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

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

Left ventricular function evaluation using radionuclide methods in the intensive coronary care unit

We describe an adapted first-transit (FT) technique to perform left ventricular ejection fraction (LVEF) measurements on patients with Swan-Ganz catheters in the intensive cardiac care unit (ICCU). The radionuclide is introduced directly into the right pulmonary artery through the catheter. High-quality images of the left ventricle are obtained owing to minimal activity in the right ventricle and left lung. LVEF measurements obtained by FT compared well with measurements obtained from gated blood pool studies (r = 0.91) but gave consistently lower values. The adapted FT method improves LVEF determination and left-ventricular wall motion evaluation in the ICCU patient.     

First-pass anger camera radiocardiography: biventricular ejection fraction, flow, and volume measurements

First-pass (FP) right and left ventricular ejection fraction results were compared with equilibrium radiocardiographic (ER) measurements, and FP left ventricular ejection fraction (LVEF) values were compared with biplane contrast angiographic (CA) measurements in 13 patients with and seven patients without regurgitant valvular disease. Regurgitant fractions were calculated from differences between the FP right and left ventricular stroke volumes. Ejection fractions determined by FP were precise (mean CV = 9.6% RVEF, 13.4% LVEF). Mean LVEF by FP and ER were essentially identical, and both were lower than by CA. LVEF(FP) correlated with LVEF by ER and CA (r = 0.88, p less than 0.001). Mean RVEF by both FP and ER were also correlated (r = 0.82, p less than 0.001). There was correlation between FP (corrected) and CA left ventricular stroke (r = 0.77), end-diastolic (r = 0.88), and end-systolic (r = 0.91) volumes, but underestimates were noted when uncorrected flows were used (r = 0.52-0.71). The FP regurgitant fraction measurements separated the patients with regurgitant valvular disease from those without and agreed well with CA grading of regurgitation.     

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

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

Improved accuracy in estimation of left ventricular function parameters from QGS software with Tc-99m tetrofosmin gated-SPECT: a multivariate analysis

The purpose of this study was to verify whether the accuracy of left ventricular parameters related to left ventricular function from gated-SPECT improved or not, using multivariate analysis. METHODS: Ninety-six patients with cardiovascular diseases were studied. Gated-SPECT with the QGS software and left ventriculography (LVG) were performed to obtain left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Then, multivariate analyses were performed to determine empirical formulas for predicting these parameters. The calculated values of left ventricular parameters were compared with those obtained directly from the QGS software and LVG. RESULTS: Multivariate analyses were able to improve accuracy in estimation of LVEF, EDV and ESV. Statistically significant improvement was seen in LVEF (from r = 0.6965 to r = 0.8093, p < 0.05). Although not statistically significant, improvements in correlation coefficients were seen in EDV (from r = 0.7199 to r = 0.7595, p = 0.2750) and ESV (from r = 0.5694 to r = 0.5871, p = 0.4281). CONCLUSION: The empirical equations with multivariate analysis improved the accuracy in estimating LVEF from gated-SPECT with the QGS software.     

The additive values of left ventricular function and extent of myocardium at risk to dipyridamole perfusion imaging for optimal risk stratification prior to vascular surgery.

Although the increased risk of cardiac complications in surgical patients with diminished left ventricular ejection fraction (LVEF) is well-established, this method has been supplanted in recent years by assessment of ischaemic burden using myocardial perfusion imaging (MPI). This study was conducted to determine if MPI and LVEF determination provide complementary or redundant information in preoperative evaluation of vascular surgery patients. A total of 101 patients were studied with dipyridamole MPI and radionuclide ventriculography before surgery. Single photon emission tomographic MPI images were scored for defect severity and categorized as either fixed or reflecting ischaemia. Resting left ventricular cavity was also categorized as normal or dilated. LVEF was subdivided into normal (> or = 50%) and abnormal (< 50%). Seventeen patients had cardiac events. Events were more frequent in patients with ischaemia, in patients with a LVEF < 50% and in those with dilated left ventricular chambers. The mean number of ischaemic segments was also higher in the cardiac event group. Higher event rates were seen when a combination of these factors was present. A history of myocardial infarct, congestive heart failure or coronary artery disease was also a significant predictor of subsequent events. Thus, both abnormal left ventricular function and extent of ischaemic myocardium have independent and complementary predictive power for cardiac events in vascular surgery patients.     

