Left ventricular (LV) volumes are valuable prognostic indicators in the man
agement of coronary artery disease and traditionally have been obtained by
x-ray contrast angiography or echocardiography. There now are several scint
igraphic methods to compute volumes that are based on different LV modeling
assumptions. Both the reasons that calculations from different nuclear tec
hniques can disagree with one another and the relationship of these values
to the more conventional echocardiographic measurements must be investigate
d thoroughly for calculations to be interpretable for individual patients.
Methods: Echocardiographic volumes were determined in 33 retrospective subj
ects with coronary artery disease (mean age, 61 +/- 12 y; 42% men; 70% with
abnormal perfusion and 58% with abnormal segmental wall motion) using the
modified Simpson's rule technique applied to digitized apical 4-chamber and
apical P-chamber views of 4 averaged heartbeats. These volumes were compar
ed with those from 3 gated SPECT methods based on Simpson's rule LV modelin
g similar to standard echocardiographic algorithms (SPECT EF from St. Luke'
s-Roosevelt Hospital) (method 1), Gaussian myocardial count profile curve f
itting (QGS from Cedars-Sinai Medical Center) (method 2), and an endocardia
l model based on perfusion sampling and count-based thickening (Cardiac Too
lbox from Emery University) (method 3). Results: By ANOVA, there were no si
gnificant differences among ejection fractions (EFs), but there were for vo
lumes. Paired t test analysis showed volumes from methods 2 and 3 to be sig
nificantly larger than echocardiographic volumes and larger than those of m
ethod 1. Linear regression analysis comparing gated SPECT and echocardiogra
phic volumes showed a nearly identical strong correlation (r = 0.92; P < 0.
000001) for all 3 methods. Excellent correlation also was found among gated
SPECT volumes from the 3 methods (r = 0.94), Bland-Altman analysis and t t
ests showed that method I volumes (70 +/- 61 mt) were the same as for echoc
ardiography (77 +/- 55 mL), but volumes were overestimated by method 2 (105
+/- 74 mt) and method 3 (127 +/- 92 mi), particularly for larger volumes.
Pearson coefficients for EFs compared with echocardiography were r = 0.82,
0.75, and 0.72 for methods 1-3, respectively. EFs correlated strongly among
the 3 gated SPECT methods (r = 0.86-0.92). The Fisher z test showed no dif
ferences among these methods for any of the volume or EF linear correlation
analyses. Conclusion: All gated SPECT parameters correlated well with echo
cardiographic values. However, the gated SPECT method for which underlying
assumptions most closely resembled those commonly used in echocardiography
produced mean volume Values closest in agreement with echocardiographic mea
surements.