Spontaneous variability of left ventricular ejection fraction assessed with the Cardioscint.

A miniature, non-imaging caesium iodide nuclear probe optically coupled to a photodiode (the 'Cardioscint') has been developed which, in conjunction with a modified personal computer, is capable of continuous on-line monitoring of left ventricular function and ST-segment level at the bedside. The purpose of this study was to assess the variability in ejection fraction over periods of time and to compare this variability with that of equilibrium gamma camera radionuclide ventriculography. Ten normal volunteers (nine male) of mean (S.D.) age 49 (10) years underwent semisupine radionuclide ventriculography using both gamma camera and Cardioscint in randomized order. The gamma camera recorded four consecutive acquisitions (mean of 7.2 min each) and the Cardioscint, using a 20 s acquisition time, recorded left ventricular function over 35 min per subject. The mean ejection fraction of the group by gamma camera was 52 (7)% and by Cardioscint was 54 (5)%. When the variability in ejection fraction by gamma camera was compared with the Cardioscint averaged over corresponding time periods (i.e. an average of 7.2 min), the mean coefficient of variation of the camera was 5.0% versus 2.9% for the probe system. Individual 20-s probe acquisitions over the total study duration (reflecting the short-term variability of the system) had a coefficient of variation of 5.1%. Thus the Cardioscint provides a stable continuous recording of ejection fraction. These volunteer data provide a basis for interpretation of data acquired in the clinical situation.     

Left ventricular ejection fraction determined with the nuclear stethoscope, gamma camera and contrast ventriculography

Left ventricular ejection fractions (EF) were measured with a nuclear stethoscope (NSt, beat-to-beat and ECG gated summation method) and contrast ventriculography (VG) immediately following one another (IFOA) (r X 0.96 and 0.95, respectively, n = 13). NSt and ECG gated gamma camera (MUGA) recordings IFOA were compared (r = 0.97 and 0.96, respectively, n = 23) as were non-IFOA recordings (r = 0.90 and 0.91, respectively, n = 13). Correlation between repeated NSt EF measurements gave: r = 0.91 (n = 22) for both methods. Paired NSt recordings in an invasive test situation (during invasive angiocardiography) and in a noninvasive situation (supine, 30 min of rest) gave for patients with EF less than 50 (mean +/- S.D.): EF invasive = 36 +/- 12, EF noninvasive = 41 +/- 13 (n = 4, p less than 0.05), and for patients with EF greater than or equal to 50: EF invasive = 59 +/- 7, EF noninvasive = 57 +/- 7 (n = 9, N.S.). The mean paired differences (EF noninvasive -EF invasive) in the low (less than 50) and high (greater than or equal to 50) EF range differed significantly: +5.3 versus -1.3, respectively (p less than 0.001). The recordings with the ECG-gated summation method gave similar results. The heart rate (beats min-1) in the noninvasive and invasive situation were (mean +/- S.D.): 68 +/- 11 and 78 +/- 16, respectively (p less than 0.01). We conclude that the patients were in a higher level of stress in the invasive situation. Accordingly ventricles with normal contractility (EF greater than or equal to 50) reacted with a slight increase in EF, and ventricles with compromised function (EF less than 50) reacted with a decrease in EF, compared to the values in the noninvasive situation. Incorporated in a correlation between MUGA and VG are, besides methodologically based differences, test-situation based systematical differences. Consequently the results of MUGA method should be given uncorrected. The results documents the accuracy and reliability of the NSt.     

