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.     

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.     

Evaluation of left ventricular endocardial volumes and ejection fractions computed from gated perfusion SPECT with magnetic resonance imaging: Comparison of two methods

BACKGROUND: Two methods of computing left ventricular volumes and ejection fraction (EF) from 8-frame gated perfusion single photon emission computed tomography (SPECT) were compared with each other and with magnetic resonance (MR) imaging. METHODS AND RESULTS: Thirty-five subjects underwent 8-frame gated dual-isotope SPECT imaging and 12- to 16-frame gated MR imaging. Endocardial boundaries on short-axis MR images were hand traced by experts blinded to any SPECT results. Volumes and EF were computed with the use of Simpson's rule. SPECT images were analyzed for the same functional variables with the use of 2 automatic programs, Quantitative Gated SPECT (QGS) and the Emory Cardiac Toolbox (ECTb). The mean difference between MR and SPECT EF was 0.008 for ECTb and 0.08 for QGS. QGS showed a slight trend toward higher correlation for EF (r = 0.72, SE of the estimate = 0.08) than ECTb (r = 0.70, SE of the estimate = 0.09). For both SPECT methods, left ventricular volumes were similarly correlated with MR, although SPECT volumes were higher than MR values by approximately 30%. CONCLUSIONS: QGS and ECTb values of cardiac function computed from 8-frame gated perfusion SPECT correlate very well with each other and correlate well with MR. Averaged over all subjects, ECTb measurements of EF are not significantly different from MR values but QGS significantly underestimates the MR values.     

Transient postischemic stunning evaluation by stress gated Tl-201 SPECT myocardial imaging: Effect on systolic left ventricular function

BACKGROUND: Transient postischemic stunning (TIS) has been reported in images obtained (1/2) to 1 hour after stress with technetium 99m tracers but has not been investigated in images obtained shortly after stress with thallium 201. We also quantified the global extent and severity of TIS, which has not been done previously. METHODS AND RESULTS: We evaluated 82 patients with either treadmill or dobutamine stress Tl-201 myocardial perfusion imaging. Images were semiquantitatively examined with a 20-segment model. The extent and severity of myocardial ischemia and TIS were assessed by the summed difference score from the early and delayed scores of perfusion, wall motion (WM), and wall thickening (WT). The mean left ventricular ejection fraction (LVEF) was significantly lower in early images than in delayed images in patients with ischemia (P <.01), TIS by WM (P <.001), and TIS by WT (P <.001), and the LVEF difference was more significantly different as the summed difference score of perfusion, WM, or WT increased. No significant LVEF difference was seen in patients with ischemia who did not have TIS. CONCLUSIONS: In stress gated Tl-201 single photon emission computed tomography myocardial perfusion imaging, early TIS is frequently seen in patients with ischemia and is equivalently detected by WM and WT assessments. Significant exercise-induced transient left ventricular global dysfunction is associated with more severe and extensive ischemia and can be predicted by the measurement of the extent and severity of TIS from the same images.     

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.     

Day-to-day variability of global left ventricular functional and perfusional measurements by quantitative gated SPECT using Tc-99m tetrofosmin in patients with heart failure due to coronary artery disease

BACKGROUND: Although myocardial gated single photon emission computed tomography (SPECT) is routinely used for functional measurements in patients with coronary artery disease (CAD) and heart failure, day-to-day variability of left ventricular ejection fraction (LVEF), left ventricular (LV) volumes, and global perfusion scoring has not yet been investigated. METHODS AND RESULTS: In 20 consecutive patients with CAD and an LVEF lower than 40% who routinely underwent a resting tetrofosmin gated SPECT study, we performed an additional gated SPECT study at rest 1 to 5 days later under the same circumstances. LV volumes and LVEF were calculated from the gated SPECT data by commercially available software (QGS). Myocardial perfusion was scored visually by use of a 20-segment, 5-point scoring method. For global LV function and perfusion, agreement between data was investigated by use of Bland-Altman plotting. The 95% limits of agreement found by Bland-Altman analysis were -0.9% +/- 6.0% for LVEF, 3 +/- 20 mL for LV end-diastolic volume, and 4 +/- 20 mL for LV end-systolic volume. CONCLUSION: In CAD patients with an LVEF lower than 40%, day-to-day variability of measurements of global myocardial function and perfusion is quite similar to interobserver and intraobserver variability. Day-to-day variability of global LV functional parameters obtained by gated cardiac SPECT is fairly small, which indicates that myocardial gated SPECT can be used in daily clinical practice to determine changes in global LV function and perfusion over time in patients with diminished LV function.     

