Clinical Study of Structural and Functional Evaluation of the Visual Pathway

Overview

Sellar area tumors such as pituitary adenoma, craniopharyngioma and meningioma, etc, commonly lead to visual impairment symptoms. Patients suffer from a loss of visual acuity (VA) and visual field defects (VF) due to a local compression on the optic chiasma by the tumor. In the management of these patients, it is an important goal to evaluate their visual function throughout the treatment, so as to predict the outcome of the visual function . Since the visual pathway contains a huge complex network of both structure and function, traditional simplex evaluation of VA and VF is obviously not enough. Former studies have revealed changes in the visual network and cortex structure in neurodegenerative diseases and optic neuritis, yet the functional and structural changes caused by local tumor compression and their relation to the visual cortex activity patterns needs further research. The objective of this research is to asses the visual function in patients with sellar area tumor 1 week preoperatively (baseline),72 hours postoperatively(checking point 1) and at 3 months follow up(checkpoint 2). By using multimodal evaluation including visual resting and task state fMRI, diffusion tensor imaging (DTI), etc. The investigators aim to reveal the changes in functional connectivity (FC), amplitude of low frequency fluctuation (ALFF), regional homogeneity (REHO) ,visual cortex activity patterns and tract-based spatial statistics (TBSS).

Detailed Description: Study objective Visual pathway contains both structural and functional network. When it is impacted by neurodegenerative diseases, neuritis or direct mechanical pressure, visual impairment occurs due to damage to the pathway. Former study on Parkinson's disease (Dagmar H. Heep et al, Radiology, 2017 ) found loss of functional connectivity in posterior and paracentral brain regions, while a study on optic neuritis (Yael Backner et al, JAMA Neurology,2018) showed an increase in functional connectivity and slightly loss in optic fiber integrity. Instead of simplex resting-state fMRI，the investigators of this study aim to assess: 1. whether similar changes in functional networking occur when visual pathway is impacted by chiasma compression from tumors in sellar area (by resting-state fMRI). 2. The correlation between local chiasma compression and visual cortex activation pattern ( by visual tasking-state fMRI). 3. Changes and recovery of the white matter fiber structure in the visual pathway. ( by diffusion tensor imaging, DTI). Method Participants: 60 adult participants (18-60 years old ) will be enrolled in the department of Neurosurgery at Xiangya Hospital of Central South University. The experimental arm will consist of 30 patients with visual impairment symptoms caused by chiasma compression by sellar area tumors (Tumor Group, TG). The control arm will consist of 30 healthy controls without any nervous system disease or visual impairment (Healthy Control Group, HC, control arm). Study design: Transversal and Longitudinal, single center, comparative study is designed to evaluate functional and structural visual networking of sellar area tumor patients and healthy controls. The study involves assessment with resting-state fMRI, tasking-state fMRI and DTI. Patients of experimental arm will be evaluated by multimodal fMRI at 3 different checkpoints (baseline is 1 week preoperative ,checkpoint 1 is 72 hours postoperative ,checkpoint 2 is 3 months follow up ). Participants of control arm will be evaluated only once. Transversal comparison will be conducted between preoperative tumor patients and healthy controls, while longitudinal comparison will be within tumor group at baseline and two other different checkpoints. MRI data acquisition and analysis strategy: In this study, the MRI data is acquired by Siemens 3.0T Prisma scanner, including sequences of mprage T1 , diffusion tensor imaging, resting-state fMRI and visual stimulation task fMRI. Resting-state fMRI longitudinal data analysis includes functional connectivity (FC), amplitude of low frequency fluctuation (ALFF) and regional homogeneity (REHO) to assess visual functional networking in both group. These Data wil be analysed using a multivariate approach and independent component analysis (ICA). Visual tasking fMRI will be conducted under classic black and white "chess board" simulation on each eye. For the evaluation of structural visual network, afferent visual pathway (optic tract and radiation ), fiber tracking as well as tract-based spatial statistics (TBSS) will be analyzed within both arms at baseline,checkpoint 1 and checkpoint 2 of the experimental arm will verify changing and recovering process of the visual pathway after chiasma decompression. Primary outcomes 1. The difference in visual pathway anatomy and functional network between preoperative sellar area tumor patients and healthy controls. Tumor patients will be evaluated clinically by visual acuity (VA), visual field (VF), tumor height and chiasma thickness. 2. The verification of the correlation between patterns of chiasma compression and visual cortex activity. Revealing the difference of visual cortex activity patterns between both arms. Secondary outcomes Throughout the 3 months follow up of the experimental arm patients, observe and verify the recovery process of both functional and structural visual network after chiasma decompression and evaluate its correlation with clinical visual function outcome. Statistics 1. An analysis of two sample T test between the two groups will be performed to assess the difference of FC,REHO,ALFF and visual cortex activity pattern between resting state data and data from the visual task of TG and HC. 2. An analysis of variance (ANOVA) within TG group will be performed to assess the changes and recovery of FC, REHO, ALFF and visual cortex activity pattern via resting state data and data from the visual task's data. Correlations will be explored between multimodal fMRI parameters (both functional and structural) and clinical criteria (e.g VA,VF, tumor size, visual outcome, etc).