Clinical validation of a miniature nuclear probe system for continuous on-line monitoring of cardiac function and ST-segment

A new, miniature cesium iodide/photodiode nuclear probe (the "Cardioscint") has been developed for continuous on-line measurement of left ventricular function and the ST-segment. Ejection fraction (EF) measurements in 77 patients were compared with gated equilibrium radionuclide ventriculograms. The probe was positioned over the left ventricle by first using a blind positioning algorithm and then by using the gamma camera. Background was measured both manually and automatically. There was good correlation between probe (positioned blind) and gamma camera EF with both manual (r = 0.80, n = 65) and automatic (r = 0.78, n = 66) backgrounds. Use of the gamma camera did not significantly alter the results. Correlation between the probe stroke counts and thermodilution-derived stroke index during atrial pacing in six subjects was also satisfactory (r = 0.69, n = 102). Thus, the Cardioscint is able to provide a reliable estimate of EF and can track rapid changes in cardiac volumes.     

A new method to measure thyroid uptake with a gamma camera without routine use of a standard source

PURPOSE: This study was designed to validate a reliable gamma camera-based method for measuring thyroid uptake. The method is based on a stable calibration procedure and does not require daily use of a standard source. In addition, the method is designed to overcome deadtime losses inherent in uptake probe measurements with iodine-123. METHODS: A calibration procedure was designed using I-123 capsules in a neck phantom and tested using two gamma cameras. Patient thyroid uptake measurements made with the proposed gamma camera method were correlated with measurements obtained using the traditional uptake probe technique. Image quality was compared between the low-energy, parallel-hole collimator used in this study and the pinhole collimator usually used for thyroid imaging. RESULTS: Capsule count rates measured using the gamma camera are linear with activity, and the calibration procedure is reproducible when tests are performed several months apart. Thyroid uptake measured with the gamma camera correlated closely (R2 > 0.9) with measurements made using the probe technique. Image quality with the low-energy parallel-hole collimator was comparable to that obtained with the pinhole collimator. CONCLUSIONS: The proposed camera-based method for measuring thyroid uptake is accurate and reproducible. It can be performed readily in conjunction with the routine scan procedure. Adoption of this technique reduces equipment requirements in the nuclear medicine department.     

Accuracy and reproducibility of left ventricular ejection fraction measurements using an ambulatory radionuclide left ventricular function monitor

The accuracy and reproducibility of a new ambulatory radionuclide detector system (the VEST) for ejection fraction measurement has not been fully validated. Thirty-six subjects, (19 volunteers and 17 patients) underwent repetitive bicycle exercise using sequences of both VEST monitoring and gamma camera imaging. A high intraclass correlation was noted for both absolute ejection fraction [0.84 (0.56, 0.95)] and delta ejection fraction [0.87 (0.63, 0.96)] during repeat VEST monitoring. The intraclass correlation for ejection fraction was comparable for data averaged over 30 sec versus 2 min. These correlations compared favorably to those obtained for assessment of absolute and delta ejection fraction as derived by gamma camera determination by the same computer operator (intraobserver variability), two different computer operators (interobserver variability), and during repeat exercise using gamma camera imaging. In concordance, correlations between VEST and gamma camera measurements were relatively high for both absolute ejection fraction (0.78 [0.61, 0.88]) and delta ejection fraction (0.63 [0.39, 0.79]). Thus, the VEST represents a reproducible means of measuring ejection fraction change during dynamic physical activity. Its accuracy in ejection fraction measurements is similar to gamma camera imaging during exercise testing.     

High count rate first-pass radionuclide angiography using a digital gamma camera

In this study, first-pass radionuclide angiography (FPRNA) was performed using a digital single-crystal gamma camera. Twenty-nine men and six women (ages 43-80, mean 61 yr) underwent FPRNA in the supine position immediately prior to cardiac catheterization. Total counts/sec in the whole field-of-view in the right ventricular phase were 150,352 +/- 26,006. Background uncorrected counts in the representative cycle were 7,651 +/- 2,527 at end-diastolie and 4,904 +/- 2,314 at end-systolie. A linear correlation between FPRNA left ventricular (LV) ejection fraction and contrast LV ejection fraction gave an r = 0.95 with an s.e.e. of 0.05. Analyses of intra- and interobserver variability gave r = 0.99 and 0.98 and an s.e.e. of 0.02 and 0.03, respectively. Spearman-Rank correlation coefficients between FPRNA and contrast angiographic wall-motion scores were greater than 0.8 for all walls, while sensitivity/specificity were 0.86/0.90, 0.76/1.00, 0.76/1.00 for anterior, apical, and inferior wall-motion abnormalities, respectively. We conclude that satisfactory counting statistics for FPRNA can be obtained with a digital gamma camera, and that accurate and reproducible measurements of global and regional left ventricular function can be obtained with this technique.     

