A NOVEL METHOD FOR VISUALISING WHITE MATTER TRACTS IN BRAIN TUMOURS WITHOUT THE USE OF DIFFUSION WEIGHTED IMAGING

Abstract AIMS Locating eloquent white matter (WM) tracts is crucial for brain tumour resection, guiding surgery and preserv- ing neurological function. Streamline tractography is the standard but has limited intraoperative utility due to long diffusion-weighted imaging (DWI) acquisition and processing times. Faster, more accessible tract segmen- tation methods are needed. We present an adaptation of “tractfinder” that does not require DWI and instead utilises standard structural imaging and pre-existing WM segmentation tools. METHODS Two adult cases are presented. A brain mask was generated using FSL’s Brain Extraction Tool, and a lesion mask was manually delineated. WM segmentation from the patient’s T1-weighted image was generated using Freesurfer, binarised, and transformed to MNI space. The same transformation was applied to the tractfinder atlas, which was deformed and combined with the Freesurfer segmentation. Full tractfinder analysis was con- ducted for comparison. RESULTS There is good visual agreement between adapted tractfinder and full tractfinder pipelines. Visualised tracts using adapted tractfinder are larger due to the absence of patient-specific DWI. The full pipeline requires orien- tational concordance between the atlas and patient-specific diffusion data, whereas the adapted pipeline only has a WM segmentation, resulting in a weaker constraint. In an adult patient with a right pre-central gyrus tumour, adapted tractfinder successfully visualised the corti- cospinal tract (CST) close to the tumour. In a second patient with a large temporal epidermoid cyst, similar CST results were found. Visualisation of the displaced arcuate fasciculus was also comparable. CONCLUSION We demonstrate a novel approach for identifying WM tracts in tumour cases without the need for DWI, util- ising freely available pre-existing tools. The novel method produces results comparable to the full tractfinder pipeline, which has been validated against streamline tractography. This modified tractfinder method can be used quickly in both pre- and intraoperative imaging pipelines, without the need for tractography expertise, to identify WM tracts and improve surgical resection.