Abstract
AIM: To demonstrate the imaging findings of nonarteritic anterior ischemic optic neuropathy (NAION) using high-resolution magnetic resonance imaging (MRI) sequences. METHODS: A retrospective review of 4y of medical records and MRIs of nine patients suspected of having NAION who underwent orbit protocol MRI was conducted. The orbit MRI protocol included high-resolution three-dimensional (3D) T2-weighted imaging (HR 3D T2WI), high-resolution 3D contrast-enhanced T1-weighted imaging (HR-CE 3D T1WI), and high-resolution 3D T2-fluid-attenuated inversion recovery imaging (HR-CE 3D T2-FLAIR) and diffusion-weighted imaging, if applicable. To rule out other causes of optic neuropathy such as inflammatory optic neuritis, we evaluated the presence of optic disc swelling, contrast enhancement at the optic disc, and other abnormal findings on these sequences. RESULTS: Among the 715 patients, 9 were diagnosed with NAION. The median age of the patients was 62y (range, 46-79y), and five patients (56%) were men. Two of these patients demonstrated optic disc swelling on HR 3D T2WI and focal contrast enhancement on HR-CE 3D T1WI. Eight patients showed focal contrast enhancement on HR-CE 3D T2-FLAIR imaging. Among these patients, five showed a focal contrast enhancement only on HR-CE 3D T2-FLAIR imaging. The most frequent location of the focal contrast enhancement was the superomedial (n=5, 56%) followed by the medial (n=2, 22%) and central (n=2, 22%), and superior (n=1) aspects. In all three patients for whom diffusion-weighted imaging was available, there was no evidence of diffusion restriction in the optic disc. CONCLUSION: This study demonstrates the imaging finding of NAION using high-resolution MRI sequences. HR-CE T2-FLAIR imaging is particularly useful in detecting NAION when combined with other high-resolution MRI sequences. It can provide additional insights into the pathophysiology of NAION, which may aid in obtaining an appropriate diagnosis and follow-up.