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.     

Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies

A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.     

Cardiac pool scintigraphy using the solid-state Digirad 2020tc Imager--comparison with the conventional anger-type gamma camera using moving cardiac phantom

Movable gamma camera, 2020tc Imager, was light miniaturized using Si photodiode as a semiconductor sensor instead of photomultiplier tubes. To validate performance of this new camera in cardiac pool scintigraphy, multigated equilibrium radionuclide ventriculography using the moving cardiac phantom was performed with 2020tc Imager and a conventional Agner-type gamma camera (PRISM 3000). METHOD: Both measured cardiac functional values were compared with the set-up ones for the phantom. Five-, 7.5-, and 10-minute-multigated data were acquired using both cameras under constant contractile condition. Constant 5-minute-multigated data acquisitions using 2020tc Imager were also carried out with varied contractile conditions. RESULTS: Measured ejection fraction (EF) derived from 2020tc Imager and an Anger-type camera were 68.5 +/- 0.6 and 70.3 +/- 1.4%, respectively. Both of these values were absolutely close to the set-up EF value of 70%. Both of end-diastolic volume and EF showed excellent correlation between set-up and measured values with the correlation coefficient of 0.97 and 0.99, respectively. CONCLUSION: This new movable camera could provide comparative cardiac functional values with an Anger-type camera and it can be useful to evaluate acute cardiac function in a coronary care unit.     

Thoracic tissue thickness measured by transmission scintigraphy with 99Tcm

A flood source containing 25 mCi of technetium-99m (99Tcm) was used to measure thoracic tissue thickness (Tt) in 20 healthy subjects, 14 patients with cardiogenic pulmonary oedema, 8 patients with biopsy proven cryptogenic fibrosing alveolitis (CFA) and 10 subjects with radiographic evidence of severe, widespread emphysema. Unattenuated counts from the flood source were acquired first, and then with the subject seated between the flood source and the gamma camera, a second scan of transmitted counts was acquired. Assuming a constant linear attenuation coefficient of 0.135 cm-1, we calculated Tt per pixel of the gamma camera image, thus creating a profile of Tt throughout the length of the thorax. In normal subjects mean (S.D.) Tt at the base of the right lung was 10.8 (2.4) cm. In patients with pulmonary oedema, CFA and emphysema, mean (S.D.) values for Tt, in cm, were 12.9 (2.7) p less than 0.05, 14.4 (1.9) p less than 0.001 and 6.0 (1.1) p less than 0.0001 respectively. This simple, quick and inexpensive technique could be used to give regional measurements of Tt.     

Quantification of extracorporeal platelet deposition in cardiopulmonary bypass: effects of ZK 36374, a prostacyclin analogue

The degree of extracorporeal platelet sequestration in 32 patients undergoing cardiopulmonary bypass has been assessed using 111In labelled platelets and both a shadow shield whole body monitor and a standard gamma camera. The effects of ZK 36374, a prostacyclin analogue, on deposition of platelets in the oxygenator and atrial line filter were also investigated. Total platelet deposition in the placebo group ranged from 2.2% to 31.7%, mean 13.9 +/- 7.8%; n = 15, and was significantly higher than the deposition in the treatment group, range 0.7% to 9.4%, mean 3.9 +/- 2.6%; n = 16, P less than 0.001. There was also a highly significant correlation between the gamma camera and whole body monitor measurements, r = 0.99, P less than 0.001, with no systematic difference between the techniques. This study demonstrates that accurate quantitative assessment of platelet deposition can be achieved with either the gamma camera or whole body monitor. In addition, significant reduction in platelet sequestration in the extracorporeal circuit can be achieved by using ZK 36374 during the bypass operation.     

