and ejection fraction measurements in rat using pinhole gated SPECT

Purpose The aim of this study was to investigate the intra-individual reproducibility of left ventricular volume and ejection fraction measurements in living rat using pinhole gated single-photon emission computed tomography (SPECT).Methods Eight normal male Wistar rats underwent four pinhole gated SPECT acquisitions over a 1-month period. Two pinhole gated myocardial perfusion SPECT studies were acquired at a 1-week interval after injecting the animals with 439±52 MBq of ^99mTc-sestamibi. Subsequently, 1 week after the perfusion studies, two pinhole gated blood pool SPECT studies were acquired at a 1-week interval after in vivo labelling of the red blood cells using 520±49 MBq of ^99mTc-pertechnetate. Pinhole gated SPECT acquisitions were done on a single-head gamma camera equipped with a pinhole collimator with a 3-mm opening and 165-mm focal length. Parameters of acquisition were as follows: 44 mm radius of rotation, 360° rotation using a circular orbit, 64 projections, 64×64 matrix, gating using 16 time frames and 22-min acquisition time. The projection data were reconstructed with a modified version of OSEM taking into account the pinhole geometry and incorporating a prior assumption about the temporal properties of gated SPECT studies to reduce noise. Left ventricular volumes and ejection fraction were measured using automatic quantification algorithms. Inter-study, inter-observer and intra-observer reproducibility was investigated.Results Pinhole gated myocardial perfusion and pinhole gated blood pool images were of high quality in all animals. No significant differences were observed between the repeated measurements. The pinhole gated myocardial perfusion SPECT studies indicated that differences between repeated measurements larger than 41 l for end-diastolic volume, 17 l for end-systolic volume and 3% for ejection fraction were significant. The pinhole gated blood pool SPECT studies indicated that differences between repeated measurements larger than 42 l for end-diastolic volume, 38 l for end-systolic volume and 5% for ejection fraction were significant. In addition to the reproducibility measures, the accuracy of volume measurements in pinhole gated blood pool SPECT was confirmed by a phantom study. Excellent correlations were observed between the measured volumes and the actual phantom volumes.Conclusion Pinhole gated SPECT is an accurate and reproducible technique for cardiac studies of small animals. Because this technique is non-invasive, the same animal can be imaged repetitively, allowing follow-up studies.     

Factors affecting left ventricular ejection fraction using automated quantitative gated SPECT

BACKGROUND: Factors affecting the accuracy of left ventricular ejection fraction (LVEF) quantification using automated quantitative gated SPECT have not been adequately investigated in patients in the clinical setting. Therefore, the authors studied the effect of defect size and Tc-99m tetrofosmin dose on the accuracy of LVEF calculation using the automated QGS program. MATERIALS AND METHODS: Thirty-two consecutive patients underwent gated rest and stress myocardial perfusion SPECT after administration of 8 and 27 mCi Tc-99m tetrofosmin, respectively. The LVEF was obtained for both the rest and stress studies using the QGS program and compared with the LVEF obtained using quantitative echocardiography performed within 2 weeks. Myocardial perfusion defects were recorded as scarring, ischemia, or mixed scarring and ischemia in 12 left ventricular segments. The defect size was evaluated by adding the number of affected segments. RESULTS: The mean LVEF calculated using high-dose stress QGS, low-dose rest QGS, and echocardiography was 49.2% +/- 15%, 46.2% +/- 17% and 48.7% +/- 16.9% respectively, with no statistically significant differences. The LVEF obtained using high-dose stress QGS correlated better with echocardiography than did that obtained using low-dose rest QGS (r = 0.86 versus 0.76). In addition, when the high-dose stress LVEF in the 14 patients with normal myocardial perfusion was compared with that in 11 patients who had one- or two-segment perfusion defects, and 7 patients who had perfusion defects in > or = three segments, there was good correlation with echocardiography in the three patient groups (r = 0.85, 0.88, and 0.91, respectively). CONCLUSIONS: Myocardial perfusion defects do not affect the accuracy of LVEF calculation using automated QGS. High-dose gated myocardial SPECT demonstrated better correlation with quantitative echocardiography LVEF results.     

