Head-to-head comparison of two-dimensional and three-dimensional echocardiographic methods for left atrial chamber quantification with magnetic resonance imaging

Background: Limited data are available on the accuracy of quantification methods for left atrial (LA) volumes using two-dimensional (2D) and particularly real-time three-dimensional echocardiographic (RT3DE) methods in comparison with a reference standard. The aim of this study was to perform a head-to-head comparison between 2D and RT3DE methods with magnetic resonance imaging (MRI) as the reference standard.

Methods: LA volumes derived from 2D echocardiographic methods (i.e., biplane modified Simpson's, biplane area-length, and prolate ellipse methods) and from RT3DE methods (i.e., 4D LA Analysis and QLAB) in 60 consecutive patients were compared with MRI measurements. Offline analysis time was recorded.

Results: The biplane modified Simpson's and area-length methods showed good intraclass correlations with MRI for maximum (r = 0.70 and r = 0.69, P < .001) and minimum (r = 0.83 and r = 0.82, P < .001) volumes. Although RT3DE methods led to moderate increases in correlations for maximum (r = 0.94 and 0.70, P < .001) and minimum (r = 0.95 and r = 0.90, P < .001) volumes and narrower Bland-Altman limits of agreement than 2D echocardiographic methods, offline analysis time was higher for RT3DE (155-161 vs 103-144 sec). Compared with MRI, maximum and minimum LA volumes were underestimated by -4.7% and -8.9%, respectively, using 4D LA Analysis, by -15.7% and -14.9% using QLAB, by -12.3% and -4.4% using the biplane Simpson's method, by -13.7% and -6.8% using the area-length method, and by -48.2% and -50.5% using the prolate ellipse method.

Conclusions: The biplane Simpson's and area-length methods offer reasonable accuracy for LA chamber quantification across a broad range of volumes, while RT3DE methods lead to a moderate improvement in accuracy at the cost of more elaborate offline analysis.