Combined use of tractography and gamma knife radiosurgery three dimensional treatment planning: initial experience

Object: The goal of this study was to assess the feasibility of fusion between diffusion-tensor imaging (DTI), based tractography and pre-radiosurgery stereotactic Magnetic Resonance Imaging (MRI), to evaluate irradiation to eloquent tissue surrounding treated lesions. Materials and methods: Eight patients with brain arterio-venous malformation or brain tumor were studied at 3 T to obtain DTI and at 1 T to obtain stereotactic three-dimensional imaging. Fiber tracking of the corticospinal tract (CST) was performed bilaterally in each patient. Finally image registration between 3D corticospinal tractography and 3D T1-weighted stereotactic volumetric study was performed. To verify the accuracy of the registration process the position of the CST at the level of the posterior limb of the internal capsule and of cerebral peduncle was specifically assessed. Results: Image registration was feasible in all patients and was performed within 15 min. Location of the CST within the posterior limb of the internal capsule and the cerebral peduncle corresponded to previous reports. Conclusion: Integration of tractography, within gamma knife surgery stereotactic imaging planning, is feasible and compatible within a routine clinical setting. Data obtained with this technique may be used to obtain a better estimate of the maximum radiation dose delivered to specific tracts.