Scintigraphic diagnosis of postinfarction left ventricular aneurysm and the prediction of the residual left ventricular function after aneurysmectomy using ECG gated blood pool SPECT

The diagnostic accuracy of ECG gated blood pool SPECT (blood pool SPECT) for detecting and quantify postinfarction left ventricular aneurysm (LVA) was assessed in 49 patients with myocardial infarction and 15 control subjects. LVA, which was detected in 35 of 49 patients, was defined as a regional protrusion through a cardiac cycle in contrast ventriculography and as a non-contracting segment with a markedly delayed phase angle in the tomographic functional images derived from phase analysis. The blood pool SPECT technique showed a high sensitivity (100%), specificity (78.6%) and accuracy (93.3%) for detecting LVA and was very useful for precisely determining LVA location and sizing contractile and non-contractile volume of left ventricle in patients with LVA. Furthermore, left ventricular ejection fraction (LVEF) after the excision of LVA was predicted using preoperative pool SPECT images in 9 patients. The predicted LVEF was closely correlated with the measured LVEF after the operation (y = 1.09x-4.37, r = 0.87, p less than 0.01). Thus, gated blood pool SPECT can be a useful non-invasive technique not only for detecting and quantifying left ventricular aneurysm but also for predicting a residual left ventricular function after aneurysmectomy.     

Factor analysis of multigated cardiac blood pool scintigram for the measurement of left ventricular ejection fraction

Left ventricular ejection fraction (EF) was measured by factor analysis (FA) of multigated cardiac blood pool scintigram in 38 consecutive patients, and compared with that measured by the variable ROI method (EFVROI) with automated left ventricular contour detection. FA was automatically performed without operator intervention with a success rate of 100%. The correlation of EF with EFVROI was significant in the group of 22 patients with normal wall motion (r = 0.65, p less than 0.001), and the entire group of patients (r = 0.70, p less than 0.001), but not significant (p = 0.19) in the group of 16 patients with abnormal wall motion. In conclusion, left ventricular ejection fraction can be estimated by factor analysis of MUGA in patients with normal wall motion.     

Development and application of normal limits for left ventricular ejection fraction and volume measurements from 99mTc-sestamibi myocardial perfusion gates SPECT.

Gated SPECT is a reproducible method for assessing left ventricular volume (LVV) and left ventricular ejection fraction (LVEF) from 99mTc-sestamibi myocardial perfusion imaging studies. LVV and LVEF measurements by this approach correlate well with those obtained from other cardiovascular imaging techniques. Nevertheless, the lack of criteria for abnormal test findings has limited the potential clinical application of this new imaging technique. METHODS: Gated SPECT measurements were evaluated for 214 patients with a low Bayesian likelihood (< 10%) of coronary artery disease (CAD) before performance of 99mTc-sestamibi stress-rest myocardial perfusion SPECT. The patients were grouped into normotensive patients (n = 98), hypertensive patients without left ventricular hypertrophy (LVH) (n = 80), and hypertensive patients with LVH on resting electrocardiography (n = 36). Gated SPECT measurements for left ventricular end-diastolic volume (LVEDV) index, left ventricular end-systolic volume (LVESV) index, and LVEF were obtained according to a published method, using a modified Simpson's rule technique. RESULTS: Similar results were obtained for mean LVV and LVEF measurements between normotensive patients and hypertensive patients without LVH. Hence, these groups were combined (as group 1). By contrast, hypertensive patients with LVH (group 2), had significantly lower LVEF values (P = 0.01) and higher mean LVESV index values than normotensive patients (P = 0.03). Sex differences were marked: women had significantly higher mean resting LVEF values than men (P < 0.0001) and significantly lower mean resting LVEDV index values (P < 0.0001). A significant relationship was seen between LVEDV index and LVEF (r = -0.60; P < 0.0001) and between LVEDV index and heart rate (r = -0.26; P < 0.001). The normal limits were LVEF > or = 41% in men and > or = 49% in women, LVEDV index < or = 76 mL/m2 in men and < or = 57 mL/m2 in women, and LVESV index < or 38 mL/m2 in men and < or =26 mL/m2 in women. Among hypertensive patients, 22% with LVH had an abnormally low LVEF and 19% had an increased LVEDV index according to these test criteria. By contrast, no hypertensive patients without LVH had an abnormally low LVEF, and only 6% had volume abnormalities. CONCLUSION: Using a cohort of low-likelihood patients, we generated sex-specific normal limits for LVV and LVEF for myocardial perfusion gated SPECT. Application of these findings resulted in the detection of occult left ventricular dysfunction in approximately one fifth of hypertensive patients for whom concomitant LVH was found through resting electrocardiography. These normal limits can now be evaluated prospectively for their potential clinical value.     