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.     

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.     

Assessment of left ventricular diastolic function with electrocardiography-gated myocardial perfusion SPECT: Comparison with multigated equilibrium radionuclide angiography

BACKGROUND: Technetium-labeled myocardial perfusion tracers allow the simultaneous assessment of myocardial perfusion and left ventricular function by electrocardiography (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT). This study evaluates left ventricular systolic and diastolic function by ECG-gated SPECT with the use of higher framing (32 frames per cardiac cycle) data acquisition. METHODS AND RESULTS: After receiving an injection of technetium 99m tetrofosmin, 48 patients with cardiac diseases were examined by ECG-gated myocardial perfusion SPECT with a 3-headed gamma camera. During gated data collection, 32 frames per cardiac cycle were acquired over 360 degrees in 60 steps, each of which consisted of 60 beats. Immediately thereafter, the 32 frames taken at each projection angle were combined into 16-frame and 8-frame data sets. Left ventricular end-diastolic volume (LVEDV, in milliliters), left ventricular end-systolic volume (LVESV, in milliliters), and left ventricular ejection fraction (LVEF, percentage) were automatically calculated from the 32-frame, 16-frame, and 8-frame gated data sets. Left ventricular time-volume curves from the 3 data sets were generated by Fourier curve fitting analysis with the use of 3 harmonics, and then peak filling rate (PFR, per second) was measured. Twenty-nine patients also underwent multigated equilibrium radionuclide angiography (ERNA) to determine the LVEF and PFR. Combining the 32-frame data into 16-frame and 8-frame data sets from the 48 patients generated a smaller LVEDV and a larger LVESV, and LVEF was significantly lower in accordance with the decreasing number of frames. Compared with ERNA studies (n = 29), the Bland-Altman method showed underestimated LVEFs and larger 95% limits of agreement in lower framing gated SPECT. CONCLUSIONS: Left ventricular functional parameters obtained from 32-frame gated SPECT correlated closely with those determined by ERNA studies. ECG-gated SPECT with 32-frame data can provide comprehensive information with which to evaluate many types of cardiac diseases.     

Left ventricular ejection fraction and volumes from gated single photon emission tomographic myocardial perfusion images: Comparison between two algorithms working in three-dimensional space

Objective. Two different algorithms operating in three-dimensional space, one dependent on surface detection developed at Cedars-Sinai Medical Center (CS) and another dependent on statistical parameters and developed at Stanford University Medical School (SU), were compared in the same patients to assess the left ventricular volumes and the left ventricular ejection fractions (LVEFs) from gated single-photon emission tomography (SPECT) myocardial perfusion images.Methods. Perfusion SPECT images gated in eight time bins were recorded in 40 patients with coronary artery disease 60 minutes after the injection of 925 MBq^99mTc-labeled tetrofosmin at rest. The LVEF values were validated against planar gated ^99mTc-labeled blood pool studies (ERNA).Results. The software success rates were 95% (38/40 patients) for CS and 100% for SU. Agreement between LVEFs measured with CS and SU and agreement between both methods and ERNA were excellent (LVEF_CS = 0.89LVEF_SU + 6.21, r = 0.93; LVEF_SU = 0.92LVEF_ERNA + 0.99, r = 0.94; and LVEF_CS = 0.88LVEF_ERNA + 4.58, r = 0.93). Bland-Altman plots showed that differences between LVEFs from SU and CS and from ERNA were similar across a wide range (20% to 80%) of LVEF values. No relationship between these differences and the severity of perfusion defects was observed. For left ventricular volumes, linear regression analysis showed an excellent correlation between both methods (end-diastolic volume R = 0.97 end-systolic volume R = 0.98), but systematically higher values were obtained with SU (p = 0.013).Conclusion. Measurements of LVEF obtained with CS and SU correspond well with those from the standard, ERNA, even in patients with severe perfusion defects. A close relationship is observed between SU and CS when left ventricular volumes are considered. Measurements of LVEF (and left ventricular volumes) should be considered as an integral part of myocardial perfusion studies whenever possible.     

