Can Preoperative Diffusion Tensor Imaging Tractography Predict the Visual Outcomes of Patients with Pituitary Macroadenomas? A Prospective Pilot Study

-OBJECTIVE: Visual impairment has been reported as the most common clinical manifestation of pituitary adenoma (PA) due to the compressive effect of the tumor. This pro-spective study aimed to evaluate the predictive role of diffusion tensor imaging (DTI) in the visual improvement of patients with PA, who were candidates for endoscopic endonasal surgery.-METHODS: A total of 13 patients (male, 8; female, 5) with visual impairment due to pituitary macroadenoma were enrolled in this study. The DTI findings and visual param-eters, including visual acuity (VA), visual field (VF), and visual evoked potential (VEP), were recorded for all par-ticipants before and 3 months after surgery.-RESULTS: Significant recovery was reported in both VA and VF following PA surgery (P < 0.001). The results of perimetry indicated recovery in all quadrants, except for the lower nasal quadrant of the right eye. The tumor volume showed no significant association with the preoperative optic nerve, optic tract, and chiasm fractional anisotropy (FA) or mean diffusivity (MD). The VA and VF recoveries were more likely in patients with a lower preoperative optic nerve MD. Besides, increased preoperative FA of the optic nerve was associated with a higher probability of VA recovery. No significant correlation was found between the optic tract MD and FA values and visual improvement. Overall, MD values below 0.0021 and FA values above 0.1689 could predict a good prognosis of VA recovery after surgery.-CONCLUSIONS: DTI may have a predictive value in estimating visual improvement in patients with PA preoperatively.