Application Of Diffusion Tensor Imaging In Visual Impairment Caused By Pituitary Adenoma

Objective:To explore the risk factors affecting the prognosis of visual function in patients with pituitary adenoma.The nerve fibers of the visual pathway of patients with pituitary adenoma were reconstructed in vivo using DTI technology,and the relationship between visual function results and the severity of microstructural damage was quantitatively analyzed using DTI parameters.The most important thing is to determine the threshold of DTI parameters for poor visual function prognosis.Methods:Twenty patients with pituitary adenoma diagnosed and treated at the First People’s Hospital of Lianyungang City from September 2017 to January 2019 were selected as the tumor experimental group.DTI examination and visual field examination were performed in 5 periods（preoperative,the first week after operation,3 months after operation,6 months and 1 year after operation）.The DTI examination was performed by the same senior imaging technician in the imaging department,and the DTI scalar acquisition and DTT fiber reconstruction were performed by two senior imaging doctors.We also set up two control groups of 10cases each,a pituitary adenoma control group without visual impairment（tumor control group）and a healthy control group.VIS（visual impairment score）scale was used to evaluate the visual function fee of the tumor experimental group,and the prognostic patients were divided into three groups based on the degree of change in visual function of the table,which were significantly improved group,partially improved group and no improvement group.Then,we analyze whether age,tumor volume,and the degree of chiasmal lift are influential factors or risk factors for visual function prognosis.We recorded the optic chiasmreconstruction status of patients in the experimental group as two states that can be reconstructed and unreconstructed（or continuous and discontinuous）,and observed the changes of optic chiasm reconstruction status after operation.Finally,we use the receiver operating characteristic curve to analyze the FA and ADC thresholds for each period of prognosis.Statistical analysis was performed using SPSS 22.0 software.P<0.05 was considered statistically significant.Results:There were no significant differences in age in the three prognostic groups,tumor volume had significant differences in the three prognostic groups,and the degree of chiasmal lift had significant differences in the three prognostic groups.The degree of visual field defect was significantly negatively correlated with the patient’s FA value（r=-0.6898,p=0.008）,and was significantly positively correlated with the patient’s ADC value（r=0.6300,p=0.0029）;tumor volume was significantly negatively correlated with the patient’s FA value（r=-0.6421,p=0.0023）,and was significantly positively correlated with the patient’s ADC value（r=0.4815,p=0.0316）;the degree of chiasmal lift was significantly negatively correlated with the patient’s FA value（r=-0.6306,p=0.0029）,but not significantly correlated with ADC values??（r=0.3018,p=0.1959）.After DTI reconstruction,the number of continuities of the patients’postoperative visual crosses increased significantly,with the highest in the first week after the operation,and the overall continuity increased from 20%before operation to 85%after operation.The comparison between the DTI parameters of the experimental group and the control group shows that the FA value is significantly different between the patient experimental group and the patient control group（P﹤0.0001）;the FA value is significantly different between the patient experimental group and the normal control group.（P﹤0.0001）;FA values??were not significantly different between the patient control group and the normal control group（P=0.4667）;ADC values??were significantly different between the patient experimental group and the patient control group（P﹤0.0001）;The ADC value was significantly different between the patient’s experimental group and the normal control group（P<0.0001）;while the ADC value was not significantly different between the patient control group and the normal control group（P=0.4579）.The thresholds of FA value and ADC value of total 5 periods were 0.353 and1.618×10^-3mm²/s（preoperative）,0.419 and 1.459×10^-3mm²/s（1 week after operation）,0.427 and 1.348×10^-3mm²/s（3 months after surgery）,0.441 and 1.317×10^-3mm²/s（6months after surgery）,0.442 and 1.298×10^-3mm²/s（1 year after surgery）.Finally,we found no significant differences in FA and ADC values??between one year and six months after surgery,and there were significant differences in previous comparisons.CONCLUSION:Age is not a factor influencing the prognosis of visual function,and tumor volume and visual cross-lift height are obvious factors influencing the prognosis of visual function.The optic nerve fibers can be well simulated and reconstructed by DTI technology.Pituitary adenoma compression causes the compressed visual pathway.After surgical intervention and contact compression,DTI parameters can be used to indirectly reflect the process of axon regeneration and remyelination.Preoperative and postoperative periods are less than FA or greater than the ADC threshold,which indicates that the possibility of poor prognosis of patients with visual function is extremely high.In patients with visual dysfunction caused by pituitary adenoma,the microscopic recovery of optic fibers after surgical intervention lasts about half a year after surgery.Basically stopped.