Identification of exercise-induced left ventricular systolic and diastolic dysfunction using gated SPECT in patients with coronary artery disease

BACKGROUND: We investigated whether poststress left ventricular dysfunction in patients with coronary artery disease may be confirmed at 30 minutes after exercise using newly modified quantitative gated single photon emission computed tomography (QGS) software that can evaluate systolic and diastolic function. METHODS AND RESULTS: In this study 28 control subjects, 26 patients with angina pectoris (AP), and 27 patients with old myocardial infarction (MI) who had undergone revascularization were included. Same-day exercise/rest gated technetium 99m tetrofosmin single photon emission computed tomography was performed. QGS was used with a temporal resolution of 32 frames per R-R interval, and a left ventricular volume curve was reconstructed. From the fitted volume curve and its first derivative curve, we derived the ejection fraction (EF), peak ejection rate (PER), peak filling rate (PFR), and time to PFR (TPFR). In patients with AP and MI, the values for EF, PER, and PFR were lower after stress than at rest. TPFR was significantly prolonged in patients with MI after stress. In control subjects, EF, PER, PFR, and TPFR were not changed. CONCLUSIONS: Modified QGS software successfully indicated the changes in systolic and diastolic function. In patients with AP and MI, poststress systolic and diastolic dysfunction was identified 30 minutes after exercise.     

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.     

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.     

Evaluation of left ventricular mechanical dyssynchrony as determined by phase analysis of ECG-gated SPECT myocardial perfusion imaging in patients with left ventricular dysfunction and conduction disturbances

Background  Cardiac resynchronization therapy (CRT) is approved for the treatment of patients with advanced systolic heart failure and evidence of dyssynchrony on electrocardiograms. However, a significant percentage of patients do not demonstrate improvement with CRT. Echocardiographic techniques have been used for more accurate determination of dyssynchrony. Single photon emission computed tomography (SPECT) myocardial perfusion imaging has not previously been used to evaluate cardiac dyssynchrony. The objective of this study is to evaluate mechanical dyssynchrony as described by phase analysis of gated SPECT images in patients with left ventricular dysfunction, conduction delays, and ventricular paced rhythms. Methods and Results  A novel count-based method is used to extract regional systolic wall thickening amplitude and phase from gated SPECT images. Five indices describing the phase dispersion of the onset of mechanical contraction are determined: peak phase, phase SD, bandwidth, skewness, and kurtosis. These indices were determined in consecutive patients with left ventricular dysfunction (n=120), left bundle branch block (n=33), right bundle branch block (n=19), and ventricular paced rhythms (n=23) and were compared with normal control subjects (n=157). Phase SD, bandwidth, skewness, and kurtosis were significantly different between patients with left ventricular dysfunction, left bundle branch block, right bundle branch block, and ventricular paced rhythms and normal control subjects (all P<.001) Peak phase was significantly different between patients with right ventricular paced rhythms and normal control subjects (P=.001). Conclusions  A novel SPECT technique for describing left ventricular mechanical dyssyn-chrony has been developed and may prove useful in the evaluation of patients for CRT. This study was funded in part by a research grant from the Medtronic-Duke Strategic Alliance, of which Dr Borges-Neto is the primary investigator.     

