Fang S, et al. - The relationship between the anatomic location of a tumor and the accuracy of fMRI-based motor function mapping in diffuse lower-grade gliomas is evaluated in this study. This examination recommends that the shortest distance from the tumor to the hand knob and the deviation distance for the midpoint of the hand knob on the lesion hemisphere are predictive of the accuracy of blood oxygen level-dependent fMRI results. Smaller shortest distances from the tumor to the hand knob and larger deviation distances for the midpoint of hand knob on the lesion hemisphere are related to less accuracy of motor cortex localization with blood oxygen level-dependent fMRI. Preoperative fMRI data for surgical planning ought to be utilized cautiously when the shortest distance from the tumor to the hand knob is ≤ 4 mm, particularly for lower-grade gliomas anterior to the central sulcus.