MR diffusion tensor imaging of optic nerve in anterior ischemic optic neuropathy at 3.0 T and correlation between diffusion tensor imaging and pattern visual evoked potential

Abstract

Objective To study the value of MR diffusion tensor imaging (MR-DTI) using a 3.0 T scanner in anterior ischemic optic neuropathy(AION). Methods A total of 26 patients suffering from unilateral subacute AION were examined using DTI and pattern visual evoked potential(P-VEP). The parameters values of optic nerves including fractional anisotropy (FA), ADC, vertical diffusivity (λ⊥), parallel diffusion (λ∥), P100 value and amplitude were obtained. Paired t-tests were used for comparing the FA, ADC, λ⊥, and λ∥ values of the two groups. Correlations of DTI parameters and P-VEP parameters were analysed by using the Pearson rank correlation analysis. Results The values of FA, ADC, λ∥, and λ⊥ in the affected nerve were 0.28±0.07, (1.43±0.20) ×10-3 mm2/s, (1.79±0.16) ×10-3 mm2/s, and (1.25±0.17) × 10-3 mm2/s respectively, and the corresponding values of unaffected nerve were 0.57±0.05, (1.04±0.17) × 10-3 mm2/s, (1.71±0.19) × 10-3 mm2/s, and (0.75±0.08) × 10-3 mm2/s respectively. Compared to unaffected contralateral nerves, the mean FA was reduced, the mean ADC, λ⊥ were increased in the affected nerves(t= -19.269, 10.537, 15.301, P 0.05). There was significant negative correlation between ADC and P-VEP amplitude in affected optic nerves (r= -0.722, P<0.01). There was moderate negative correlation between λ⊥ and P-VEP amplitude in affected optic nerves (r= -0.634, P<0.01). There was moderate correlation between FA and P-VEP amplitude (r= 0.539, P<0.01). There was no correlation between λ∥ and P-VEP amplitude. There was moderate negative correlation between FA and P-VEP P100 latency (r = -0.619, P<0.01). Conclusions DTI can sensitively detect diffusional abnormality of anterior ischemic optic neuropathy. DTI could be used as a supplemental way in the assessment of AION. Key words: Diffusion magnetic resonance imaging; Optic nerve injuries; Evoked potentials, visual