Application of different counting systems in measuring localised retention the entero-hepatic circulation

The use of labelled bile salt retention is likely to be a major new technique in assessing the function of the terminal ileum. Papers to date have described two techniques to measure both the 100% and the seven-day retention values. These use whole body counters or uncollimated gamma cameras. We have compared the use of simple probe systems with an uncollimated gamma camera for the retention measurements. There was no significant difference in the results obtained with any of these systems. It is concluded that simple probe measurements can provide a precise and highly reproducible assessment of bile salt retention which greatly increases the availability of this test.     

Monitoring of left ventricular ejection fraction with a miniature, nonimaging nuclear detector: Accuracy and reliability over time with special reference to blood labeling

Background

The purpose of this study was to determine the accuracy of determinations of left ventricular ejection fraction (LVEF) by a nonimaging miniature nuclear detector system (Cardioscint) and to evaluate the feasibility of long-term LVEF monitoring in patients admitted to the coronary care unit, with special reference to the blood-labeling technique.

Methods and Results

Cardioscint LVEF values were compared with measurements of LVEF by conventional gamma camera radionuclide ventriculography in 33 patients with a wide range of LVEF values. In 21 of the 33 patients, long-term monitoring was carried out for 1 to 4 hours (mean 186 minutes), with three different kits: one for in vivo and two for in vitro red blood cell labeling. The stability of the labeling was assessed by determination of the activity of blood samples taken during the first 24 hours after blood labeling. The agreement between Cardioscint LVEF and gamma camera LVEF was good with automatic background correction (r=0.82; regression equation y=1.04x+3.88) but poor with manual background correction (r=0.50; y=0.88x?0.55). The agreement was highest in patients without wall motion abnormalities. The long-term monitoring showed no difference between morning and afternoon Cardioscint LVEF values. Short-lasting fluctuations in LVEFs greater than 10EF units were observed in the majority of the patients. After 24 hours, the mean reduction in the physical decay-corrected count rate of the blood samples was most pronounced for the two in vitro blood-labeling kits (57%±9% and 41%±3%) and less for the in vivo blood-labeling kit (32%±26%). This “biologic decay” had a marked influence on the Cardioscint monitoring results, demanding frequent background correction.

Conclusion

A fairly accurate estimate of LVEF cn be obtained with the nonimaging Cardioscint system, and continuous bedside LVEF monitoring can proceed for hours with little inconvenience to the patients. Instability of the red blood cell labeling during long-term monitoring necessitates frequent background correction.     

Validation of left ventricular volume measurements by gated SPECT 99mTc-labeled sestamibi imaging

Background  Previous studies have shown that gated single photon emission computed tomography (SPECT) technetium 99-labeled sestamibi imaging provides accurate and reproducible measurement of left ventricular (LV) ejection fraction (EF), wall motion, and thickening. This study examined the reliability of gated SPECT sestamibi imaging in measuring LV end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV). Methods and Results  Gated SPECT measurements were compared with an independent nongeometric method based on thermodilution SV and first-pass radionuclide angiographic EF (using a multicrystal gamma camera). Twenty-four patients aged 58±11 years underwent cardiac catheterization and coronary angiography for evaluation of chest pain syndromes. None had primary valvular disease, intracardiac shunts, or atrial fibrillation. Results  The correlation between the two methods were as follows: EDV: r=0.89, P<.001; ESV: r=.938, P<.001; SV: r=0.557, P<.001. Bland-Altman plots showed mean differences (±standard deviation [SD]) for EDV of −14.3±33.3 mL, for ESV of −0.4±23.7 mL, and for SV of −13.9±15.2 mL. The reproducibility of measuring EDV and ESV by gated SPECT was very high (r=0.99 each). Conclusion  Gated ^99mTc-labeled sestamibi SPECT provides reproducible LV volume measurements. With validation of volume measurement, gated SPECT provides comprehensive assessment of regional and global LV function. This information is important in many patient groups such as those with ischemic cardiomyopathy, concomitant coronary and valve disease, and those who have had myocardial infarction. It will also be useful to assess the incremental value of LV volumes in risk assessment. Presented in part at the 47th Annual Meeting of the American College of Cardiology, Mar. 29–Apr. 1, 1998, Atlanta, Ga. Supported by a research grant from DuPont Pharmaceutical, Billerica, Mass. Various nuclear medicine hardware and software manufacturers have an agreement with Cedars-Sinai Medical Center through which the Medical Center receives royalties based on the distribution of the quantitative gated SPECT software.     

