The lateral subventricular zone has been explored in association with high-grade gliomas, both in-vivo and with MRI. The third ventricle subventricular zone (TVZ) has been explored in-vivo, using immunohistochemistry and microarray analysis, with regard to neurofibromatosis type-1-associated low-grade optic pathway gliomas. This remains unexplored with MRI. This study examined diffusion MRI features of the TVZ and its association with NF1-status and peri-tumour white matter integrity. TVZ features correlated with NF1-status, and peri-tumour white matter integrity. These results suggest that the state of the TVZ environment can potentially indicate whether a sporadic tumour might behave like its less disruptive NF1-associated counterpart.