The purpose of the study was to examine the brain and the visual pathway of patients with non-arteritic anterior ischaemic
optic neuropathy (NAION) by using conventional MRI (cMRI) and volumetric magnetisation transfer imaging (MTI). Thirty NAION
patients, aged 67.5 ± 8.14 years, and 28 age- and gender-matched controls were studied. MTI was used to measure the magnetisation
transfer ratio (MTR) of the chiasm and for MTR histograms of the brain. The presence of areas of white matter hyperintensity
(WMH) was evaluated on fluid-attenuated inversion recovery (FLAIR) images. Area of the optic nerves (ONs) and volume of the
chiasm were assessed, as were coronal short-tau inversion recovery (STIR) and MTI images, respectively. More areas of WMH
were observed in patients (total 419; mean 14.4; SD 19) than in controls (total 127; mean 4.7; SD 5.7),
P < 0.001. Area (in square millimetres) of the affected ONs, volume(in cubic millimetres) and MTR (in percent) of the chiasm
(10.7 ± 4.6), (75.8 ± 20.2), (56.4 ± 6.5), respectively, were lower in patients than in controls (13.6 ± 4.3), (158.2 ± 75.3)
(62.1 ± 6.2), respectively,
P < 0.05. Mean MTR of brain histograms was lower in patients (53.0 ± 8.0) than in controls (58.0 ± 5.6),
P < 0.05. NAION is characterised by decreased ON and chiasmatic size. The low MTR of the chiasm and brain associated with increased
areas of WMH may be suggestive of demyelination and axonal damage due to generalised cerebral vascular disease.
Keywords Magnetic resonance imaging - Non-arteritic anterior ischaemic optic neuropathy - Visual pathway - Magnetisation transfer ratio