Validation of left ventricular volume measurements by gated SPECT Tc-labeled sestamibi imaging

Background. Previous studies have shown that gated single photon emission computed tomography (SPECT) technetium 99-labeled sestamibi imaging provides accurate and reproducible measurement of left ventricular (LV) ejection fraction (EF), wall motion, and thickening. This study examined the reliability of gated SPECT sestamibi imaging in measuring LV end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV).Methods and Results. Gated SPECT measurements were compared with an independent nongeometrie method based on thermodilution SV and first-pass radionuclide angiographic EF (using a multicrystal gamma camera). Twenty-four patients aged 58 ± 11 years underwent cardiac catheterization and coronary angiography for evaluation of chest pain syndromes. None had primary valvular disease, intracardiac shunts, or atrial fibrillation.Results. The correlation between the two methods were as follows: EDV: R = 0.89, P < .001; ESV: R = .938, P < .001; SV: R = 0.577, P < .001. Bland-Altman plots showed mean differences (± standard deviation [SD]) for EDV of −14.3 ± 33.3 mL, for ESV of −0.4 ± 23.7 mL, and for SV of −13.9 ± 15.2 mL. The reproducibility of measuring EDV and ESV by gated SPECT was very high (r = 0.99 each).Conclusion. Gated ^99mTc-labeled sestamibi SPECT provides reproducible LV volume measurements. With validation of volume measurement, gated SPECT provides comprehensive assessment of regional and global LV function. This information is important in many patient groups such as those with ischemic cardiomyopathy, concomitant coronary and valve disease, and those who have had myocardial infarction. It will also be useful to assess the incremental value of LV volumes in risk assessment.     

Quantification of extracorporeal platelet deposition in cardiopulmonary bypass: Effects of ZK 36374, a prostacyclin analogue

The degree of extracorporeal platelet sequestration in 32 patients undergoing cardiopulmonary bypass has been assessed using ¹¹¹In labelled platelets and both a shadow shield whole body monitor and a standard gamma camera. The effects of ZK 36374, a prostacyclin analogue, on deposition of platelets in the oxygenator and atrial line filter were also investigated. Total platelet deposition in the placebo group ranged from 2.2% to 31.7%, mean 13.9±7.8%; n=15, and was significantly higher than the deposition in the treatment group, range 0.7% to 9.4%, mean 3.9±2.6%; n=16, P<0.001. There was also a highly significant correlation between the gamma camera and whole body monitor measurements, r=0.99, P<0.001, with no systematic difference between the techniques. This study demonstrates that accurate quantitative assessment of platelet deposition can be achieved with either the gamma camera or whole body monitor. In addition, significant reduction in platelet sequestration in the extracorporeal circuit can be achieved by using ZK 36374 during the bypass operation.     

