International Journal of Ophthalmology (Aug 2019)

Assessment of optic nerve and optic tract alterations in patients with orbital space-occupying lesions using probabilistic diffusion tractography

  • Chun-Nan Wu,
  • Shao-Feng Duan,
  • Xue-Tao Mu,
  • Yi Wang,
  • Peng-Yu Lan,
  • Xiao-Lu Wang,
  • Kun-Cheng Li

DOI
https://doi.org/10.18240/ijo.2019.08.11
Journal volume & issue
Vol. 12, no. 8
pp. 1304 – 1310

Abstract

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AIM: To investigate the diffusion changes in both the optic nerve and optic tract in orbital space-occupying lesion patients with decreased visual acuity, and its clinical significance using probabilistic diffusion tractography (PDT). METHODS: Twenty patients with orbital space-occupying lesions and 25 age- and gender-matched healthy persons were included. All patients and controls underwent routine orbital magnetic resonance imaging and diffusion tensor imaging (DTI), using a 3.0T magnetic resonance scanner (Trio Tim Siemens). After the image data were preprocessed, each DTI parameters of the optic nerve and optic tract was obtained by PDT, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). The asymmetry index (AI) of each parameter was calculated. Compared the parameters of the affected side optic nerve and ipsilateral optic tract with the contralateral side by paired sample t-test; compared AI of parameters of optic nerve and optic tract between the patient group and the control group by independent sample t-test. Patients were divided into three subgroups according to the low vision grade standard of WHO, compared the FA and AI of FA between the three subgroups by single factor variance analysis. RESULTS: The affected side optic nerve presented significantly decreased FA, increased MD, AD, and RD values compared to the unaffected side (P0.05). The AIs of the FA value of the optic nerve in the eyesight <0.1 subgroup was significantly higher than that in the other groups (P<0.05). CONCLUSION: FA, MD, AD, and RD of the affected side optic nerve of the orbital space-occupying lesions have significantly changed, the FA value is the most sensitive. The PDT could be a useful tool to provide valid quantitative markers of optic nerve injuries and evaluate the severity of orbital diseases, which other examinations cannot be acquired.

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