Quantitative detection of regional left ventricular contraction abnormalities by two-dimensional echocardiography. I. Analysis of methods.
Different approaches to the quantification of regional left ventricular (LV) function from two-dimensional echocardiographic (2-D echo) images were assessed for their ability to optimize interobserver reproducibility in a heterogeneous patient population and to minimize the variability of regional function observed in a homogeneous normal population. Areas, hemiaxis and perimeter measurements were examined, as were the effect of the degree of image subdivision into halves, quadrants or octants. Each approach was also tested using both a fixed and a floating frame of reference for the definition of a regional-axis system. The area method was consistently superior to either linear method in optimizing both reproducibility and variability. Reproducibility decreased inversely with the degree of subdivision. The axis-system frame of reference had no effect on reproducibility. The floating-axis system yielded the same variability as the fixed system for short-axis sections at the mitral valve level, but slightly less variability for a papillary muscle level section. We conclude that area-based methods are superior for the evaluation of regional LV function with 2-D echo, but the degree of subdivision of the image and the frame of reference chosen do not greatly affect reproducibility or variability and should be chosen based on their performance in a well-defined clinical population.
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