Value of combined assessment of global and segmental ventricular contraction with right anterior oblique ECG-gated first-pass and left anterior oblique equilibrium radionuclide ventriculography

A semi-automated, variable-region-of-interest method of analysis was used to measure both global and segmental left ventricular (LV) and global right ventricular (RV) contraction with ECG-gated first-pass and equilibrium radionuclide ventriculography. Normal values were defined in 20 healthy volunteers, and in 24 symptomatic patients, the results were compared with right anterior oblique (RAO) contrast left ventriculography. The global LV ejection fraction (LVEF) obtained by equilibrium imaging in the left anterior oblique (LAO) projection correlated closely with the results obtained by the gated first-pass method in the RAO projection (r = 0.95) and those obtained with contrast left ventriculography (r = 0.94); furthermore, the interobserver variability was small (r = 0.985). The normal values for LVEF obtained using radionuclide techniques and contrast ventriculography did not differ, but with the equilibrium radionuclide method, the RV ejection fraction (RVEF) values were underestimated in comparison to those obtained by the RAO gated first-pass technique. In five patients with localised inferior segmental akinesis at contrast angiography, the RAO first-pass cine display demonstrated a corresponding wall-motion abnormality in all cases, but LAO equilibrium cine displays did so in only one out of five patients. For segmental quantitation of LV contraction, a computer programme defined the ventricular edge, divided the RAO LV images into five segments and determined both the segmental area contraction (SAC) and the counts-based segmental ejection fraction (SEF). Radionuclide SAC measurements correlated very strongly with SEF measurements (r = 0.94-0.99). Both radionuclide SAC and radionuclide SEF correlated well with contrast angiographic SAC, except in the inferobasal segment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Background correction in first-pass radionuclide angiography: comparison of several approaches

This study was designed to test the comparative accuracy of several commonly used background correction techniques in first-pass radionuclide angiography (FPRNA). Thirty patients underwent FPRNA and single plane contrast angiography (CA) within 1 hr of each other. The left ventricular ejection fractions (LVEF) calculated from the different background subtraction approaches to FPRNA were compared to the CA LVEF. When applied to a representative cycle, a horseshoe-shaped background region of interest (BKROI) underestimated LVEF (p less than 0.005, r = 0.91, s.e.e. = 0.06) while a ring shaped BKROI adjusted at end-systole for aortic valve motion insignificantly overestimated LVEF (p = NS, r = 0.91, s.e.e. = 0.07). A lung background approach applied to a representative cycle gave the best correlation with CA (p = NS, r = 0.96, s.e.e. = 0.04). Without using a representative cycle, time-activity curves from a horseshoe-shaped BKROI and the LV ROI were created and the LV curve was normalized to the peak counts in the BKROI curve. LVEF calculated from the normalized curve correlated favorably with CA LVEF (p = NS, r = 0.91, s.e.e. = 0.08). The influence of some recently described improvements in representative cycle generation are also documented.     