Basic evaluation of an ambulatory ventricular function monitor with a a cadmium telluride detector

The reliability of a new ambulatory ventricular function monitor (VEST) with cadmium telluride (Cd-Te) detector was validated. No counting loss was observed under 20 kcps. In phantom study, more than 200 ml with 6 cm distance from the detector and more than 300 ml with 6-12 cm distance, underestimation of volume was observed. Ejection fraction (EF) calculated in phantom study showed close value to the true EF in 50-400 ml of end-diastolic volume. In 10 patients, 1-2 cm detector shift toward right upper, upper and left showed underestimation of EF. Good correlation of gamma camera EF (X) and VEST EF (Y) was obtained (Y = 0.96X + 3.6(%), n = 37, r = 0.93, p less than 0.001). EF change from rest values, obtained from each comparable exercise and post exercise stage by gamma camera (X) and VEST (Y), showed good correlation (Y = 0.95X + 0.8, n = 20, r = 0.85, p less than 0.001). In conclusion Cd-Te VEST was considered as a reliable EF measurement technique similar to gamma camera.     

Reproducibility and action levels for gamma camera uniformity

Deciding on the action level for gamma camera non-uniformity is difficult because the reproducibilities of quality control measurements and service adjustments are usually unknown. This work evaluated the reproducibilities of integral uniformity (IU), differential uniformity (DU) and the corrected relative standard deviation (CRSD). The latter was calculated by removing from the relative standard deviation of the pixel counts the component due to statistical fluctuations. The reproducibility of each parameter was evaluated by analysing 10 intrinsic flood acquisitions with total counts of 2, 5, 10 and 30 million. All three parameters were less reproducible at the lower count densities, but as expected IU and DU also showed higher mean values. CRSD was consistent and highly reproducible, at all count densities. At 10 million counts CRSD had a coefficient of variation (COV) of 1.3% which was a five-fold improvement over the 6.6% and 6.1% found for IU and DU, respectively. The relative sensitivity of IU, DU and CRSD was compared in monthly measurements on 10 gamma cameras over one year. No significant difference in relative sensitivity was demonstrated: a change in camera performance produced about the same percentage change in each parameter. The precision with which service engineers adjust gamma cameras was also assessed by measuring the uniformity of 10 gamma cameras immediately after service adjustment at monthly intervals over one year. Finally, general action levels were defined for IU, DU and CRSD at 7%, 5% and 2.5% respectively.     

First-pass left ventricular ejection fraction with 95mAu on a 1/4 in. crystal gamma camera

First-pass left ventricular ejection fraction was determined in 21 patients using 195mAu. The technical aspects of the application are discussed with particular reference to the thin crystal (1/4 in.) gamma camera. The use of diverse catheter types and combinations were also investigated so that optimal administration of the radionuclide could be achieved.     

Elastic surface contour detection for the measurement of ejection fraction in myocardial perfusion SPET

The aim of this study was to investigate the use of an automated three-dimensional myocardial contour detection method using elastic surfaces for the assessment of left ventricular ejection fraction (EF) from electrocardiographically (ECG) triggered myocardial perfusion single-photon emission tomography (SPET). The validity of this method was studied on the basis of both phantom measurements and patient studies. Phantom measurements were performed using an elastic phantom of the left ventricle simulating a beating heart, with a simulated EF ranging from 10% to 78%. The data from 27 patients who had undergone both ECG-triggered myocardial perfusion SPET and planar gated radionuclide ventriculography (RNV) were used to compare the EF derived from the SPET data with the automated contour detection method and the EF derived from the RNV data with standard analysis software. EF values as measured by RNV ranged from 11% to 68%. The overall accuracy of the automated contour detection method proved to be very high. In the phantom study the deviation of the measured EF from the reference values was less than 4% for all of the simulated EFs. The studies on the patient data yielded a correlation coefficient (Pearson) greater than 0.94 as compared with planar RNV. Intra- and inter-observer reproducibility was high, with correlation coefficients exceeding 0.97. It is concluded that the proposed method allows accurate, reproducible and fast measurement of the left ventricular EF on the basis of myocardial perfusion SPET.