High Resolution Diffusion Tensor Imaging of the Anterior Visual Pathway in Healthy Adults

Abstract

Objective: To measure diffusion tensor imaging (DTI) parameters in healthy adults and analyze the distribution characteristics and influencing factors. Methods: In this case-series study, high resolution diffusion tensor imaging was performed on the anterior visual pathway in 38 healthy adults at the physical examination center of Fuzhou General Hospital from November 2015 to May 2016 using 3.0T magnetic resonance imaging. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured on the anterior visual pathway, including the bilateral optic nerve center, midpoint of chiasma, and the midpoint of optic tract. The anterior visual pathway fiber bundle was reconstructed by diffusion tensor tracking (DTT) to observe the morphology of the anterior optic fiber bundle. Pearson correlation, independent samples t-test, and one-way analysis of variance were used to analyze the data. Results: The structure of the DTI sequence diagram of FA, FA color encoding, and ADC can distinguish the anterior visual pathway. DTT can be used to track with 3D effects the white matter fiber bundle structure of optic chiasma. The FA and ADC values of the midpoint of optic chiasma were 0.491±0.075, and 1.267±0.204×10-3/mm2. There was a significant negative correlation between FA and ADC (r=-0.642, P<0.001). FA and ADC values were independent of gender and age. Differences between FA and ADC in optic nerve, optic tract, or optic chiasma were significant (F=11.575, P<0.001; F=5.024, P<0.001). The FA value was the smallest (P<0.001) in the optic chiasma, and the ADC value was the largest at the same location (P<0.001). Conclusions: High resolution DTI parameters FA and ADC are sensitive and reliable in the anterior visual pathway of healthy adults. The high resolution DTI technique can satisfactorily display small deformations of the anterior visual pathway fiber bundle structure. Attention should be paid to the influence of different positions of the anterior visual pathway in quantitative analyses. Key words: anterior visual pathway; magnetic resonance spectroscopy; diffusion tensor imaging; diffusion tensor tracking; adults