Intra-operative brain shift correction with weighted locally linear correlations of 3DUS and MRI

Abstract

During brain tumor resection procedures, 3D ultrasound (US) can be used to assess brain shift, as intra-operative MRI is challenging due to immobilization issues, and may require sedation. Brain shift can cause uncertainty in the localization of resected tumor margins and deviate the registered pre-operative MRI surgical plan. Hence, 3D US can be used to compensate for the deformation. The objective of this study is to propose an approach to automatically register the patient’s MRI to intra-operative 3D US using a deformable registration approach based on a weighted adaptation of the locally linear correlation metric for US-MRI fusion, adapting both hyper-echoic and hypo-echoic regions within the cortex. Evaluation was performed on a cohort of 23 patients, where 3D US and MRI were acquired on the same day. The proposed approach demonstrates a statistically significant improvement of internal landmark localization made by expert radiologists, with a mean target registration error (mTRE) of 4.6 ± 3.4 mm, compared to an initial mTRE of 5.3 ± 4.2 mm, demonstrating the clinical benefit of this tool to correct for brain shift using 3D ultrasound.