NCOG-50. Correlation of tract-based diffusion metrics with visuospatial function following glioma surgery

Abstract Gliomas are diffusely infiltrative tumors without clear margins. While greater extent of resection is associated with improved overall survival, it must be balanced against the risk of iatrogenic neurological deficits which may compromise quality of life. This balance between extent of resection and good neurological outcome is particularly challenging considering our incomplete understanding of functional neuroanatomy, especially concerning long-range association fibers and the consequences of disrupting their structural integrity. The study’s objective was to evaluate post-operative tractography diffusion metrics, such as fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD) and mean diffusivity (MD), from major white matter tracts, namely subdivisions of the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF) and arcuate fasciculus (AF). These results were correlated to the Visual Object and Space Perception (VOSP) neuropsychological battery to assess the dorsal (“where”) and ventral (“what”) streams of visual processing. 11 patients in a post-operative setting for glioma resection completed the VOSP battery and diffusion tensor imaging tractography was performed. Dorsal stream performance correlated with higher FA (r = 0.78, p < 0.01) and lower RD (r = -0.67, p = 0.02) in the right SLF I tract, consistent with its described role in spatial attention. Ventral stream performance correlated notably with higher FA (r = 0.62, p = 0.04) and lower AD (r = -0.62, p = 0.04) in left SLF III, and higher FA in left IFOF (r = 0.61, p = 0.05), suggesting language-related support for object recognition. These findings illustrate the importance of white matter tracts preservation in glioma surgery, especially as visuospatial deficits are significantly correlated with decreased quality of life and loss of functional independence. Diffusion metrics may also offer better assessment of microstructural integrity than conventional imaging, which could be of interest as a predictive quantitative biomarker of high-order cognitive impairment.