Improved accuracy in estimation of left ventricular function parameters from QGS software with Tc-99m tetrofosmin gated-SPECT: a multivariate analysis

The purpose of this study was to verify whether the accuracy of left ventricular parameters related to left ventricular function from gated-SPECT improved or not, using multivariate analysis.Methods: Ninety-six patients with cardiovascular diseases were studied. Gated-SPECT with the QGS software and left ventriculography (LVG) were performed to obtain left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Then, multivariate analyses were performed to determine empirical formulas for predicting these parameters. The calculated values of left ventricular parameters were compared with those obtained directly from the QGS software and LVG.Results: Multivariate analyses were able to improve accuracy in estimation of LVEF, EDV and ESV. Statistically significant improvement was seen in LVEF (from r=0.6965 to r=0.8093, p<0.05). Although not statistically significant, improvements in correlation coefficients were seen in EDV (from r=0.7199 to r=0.7595, p=0.2750) and ESV (from r=0.5694 to r=0.5871, p=0.4281).Conclusion: The empirical equations with multivariate analysis improved the accuracy in estimating LVEF from gated-SPECT with the QGS software.     

A comparison of two radionuclide ejection-fraction techniques with contrast angiography in ischemic heart disease and valvular heart disease

First-pass radionuclide angiography (FPRA) in the 30 degree right anterior oblique and equilibrium gated radionuclide angiography (EGNA) in the 45 degree left anterior oblique were used for quantitative measurements of left ventricular ejection fraction (LVEF). Equipment used was a 400T gamma-camera interfaced with a Simis III Informatek computer. The results were compared with contrast angiography (CA). The aim of this study was to determine the sensitivity of both radionuclide techniques. The present data are based on 65 patients in whom CA and EGNA were performed. In 47 patients both FPRA and EGNA were performed. Results suggested that in ischemic heart disease (IHD) and valvular heart disease (VHD) the EGNA technique is well correlated with CA (r = 0.9 and 0.73, respectively). FPRA correlated well only with CA in IHD (r = 0.86), but not in VHD (r = 0.18). This study indicates that both FPRA and EGNA are sensitive, noninvasive techniques for measuring ejection fraction in IHD, while in VHD, EGNA is more sensitive technique than FPRA.     

Repeatability of treadmill exercise ejection fraction and wall motion using technetium 99m-labeled sestamibi first-pass radionuclide ventriculography

Background  

Peak treadmill exercise radionuclide ventriculography (RVG) with technetium 99m has recently been validated for determination of left ventricular ejection fraction (LVEF). However, the repeatability of this technique for determination of both LVEF and regional wall motion has not been reported.     

Ischaemic related transitory left ventricular dysfunction in 201Tl gated SPECT

AIM: To report our data concerning the changes in post-stress and at-rest left ventricular ejection fraction and ventricular volumes in patients with thallium gated SPECT. METHODS: Post-stress and at-rest thallium gated SPECT was performed in 629 consecutive patients; left ventricular ejection fraction (LVEF), left ventricular volumes and quantitative perfusion data were obtained. Transitory left ventricular dysfunction was diagnosed when post-stress LVEF did not increase at least 5% from LVEF at-rest. RESULTS: In all patients post-stress LVEF was 64%+/-17 while at-rest LVEF was 66%+/-15 (P=0.6). Post-stress end diastolic volume (EDV) was 142 ml+/-7, at-rest EDV was 141 ml+/-92 (P=0.57), post-stress end systolic volume (ESV) was 54 ml+/-51 and at-rest ESV was 56 ml+/-59 (P=0.38). Data from the perfusion study were used to divide patients into three groups: normal patients (group I), patients with total or partially reversible defects (group II) and patients with fixed defects (group III). In group I and group III patients LVEF at-rest was lower than post-exercise (LVEF 75%+/-11 vs 81%+/-10 (P<0.001) and 57%+/-16 vs 60%+/-18 (P=0.025)), respectively. Patients in group II had a higher at-rest LVEF than post-exercise (LVEF 66%+/-14 vs 64%+/-16 (P=0.003)). While the left ventriuclar volumes in group I and III patients decreased with exercise, group II patients had increased post-stress ESV. CONCLUSIONS: Post-stress and at-rest LVEF are similar when all patients are considered but significant differences appear when patients are divided according to the results of the perfusion study. Normal and fixed defect patients have increased post-exercise LVEF. Patients with reversible defects have decreased LVEF, which is largely due to an increased ESV. Transitory left ventricular dysfunction is related to the presence of reversibility and may benefit from revascularization.     