Variability of serial same-day left ventricular ejection fraction using quantitative gated spect

BACKGROUND: The accuracy of quantitative gated single photon emission computed tomography (SPECT) (QGS) and the potential limitations for estimation of left ventricular ejection fraction (LVEF) have been extensively evaluated. However, few studies have focused on the serial variability of QGS. This study was conducted to assess the serial variability of QGS for determination of LVEF between 2 sequential technetium 99m sestamibi-gated SPECT acquisitions at rest in both healthy and unhealthy subjects. METHODS AND RESULTS: The study population consisted of 2 groups: group I included 21 volunteers with a low likelihood of CAD, and group II included 22 consecutive patients with documented CAD. Both groups underwent serial SPECT imaging. The overall correlation between sequential images was high (r = 0.94, SEE = 5.3%), and the mean serial variability of LVEF was 5.15% +/- 3.51%. Serial variability was lower for images with high counts (3.45% +/- 3.23%) than for images with low counts (6.85% +/- 3.77%). The mean serial variability was not different between normal and abnormal high-dose images (3.0% +/- 1.56% vs 3.9% +/- 2.77%). However, mean serial variability for images derived from abnormal low-dose images was significantly greater than that derived from normal low-dose images (9.6% +/- 2.22% vs 3.1% +/- 2.12%, P <.05). CONCLUSIONS: Although QGS is an efficacious method to approximate LVEF values and is extremely valuable for incremental risk stratification of patients with coronary artery disease, it has significant variability in the estimation of LVEF on serial images. This should be taken into account when used for serial evaluation of LVEF.     

Attenuation corrected gated SPECT for the assessment of left ventricular ejection fraction and volumes

OBJECTIVE: The aim of this study was to evaluate the value of attenuation correction (AC) of Tc-99m tetrofosmin single-photon emission tomography (SPECT) imaging for the assessment of left ventricular ejection fraction (LVEF). METHODS: Attenuation corrected and non-attenuation corrected (NC) resting Tc-99m tetrofosmin SPECT were compared for the assessment of LVEF. Planar multigated radionuclide angiography (MUGA) served as the reference for LVEF assessment. Patients (n = 56) with left ventricular dysfunction who underwent MUGA and rest gated Tc-99m tetrofosmin SPECT within 1 month were included. RESULTS: The average LVEF on NC gated SPECT was 37.4 +/- 11.8% and on AC SPECT 38.5 +/- 13.4% (P = NS). The absolute mean difference of the LVEF between the MUGA and NC gated SPECT and AC gated SPECT was -0.2% (95% CI -1.7 to 1.3) and -1.3% (95% CI -2.7 to 0.03), respectively (P = NS both vs. MUGA). The correlation between NC gated SPECT and AC gated SPECT versus MUGA measurement was high with a correlation coefficient of 0.89 (P < 0.01) and 0.92 (P < 0.01), respectively. End-diastolic volumes (EDVs) and end-systolic volumes (ESVs) were significantly higher with AC gated SPECT when compared with NC gated SPECT (both P < 0.001). CONCLUSIONS: Profile AC gated Tc-99m tetrofosmin SPECT agrees well with MUGA and NC gated Tc-99m tetrofosmin SPECT for the assessment of LVEF. EDVs and ESVs are significantly higher with AC gated SPECT when compared with NC gated SPECT.     

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.     

Differences in left ventricular ejection fraction and volumes measured at rest and poststress by gated sestamibi SPECT

Background  Some studies suggested that the poststress left ventricle ejection fraction (LV EF) is lower than rest LV EF in patients with stress-induced ischemia. Methods and Results  By using a 2-day protocol and 30 mCi Tc-99m sestamibi, LV EF, end-systolic volume (ESV), and end-diastolic volume (EDV) were measured with gated SPECT. Of 99 eligible patients, 91 had technically adequate studies. Poststress LV EF minus rest LV EF was defined as ΔLV EF. ΔEDV and ΔESV were similarly defined. Rest and poststress LV EF (r = 0.89), EDV (r = 0.78), and ESV (r = 0.93) were highly correlated (P <.001). Rest LV EF, EDV, and ESV were not significantly different between patients with and without stress-induced ischemia. ΔLV EF was significantly lower in patients with stress-induced ischemia (-3.5% ± 4.5% vs -1.1% ± 4.7%, P ± .02). Mean LV EF poststress in ischemic patients was 55.0% ± 10.5% vs 61.2% ± 10.0% in nonischemic patients (P = .008). However, only 1 patient (3%) with ischemia had ΔLV EF that exceeded the 95% confidence limit of ΔLV EF for normal patients. Ischemia was significantly associated with increased ΔEDV and ΔESV (P <.01). Conclusions  Stress-induced ischemia is associated with poststress reduction in LV EF and increased poststress EDV and ESV. However, the effect of ischemia on the difference between poststress and rest EF measurements is modest and rarely exceeds the confidence limits in normal patients undergoing 2-day protocols. In most patients, poststress LV EF is an accurate reflection of rest LV EF.     

