Background. Cardiac gated blood pool single photon emission computed tomography (GBPS) better separates cardiac chambers compared with planar radionuclide ventriculography (PRNV). We have developed a completely automatic algorithm to measure quantitatively the left ventricular ejection fraction (LVEF) from gated technetium 99m-red blood cells (RBC) GBPS short-axis 3-dimensional image volumes.Methods and Results. The algorithm determines an ellipsoidal coordinate system for the left ventricle and then computes a static estimate of the endocardial surface by use of counts and count gradients. A dynamic surface representing the endocardium is computed for each interval of the cardiac cycle by use of additional information from the temporal Fourier transform of the image data sets. The algorithm then calculates the left ventricular volume for each interval and computes LVEF from the end-diastolic and end-systolic volumes. The algorithm was developed in a pilot group (N = 45) and validated in a second group (N = 89) of patients who underwent PRNV and 8-interval GBPS. Technically inadequate studies (N = 38) were rejected before grouping and processing. Automatic identification and contouring of the left ventricle was successful in patients (70%) globally and in patients (85%) in the validation group. Correlation between LVEFs measured from GBPS and PRNV was high (y = 2.00 + 1.01x, r = 0.89), with GBPS LVEF significantly higher than PRNV LVEF (average difference = 2.8%, P < .004).Conclusions. Our automatic algorithm agrees with conventional radionuclide measurements of LVEF and provides the basis for 3-dimensional analysis of wall motion.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to develop and validate a new algorithm to automatically compute left ventricular ejection fraction (LVEF) from gated blood-pool tomography (GBPT). The results were compared with those of conventional planar radionuclide angiocardiography (PRNA).
Fifty-three consecutive patients received an injection of 740 MBq (99m)Tc-labeled human serum albumin. PRNA and GBPT were performed consecutively in a random sequence. PRNA served as the reference, and GBPT images were processed using a new edge detection algorithm. The algorithm is fast (<45 s), fully automatic, and works in three-dimensional space. The method includes identification of the valve plane and the septum. The left ventricular cavity at end-diastole is delineated by segmentation using an iterative threshold technique. An optimal threshold is reached when the corresponding isocontour best fits the first derivative of the end-diastolic count distribution in three dimensions. This optimal threshold is then applied to delineate the left ventricular cavity on the other time bins. The data are corrected for the partial-volume effect. Left ventricular volumes are determined using a geometry-based method and are used to calculate the ejection fraction.
The success rate of the new algorithm was 94%. LVEFs calculated from GBPT agreed well with those calculated from PRNA (r = 0.78; GBPT = 0.94 PRNA + 6.33). The systematic error was 2.8%, and the random error was 8.8%. Excellent inter- and intraobserver reproducibility was found, with average differences of 1.1% +/- 4.6% and 1.1% +/- 5.0%, respectively, between the two measurements.
This new algorithm provides a fast, automated, and objective method to calculate LVEF from GBPT.
Journal of Nuclear Medicine 04/2001; 42(3):401-7. · 6.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this preliminary study was to evaluate the accuracy of left and right ventricular output computed from a semi-automatic processing of tomographic radionuclide ventriculography data (TRVG) in comparison with the conventional thermodilution method. Twenty patients with various heart diseases were prospectively included in the study. Thermodilution and TRVG acquisitions were carried out on the same day for all patients. Analysis of gated blood pool slices was performed using a watershed-based segmentation algorithm. Right and left ventricular output measured by TRVG correlated well with the measurements obtained with thermodilution (r = 0.94 and 0.91 with SEE = 0.38 and 0.46 l/min, respectively, P < 0.001). The limits of agreement for TRVG and thermodilution measurements were -0.78-1.20 l/min for the left ventricle and -0.34-1.16 l/min for the right ventricle. No significant difference was found between the results of TRVG and thermodilution with respect to left ventricular output (P = 0.09). A small but significant difference was found between right ventricular output measured by TRVG and both left ventricular output measured by TRVG (mean difference = 0.17 l/min, P = 0.04) and thermodilution-derived cardiac output (mean difference = 0.41 l/min, P = 0.0001). It is concluded that the watershed-based semi-automatic segmentation of TRVG slices provides non-invasive measurements of right and left ventricular output and stroke volumes at equilibrium, in routine clinical settings. Further studies are necessary to check whether the accuracy of these measurements is good enough to permit correct assessment of intracardiac shunts.
European Journal of Nuclear Medicine 05/2001; 28(4):506-13. DOI:10.1007/s002590100497 · 5.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
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.
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.
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