Investigation of nerve fibre imaging in radiosurgery

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20-40% of all cancer patients develop brain metastases (BM). The incidence is likely to increase as cancer patients are living longer. Effective treatment provides patients with a high quality of life, but must be efficient and accurate due to increasing patient numbers and the risks associated with treatment failure. An increasingly used precise treatment is "stereotactic brain radiosurgery" (SRS), which avoids sensitive brain regions and can be used repeatedly if new metastases are later diagnosed, which happens in more than 50% of cases. As in neurosurgery (NS), SRS relies on magnetic resonance imaging (MRI) for planning treatment. In NS, MRI provides the neurosurgeon with the optimal approach through the brain, avoiding important brain structures. In SRS, MRI provides the optimal path of the radiation beams. There is increasing interest in obtaining brain nerve fiber maps using an MRI technique called "diffusion tensor imaging" (DTI) for NS planning. DTI could also be used in SRS planning to minimize injury to important neural pathways and nerves, especially when patients have had previous SRS. Furthermore, DTI may improve detection of radiation damage to nerve fibers, and better delineate tumour boundary than with current imaging. However, DTI is very sensitive to spatial distortions, which currently limits its utility. Synaptive Medical is a medical device/software company based in Toronto that has developed solutions for correcting and incorporating fiber tract visualization into NS planning (BrightMatterTM Plan), as well assessing incoming DTI scans for meeting minimum diagnostic requirements (BrightMatterTM Bridge). The main proposal objective is to investigate how Synaptive's solutions may improve SRS planning accuracy. Project milestones include evaluation of: currently used DTI protocols, functionality needed for SRS planning, ability to see BM boundary, and ability to visualize nerve fiber damage from SRS.