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.     

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.     

Variability of left ventricular ejection fraction and volumes with quantitative gated SPECT: influence of algorithm,pixel size and reconstruction parameters in small and normal-sized hearts

Purpose Several software packages are commercially available for quantification of left ventricular ejection fraction (LVEF) and volumes from myocardial gated single-photon emission computed tomography (SPECT), all of which display a high reproducibility. However, their accuracy has been questioned in patients with a small heart. This study aimed to evaluate the performances of different software and the influence of modifications in acquisition or reconstruction parameters on LVEF and volume measurements, depending on the heart size.Methods In 31 patients referred for gated SPECT, 64² and 128² matrix acquisitions were consecutively obtained. After reconstruction by filtered back-projection (Butterworth, 0.4, 0.5 or 0.6 cycles/cm cut-off, order 6), LVEF and volumes were computed with different software [three versions of Quantitative Gated SPECT (QGS), the Emory Cardiac Toolbox (ECT) and the Stanford University (SU-Segami) Medical School algorithm] and processing workstations. Depending upon their end-systolic volume (ESV), patients were classified into two groups: group I (ESV>30 ml, n=14) and group II (ESV<30 ml, n=17). Agreement between the different software packages and the influence of matrix size and sharpness of the filter on LVEF and volumes were evaluated in both groups.Results In group I, the correlation coefficients between the different methods ranged from 0.82 to 0.94 except for SU-Segami (r=0.77), and were slightly lower for volumes than for LVEF. Mean differences between the methods were not significant, except for ECT, with which LVEF values were systematically higher by more than 10%. Changes in matrix size had no significant influence on LVEF or volumes. On the other hand, a sharper filter was associated with significantly larger volume values though this did not usually result in significant changes in LVEF. In group II, many patients had an LVEF in the higher range. The correlation coefficients between the different methods ranged between 0.80 and 0.96 except for SU-Segami (r=0.49), and were slightly worse for volumes than for LVEF values. In contrast to group I, however, inter-method variability was quite large and most mean LVEF differences were significant. LVEF was systematically highest with ECT and lowest with SU-Segami. With QGS, changes in matrix size from 64² to 128² were associated with significantly larger volumes as well as lower LVEF values. Increasing the filter cut-off frequency had the same effect. With SU-Segami, a larger matrix was associated with larger end-diastolic volumes and smaller ESVs, resulting in a highly significant increase in LVEF. Increasing the filter sharpness, on the other hand, had no influence on LVEF though the measured volumes were significantly larger. Conclusion In patients with a normal-sized heart, LVEF and volume estimates computed from different commercially available software packages for quantitative gated SPECT are well correlated. LVEF and volumes are only slightly sensitive to changes in matrix size. Smoothing, by contrast, is associated with significant changes in volumes but usually not in LVEF values. However, owing to the specific characteristics of each algorithm, software should not be interchanged for follow-up in an individual patient. In small hearts, on the other hand, both the used software and the matrix size or smoothing significantly influence the results of quantitative gated SPECT. LVEF values in the higher range are frequently observed with all the studied software except for SU-Segami. A larger matrix or a sharper filter could be suggested to enhance the accuracy of most commercial software, more particularly in patients with a small heart.     

Clinical application of left ventricular volume and ejection fraction derived from gated SPECT data

Left ventricular (LV) volume and ejection fraction (LVEF) derived from ECG-gated myocardial SPECT data are reproducible and objective. Those quantitative values, however, interacted according to varied factors such as a frame number per R-R interval, tracers, and processing-algorisms. A decrease of frame number per R-R interval yields underestimation of end-diastolic volume and overestimation of end-systolic volume, resulting in underestimation of LVEF. Thus, it is important to change a frame number per R-R interval by the examination purpose. A good correlation of LVEF is usually obtained, independent of a combination of tracer and processing-algorism. On the other hand, LV volume does not always show linearity between combinations of tracer and processing-algorism. An extraction of myocardial edge using QGS program is deteriorating in patients with small LV below 20 ml. It is crucial to assess LV functional values derived from ECG-gated SPECT data as clinical indices, taking the varied effects into consideration.     

