Quantification of Corticospinal Tracts in Brainstem Surgery: Prognostic value with Diffusion Tensor Imaging at 3-T-MRI in 14 Consecutive Cases

Aims : Because of the complex and dense anatomy of the brainstem, visualization of brainstem lesions remains challenging for neuroradiologists and neurosurgeons. The purpose of our study is to investigate the utility of diffusion tensor imaging (DTI) to map and quantify the corticospinal tracts (CSTs) in patients with brainstem lesions in regard to predict clinical outcome. Methods : Fourteen consecutive patients were retrospectively analyzed. DTI was used to determine the fractional anisotropy (FA), the apparent diffusion coefficient (ADC) of the CST. The CSTs were quantified during the pre- and postoperative course and correlated to the clinical course of each patient. Results : Correlations between FA and ADC of the CST and the corresponding clinical status were found. Furthermore, in most cases DTI-tracking allowed a broad illustration of the CST and we distinctly demonstrated pre- and postoperative variations during clinical course. Conclusion : Our study confirms that quantification of CSTs with DTI is a promising tool and helps to explain associated neurological findings and may predict outcome. Furthermore, visualizing the tracts improves our understanding of the tilted brainstem anatomy when planning those cases for surgical intervention.