Clinical usefulness of ultrashort-lived iridium-191m from a carbon-based generator system for the evaluation of the left ventricular function

Ultrashort-lived 191mIr (4.96 sec; 63-74 and 129 keV photons) is potentially advantageous for first-pass radionuclide angiocardiography, offering the opportunity to perform repeat studies with very low absorbed radiation dose to the patient. Left ventricular (LV) first-pass studies were performed in 72 patients with 191mIr from a new bedside 1.3 Ci (48.1 GBq) 191Os/191mIr generator system using an activated carbon support that offers high 191mIr yields (15-18%) and consistent low 191Os breakthrough (2-4 x 10(-4)%/bolus). Using a single crystal digital gamma camera, uncorrected end-diastolic counts in the left ventricular representative cycle ranged from 10 up to 30 k counts. The reproducibility of repeated LV ejection fraction (LVEF) determination at 2-min intervals in 50 patients was r = 0.97, mean diff. = 2.08 +/- 1.55 EF units. Comparison between 191mIr (80-120 mCi; 2,960-4,400 MBq) and 99mTc (20-25 mCi; 750-925 MBq) LV count rates indicates a 3 wk useful shelf life of this new generator system for cardiac studies. Iridium-191m determined LVEF correlated closely with 99mTc determined LVEF in 32 patients (r = 0.96, mean diff. = 1.87 +/- 1.23 EF units). Parametric images for LV wall motion analysis were comparable with both isotopes. We conclude that rapid, repeat, and reproducible high count rate first-pass left ventricular studies can be obtained with 191mIr from this new 191Os/191mIr generator system using a single crystal digital gamma camera.     

Comparison of post-stress ejection fraction and relative left ventricular volumes by automatic analysis of gated myocardial perfusion single-photon emission computed tomography acquired in the supine and prone positions

Background  We have previously described an automatic method for measuring left ventricular ejection fraction (LVEF) for myocardial perfusion single-photon emission computed tomography (SPECT). The repeatability of this method has not been previously described. Methods and Results  This study compares LVEF and relative end-systolic and end-diastolic volumes assessed from myocardial perfusion SPECT by our automatic method in 180 consecutive patients undergoing gated myocardial perfusion SPECT with injection of ^99mTc-labeled sestamibi in whom the acquisitions were performed sequentially in supine and prone positions. The algorithm operated completely automatically in the prone and supine positions in 178 of the 180 patients. Very high correlations were observed for LVEF (r=0.93), relative left ventricular end-systolic volume (r=0.98), and relative left ventricular end-diastolic volume (r=0.97). The mean paired absolute difference between LVEFs in the prone and supine position was 3.8±3.2, for left ventricular end-systolic volume was 4.9±4.8 ml, and for left ventricular end-diastolic volume was 7.4±6.7 ml. When patients were classified by the extent and severity of stress perfusion defect, there was no significant difference in repeatability for the measurements in any category. Conclusions  Our algorithm for automatic quantification of LVEF and relative end-systolic and end-diastolic volumes from gated ^99mTc sestamibi myocardial perfusion SPECT is repeatable. When performed in the prone position, values of ejection fractions and ventricular volumes are essentially identical to those obtained in the supine position.     

Scintigraphic evaluation of the peak systolic pressure-end-systolic volume relation: comparison with invasive left ventricular contractile indexes]

