Reconstruction error in 3D ultrasound imaging with mechanical probes

Abstract

Three-dimensional (3D) ultrasound data are acquired mostly using a dedicated mechanical probe that houses a 1D array transducer. This 1D transducer swivels back and forth continuously in the elevation direction (continuous scanning) for fast acquisition. When 3D ultrasound data are acquired via continuous scanning but the continuous motion of a transducer is not taken into account during reconstruction, the reconstructed volume contains error. In this study, we systematically analyzed this error, which is a complex function of many parameters. The error increases when the transducer angular speed (ω) increases. Also, it varies depending on the voxel location inside an acquired volume. The mean error is calculated by averaging the errors at all acquired voxel locations. With a 60-degree volume angle, a 60-degree sector angle, 12-cm scan depth and 48 transmit beams per slice, the mean error is 5.3 mm when ω is 0.6 degrees/ms. When ω is reduced to 0.1 degrees/ms, the mean error decreases to 0.81 mm. We also assessed the impact of this error on the reconstructed images of a 3D phantom using simulation. At high angular speeds, the error in reconstructed images becomes noticeable and results in missing parts, geometric distortion and lowered image quality.