Investigation into the fusion of multiple 4-D fetal echocardiography images to improve image quality.

Recent advances in four-dimensional (4-D) ultrasound enable the acquisition and visualisation of the entire fetal heart. However, getting consistent, shadow free, data remains problematic due to the uncontrollable nature of fetal orientation. This article presents the first investigation into the utility of image fusion to improve the quality of volumetric fetal cardiac imaging. Multiple volume scans are registered using a semiautomatic approach and five fusion methods are assessed for their ability to remove artefacts and improve image quality. Image quality is assessed in terms of signal-to-noise ratio, contrast and contrast-to-noise ratio. Qualitative results are presented for the ability to remove artefacts. The fusion methods assessed were found to be divided into those that reduce noise and those that increase contrast. The effect of fusion on left ventricle segmentation using commercial state-of-the-art software is also considered. The use of image fusion is shown to reduce the variability of volume estimates by about 50% relative to measurement on a single scan.