We calculated the slope of peak systolic pressure-end-systolic volume relation (P/V slope) and the ratio of peak systolic pressure to end-systolic volume (P/V ratio) using radionuclide ventriculography and indirect sphygmomanometry to evaluate left ventricular contractility, and to assess the usefulness of these indexes, we compared them with mean VCF, LVEF, ESVI and ESS/ESVI using cardiac catheterization. Subjects were 12 patients who had received both radionuclide ventriculography and cardiac catheterization within a two weeks period. Left ventricular end-systolic volume and peak blood pressure were measured at 3 different points, one in the control state and the other two at two different hemodynamic states during infusion of Methoxamine. We defined P/V slope as the slope of the regression line of peak systolic pressure-end-systolic volume relation, and P/V ratio as the ratio of peak systolic pressure to left ventricular end-systolic volume at control. Left ventricular volume was measured by the non-gated-SPECT method and changes of the left ventricular volume was measured by the multigate method. P/V slope was correlated exponentially with mean VCF, LVEF and ESVI (y = 0.34.e1.9x, r = 0.86, p less than 0.001 for mean VCF; y = 0.25.e0.041x, r = 0.83, p less than 0.001 for LVEF; y = 7.8.e-0.028x, r = 0.88, p less than 0.001 for ESVI), and correlated linearly with ESS/ESVI (y = 1.6x-3.7, r = 0.88, p less than 0.001). P/V ratio was also correlated exponentially with mean VCF, LVEF and ESVI (y = 0.47.e1.4x, r = 0.86, p less than 0.001 for mean VCF; y = 0.35.e0.032x, r = 0.86, p less than 0.001 for LVEF; y = 4.8.e-0.021x, r = 0.87, p less than 0.001 for ESVI), and correlated linearly with ESS/ESVI (y = 1.2x-2.6, r = 0.83, p less than 0.001). We concluded that P/V slope and P/V ratio were useful indexes to evaluate left ventricular contractility noninvasively.     

Probe radiocardiography: validation of a technique to routinely determine left ventricular ejection fraction.

We investigated the probability of obtaining a valid radiocardiogram with the first commercially available cardiac probe and a peripheral injection of the radiopharmaceutical. Measurements of left ventricular ejection fraction (LVEF) were obtained in a series of 15 patients undergoing cardiac catheterization. Probe LVEF determinations using central, peripheral and rapid sequential injections correlated well with each other and with ventriculography (r = .88--.98). By documenting its accuracy and precision, this study confirms the validity of a new technique for measuring LVEF.     

Evaluation of left and right ventricular functional parameters with automatic edge detection program of ECG gated blood SPET

An analysis program for ECG gated, blood pool, single photon emission tomography (SPET GBP) is available. This program permits the automatic evaluation of left and right ventricular function, but its reliability has not been thoroughly assessed. The objective of this investigation was to examine the reliability of the parameters derived from SPET GBP. Fifty-three patients who had undergone both SPET GBP and planar, ECG gated, blood pool scintigraphy (planar GBP) were enrolled in the study. Planar GBP was performed with a single-headed gamma camera. From a left anterior oblique projection, data were acquired at 24 frames/cardiac cycle with ECG gating during the equilibrium state. SPET GBP was carried out utilizing a triple-headed gamma camera, with 60 projection views over 360 degrees, with 60 s per view, in 16 frames/cardiac cycle. Left ventricular ejection fraction (LVEF) and right ventricular ejection fraction (RVEF) were calculated by using the analysis program. The reproducibility of these values and the correlation between SPET and planar GBP were assessed. To evaluate the effect of cut-off frequencies of a Butterworth filter, six different cut-off frequencies (order=8, 0.3-1.0 Nyquist) were tested with data obtained from 12 patients. The reproducibility of LVEF by SPET GBP was satisfactory (intra-observer, r=0.95; inter-observer, r=0.96), whereas reproducibility of RVEF by SPET GBP was fair (intra-observer, r=0.83; inter-observer, r=0.83). LVEF with SPET GBP was well correlated (y=1.1x+6.62, r=0.85, P<0.01) with LVEF readings of planar GBP. However, LVEF with SPET GBP was overestimated (mean difference of 12) in comparison with that of planar GBP. The RVEF derived from SPET GBP showed poor correlation (y=0.52x+33, r=0.53, P<0.01) with planar GBP. No significant effect of cut-off frequencies of Butterworth filters was evident in the calculation of LVEF and RVEF (P=0.48 and 0.67) with SPET GBP. It is concluded that SPET GBP with QBS is useful for the evaluation of LVEF. However, measurement of the RVEF showed lower reproducibility compared with measurement of the LVEF.