Rigid Registration of 3D Ultrasound and MRI: Comparing Two Approaches on Nine Tumor Cases
We present a new technique for registering ultrasound and magnetic resonance (MR) images in the context of neurosurgery. It involves generating a pseudo-ultrasound (pseudo-US) from a segmented MR image and uses cross-correlation as the cost function to register with ultrasound. The algorithm’s performance is compared to a state-of-the-art technique that uses a median filtered MR images to register with a Gaussian-blurred ultrasound using normalized mutual information (NMI). The two methods are tested on nine tumor cases, including both high- and low-grade gliomas.The pseudo-US method yielded significantly better alignment average than that obtained by NMI (p = 0.0009). If one case where NMI failed is excluded, the mean distance obtained by the pseudo-US approach (2.6 mm) is slightly lower than the one obtained by NMI (2.8mm), but not significantly so (p = 0.16). We conclude that the pseudo-US method is more robust for these cases.