Impact of Wiener filter in determining the left ventricular volume and ejection fraction using thallium-201 gated SPECT

Patient morphology, as well as the acquisition and reconstruction parameters, may influence the evaluation of the left ventricular volume (LVV) and left ventricular ejection fraction (LVEF) using gated single-photon emission computed tomography (SPECT). The purpose of this study was to examine the influence of gender and reconstruction filter on the measurement of LVV and LVEF using 201Tl gated SPECT. Using a static torso phantom, a female shape was created by the addition of two saline solution-filled balloons fixed on the anterior rib cage. The following parameters were similar for all acquisitions: 90 degrees dual-head gamma camera; 32 projections; 64x64 matrix (pixel size=6.77x6.77 mm); two 20% energy windows centred at 70 and 167 keV. The following acquisition times were tested: 1.25, 10, 20, 30 and 40 s per projection, leading to a total of 10 successive acquisitions. The effect of over-sampling was tested by 2.5 post-acquisition zooming. All SPECT images were successively reconstructed using filtered back-projection with Butterworth and Wiener filters. The effect of gender and reconstruction filter was also studied in 30 patients (15 males and 15 females) with a low likelihood of coronary artery disease. LVVs were calculated using QGS software. By multivariate analysis, the following factors influenced the accuracy of phantom measurement using QGS software: zooming (F=49, P<0.0001), phantom shape (F=61, P<0.0001) and filter type (F=240, P<0.0001). LVV was underestimated in the female shape phantom, even when using the Wiener filter. In patients, LVV and LVEF measurements were independently influenced by gender (P<0.0001) and filter (P<0.0001), but not by zooming. In conclusion, it was demonstrated that LVV was significantly decreased in the female shape phantom, suggesting a significant impact of breast interposition. This underestimation was minimized by use of the Wiener filter. In patients, the impact of the Wiener filter on the assessment of LVVs and LVEF was powerful, but independent of gender, and failed to correct the underestimation of LVVs and the overestimation of LVEF in females.     

Non-invasive detection of ischemic left ventricular dysfunction using rest gated SPECT: expectation of simultaneous evaluation of both myocardial perfusion and wall motion abnormality

OBJECTIVE: Although the accurate detection of ischemic etiology is important in the management of patients with severe left ventricular (LV) dysfunction, it is difficult to determine using a non-invasive strategy. The present study investigates whether perfusion and regional functional abnormalities identified by quantitative electrocardiographic gated single-photon emission computed tomography (QGS) at rest can detect ischemic LV dysfunction in patients with severe LV dysfunction. METHODS: Rest QGS with (99m)Tc-tetrofosmin was performed on 54 consecutive patients with LV ejection fraction of 相似文献   

Performance of a fully automated program for measurement of left ventricular ejection fraction

A fully automated program developed by us for measurement of left ventricular ejection fraction from equilibrium gated blood pool studies was evaluated in 130 additional patients. Both 6-min (130 studies) and 2-min (142 studies in 31 patients) gated blood pool studies were acquired and processed. The program successfully generated ejection fractions in 86% of the studies. These automatically generated ejection fractions were compared with ejection fractions derived from manually drawn regions of interest. When studies were acquired for 6-min with the patient at rest, the correlation between automated and manual ejection fractions was 0.92. When studies were acquired for 2-min, both at rest and during bicycle exercise, the correlation was 0.81. In 25 studies from patients who also underwent contrast ventriculography, the program suceessfully generated regions of interest in 22 (88%). The correlation between the ejection fraction determined by contrast ventribulography and the automatically generated radionuclide ejection fraction was 0.79.This work was supported in part by USPHS Grant GM 10548     

Quantitative gated blood pool SPECT for the assessment of coronary artery disease at rest

Background  Planar gated blood pool imaging (GBPI) has long proven to be useful for the noninvasive assessment of ventricular function. From a practical viewpoint, gated blood pool single photon emission computed tomography (GBPS) acquisition can be accomplished in the same time as a three-view planar series, with the benefit of a tomographic perspective that avoids chamber overlap. Methods and Results  Quantitative gated blood pool SPECT was applied to 10 patients who underwent coronary arteriography, contrast ventriculography, and planar gated blood pool imaging. For each patient, the mid-short axis oblique slice was divided into 4 discrete segments using 4 different reference models and 2 forms of segmentation. A center of mass (counts) fixed in the end-diastolic frame and segmentation that bisected the ventricular septum proved to have the highest sensitivity and specificity for determining regional wall motionormalities at rest in myocardium supplied by severely diseased coronary arteries (>75%). GBPS correctly identified 19 of 21 abnormal segments (90%), with good specificity (95%), whereas ventriculography identified 12 (57%) and planar GBPI identified 9 (43%) of the segments supplied by diseased coronaries. Conclusion  Quantitative GBPS appears to be a sensitive method for assessing coronary artery disease at rest in myocardium perfused by severely diseased coronary arteries. Presented in part at the 43th Annual Meeting of the Society of Nuclear Medicine, Denver, Colo, 1996.     

