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Analysis of edge-tracking errors inherent in fluoroscopic images of the beating heart
J J McInerney1, P W Weldner, M D Herr
1Division of Cardiology, Milton S. Hershey Medical Center, Hershey, PA 17033.
Rationale And Objectives:
Because of the complex relationships between the dynamic three-dimensional cardiac surface shape and its projected image, errors arise with the use of two-dimensional silhouettes to measure displacements of the heart. The character and frequency of such errors are examined.
Methods:
A high-precision x-ray scatter imaging technique was used to reconstruct the three-dimensional shape of the left ventricular free wall throughout the cardiac cycle. Displacements of the three-dimensional surface were then compared with those on the two-dimensional projected silhouette. Silhouette displacement errors were determined as a function of time during the cardiac cycle and variability between hearts.
Results:
Differences between silhouette measurements and those on the cardiac surface range from 0% to 125% of peak-to-peak displacements occur, along 33% to 75% of the silhouette contours and cover 66% of the cardiac cycle.
Conclusion:
Two-dimensional silhouette displacements provide inconsistent measurements of motion patterns on the three-dimensional cardiac surface.