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

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

Evaluation of mechanical dyssynchrony and myocardial perfusion using phase analysis of gated SPECT imaging in patients with left ventricular dysfunction

Background. Using phase analysis of gated single photon emission computed tomography (SPECT) imaging, we examined the relation between myocardial perfusion, degree of electrical dyssynchrony, and degree of SPECT-derived mechanical dyssynchrony in patients with left ventricular (LV) dysfunction. Methods and Results. We retrospectively examined 125 patients with LV dysfunction and ejection fraction of 35% or lower. Fourier analysis converts regional myocardial counts into a continuous thickening function, allowing resolution of phase of onset of myocardial thickening. The SD of LV phase distribution (phase SD) and histogram bandwidth describe LV phase dispersion as a measure of dyssynchrony. Heart failure (HF) patients with perfusion abnormalities have higher degrees of dyssynchrony measured by median phase SD (45.5° vs 27.7°, P<.0001) and bandwidth (117.0° vs 73.0°, P=.0006). HF patients with prolonged QRS durations have higher degrees of dyssynchrony measured by median phase SD (54.1° vs 34.7°, P<.0001) and bandwidth (136.5° vs 99.0°, P=.0005). Mild to moderate correlations exist between QRS duration and phase analysis indices of phase SD (r=0.50) and bandwidth (r=0.40). Mechanical dyssynchrony (phase SD >43°) was 43.2%. Conclusions. HF patients with perfusion abnormalities or prolonged QRS durations have higher degrees of mechanical dyssynchrony. Gated SPECT myocardial perfusion imaging can quantify myocardial function, perfusion, and dyssynchrony and may help in evaluating patients for cardiac resynchronization therapy. (J Nucl Cardiol 2008;15:663-70.) This study was funded by a research grant from the Medtronic-Duke Strategic Alliance, and Dr Trimble is the primary investigator.     

Heterogeneity of myocardial wall motion and thickening in the left ventricle evaluated with quantitative gated SPECT

BACKGROUND: Global and regional ventricular function may be evaluated by using gated myocardial perfusion single photon emission computed tomography (SPECT). This study investigated two parameters of regional contraction of the left ventricle, segmental wall motion (WM) and wall thickening (WT), to determine their similarity and disparity in each myocardial segment in patients with normal myocardial perfusion. METHODS AND RESULTS: Thirty-five patients with normal myocardial perfusion and cardiac function (mean left ventricular ejection fraction, 62.6%+/-8.8%) were included in this study. A 1-day stress/rest protocol was used as a means of acquiring technetium 99m (Tc-99m) sestamibi gated SPECT protocol for each patient. A commercially available software package for quantitative gated SPECT (QGS) was used to generate cine loop three-dimensional surface display and SPECT images. The left ventricle was divided into 9 segments to score WM and WT (on a scale of 0 to 4, with 0 being normal and 4 being severely reduced) by 6 independent observers. The WM score was significantly higher than the WT score in the septum, whereas the WM score was lower than the WT score in the inferior segment. Similar WM and WT scores were observed in the remaining segments. CONCLUSIONS: Heterogeneous myocardial WM and WT were observed by using QGS software. These findings suggest that different criteria are required in each segment to evaluate segmental WM and WT by means of gated myocardial perfusion SPECT.     

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.     

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.     

TI-201 washout rate in remote normal regions in patients with prior myocardial infarction and left ventricular remodeling

BACKGROUND: Myocardial characteristics of remote normal regions in patients with myocardial infarction (MI) and left ventricular (LV) remodeling have not been fully elucidated. Thus, we investigated this issue from the viewpoint of myocardial Tl-201 dynamics. METHODS AND RESULTS: In 14 patients with prior anterior MI, 10 with inferior MI, and 14 age-matched patients with atypical chest pain served as controls; exercise stress Tl-201 SPECT and cardiac catheterization were performed. Tl-201 washout rate was calculated for 8 myocardial segments, and LV end-diastolic volume index was obtained as a parameter of LV remodeling. LV end-diastolic volume index was greater in anterior MI patients than in control patients; in contrast, no significant difference was observed between inferior MI patients and control patients. The washout rate in remote normal regions was significantly less in anterior MI patients than in the corresponding segments in control patients (39.8% +/- 8.7% vs 48.4% +/- 4.4%, P < .01). There was no significant difference between inferior MI patients and control patients (43.6% +/- 6.9% vs 47.8% +/- 4.5%). CONCLUSIONS: Reduced Tl-201 washout rates in remote normal regions are found in patients with anterior MI and LV remodeling. Subclinical myocardial ischemia during exercise in remote normal regions exists and may be related to the pathologic condition of such LV walls.