Comparison of automatic quantification software for the measurement of ventricular volume and ejection fraction in gated myocardial perfusion SPECT

The aim of this study was to compare the performance of three different software packages for the calculation of ejection fraction (EF) and end diastolic volume (EDV) from gated myocardial single photon emission computed tomography studies. Two hundred patients undergoing gated stress myocardial perfusion scans were analysed retrospectively. Patients were grouped as follows: small heart (n=31), normal perfusion scan (n=71), and scan with perfusion defects (n=98). EF and EDV were calculated for each using QGS (Cedars Sinai, Los Angeles, CA), 4D-MSPECT (University of Michigan, Ann Arbor, MI), and ECT (Emory University, Atlanta, GA). Bland-Altman plots, repeated measures ANOVA, and linear regression analysis were used to compare methods. Correlation coefficients between the methods for both EF and EDV were high, greater than 0.9. However, Bland-Altman plots revealed a large standard deviation of the difference between methods, preventing the confident estimate of the value of one method from an observation of another. Despite good correlation, the variance between methods was high. These algorithms behave differently, produce widely variable results from one another, and should not be used interchangeably. It may prove prudent for laboratories to independently validate the software algorithm that is chosen against a 'gold standard' using their own population.     

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.     

Effect of reversible hypoperfusion on left ventricular volumes measured with gated SPECT at rest and after adenosine infusion

BACKGROUND: The aims of this study were to assess the degree of postischemic left ventricular (LV) dilatation after adenosine stress and to determine the extent to which LV volumes measured with gated single photon emission computed tomography (SPECT) correspond to those obtained by echocardiography. METHODS: Eight-frame gated SPECT with a 2-day technetium-99m tetrofosmin acquisition protocol was used. End-diastolic (EDV) and end-systolic (ESV) volumes were measured automatically with the quantitative gated SPECT algorithm. Reversible myocardial hypoperfusion was evaluated with a 16-segment, 4-point perfusion score model. LV volumes at rest were also measured with echocardiography by use of the biplane Simpson rule. RESULTS: Twenty-two patients (group 1) showed normal perfusion and normal LV systolic function, whereas 33 patients (group 2) had evident coronary heart disease with reversible hypoperfusion. Patients in group 2 had greater EDV and ESV than those in group 1 both at rest and poststress. A greater reduction in ESV from poststress to rest was seen in group 2, which resulted in a slight increase in ejection fraction for patients in this group. The change in ESV from poststress to rest was significantly influenced by the degree of reversible hypoperfusion and by the change in heart rate from poststress to rest. We found a good correlation between LV volumes measured with gated SPECT and echocardiography. CONCLUSION: LV volume measurements with quantitative gated SPECT are comparable to those obtained with echocardiography. Patients with ischemic heart disease have greater LV volumes than patients with normal perfusion. Exercise-augmented adenosine infusion in patients with ischemic heart disease affects ESV more than EDV. This response is partly modulated by the degree of reversible hypoperfusion and possibly represents a minor degree of poststress stunning.     

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.     

Quantitative evaluation of a comprehensive motion, resolution, and attenuation correction program: Initial experience

Background  Tomographic myocardial imaging is widely used in the diagnosis and evaluation of patients with coronary artery disease. However, its specificity remains suboptimal because of attenuation, resolution, and motion artifacts. The purpose of this study was to optimize and assess the value of attenuation, blur, and motion correction of myocardial single photon emission computed tomographic data. Methods and Results  Forty-seven studies were selected for analysis to provide 3 patient groups. Group A consisted of 18 patients with a low likelihood of coronary artery disease who were used to construct a quantitative normal database and assess changes in the normal bull’s-eye produced by filtering and by attenuation correction. Group B consisted of 13 patients with a high probability of normal results, and group C consisted of 16 patients with coronary artery disease defined on angiography. The effects of attenuation correction, especially in conjunction with RESTORE (a depth-dependent deblurring filter), have been quantitated. Analysis indicates a trend to improved sensitivity and specificity for detecting individual vessel disease in this retrospective study. The motion correction program was successfully applied to 93% of patients but detected significant motion requiring correction in only 11 (24%) patients. Conclusion  This preliminary retrospective study indicates a potential for improved myocardial single photon emission computed tomography imaging with the use of attenuation and motion correction together with a restorative deblurring filter. Confirmation by a multicenter study and larger patient numbers remain necessary to assess fully the prospective value of the technique.