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Updated: Jun 23, 2025
Quantification of Optic Nerve Cross Sectional Area on MRI: A Novel Protocol using Fiji Software
Published on: September 4, 2021
Optic Nerve T2 Signal Intensity and Caliber Reflect Clinical Severity in Genetic Optic Atrophy
M Aurel Nagy1, Mary E Cunnane, Amy F Juliano
1Harvard Medical School (MAN, MEC, AFJ, JLW, EDG), Boston, Massachusetts; Department of Ophthalmology (MAN), University of California San Francisco, California; Departments of Radiology (MEC, AFJ) and Ophthalmology (JLW, EDG), Massachusetts Eye and Ear, Boston, Massachusetts; Neuroradiology Division (PAC), Lenox Hill Radiology and Medical Imaging Associates, RadNet, New York, New York; Department of Ophthalmology (EDG), Boston Children's Hospital, Boston, Massachusetts; and Picower Institute for Learning and Memory (EDG), Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts.
Background:
Genetic optic atrophies comprise phenotypically heterogenous disorders of mitochondrial function. We aimed to correlate quantitative neuroimaging findings of the optic nerves in these disorders with clinical measures.
Methods:
From a retrospective database of 111 patients with bilateral optic atrophy referred for genetic testing, 15 patients diagnosed with nonglaucomatous optic atrophy of genetic origin (7 patients with pathogenic variants in OPA1 , 3 patients with Wolfram syndrome, and 5 patients with Leber hereditary optic neuropathy) who had accessible magnetic resonance (MR) images of the orbits and/or brain were analyzed. The primary outcome measures of T2 short Tau inversion recovery (STIR) signal and optic nerve caliber were quantified according to a standardized protocol, normalized to internal standards, and compared between cases and controls. Inter-rater reliability was assessed and clinical features were analyzed according to MRI features.
Results:
Compared with control patients, the 15 genetic optic atrophy patients demonstrated significantly increased T2 STIR signal (fold-change 1.6, P = 0.0016) and decreased optic nerve caliber (fold-change 0.72, P = 0.00012) after internal normalization. These metrics were reliable (inter-reader reliability correlation coefficients of 0.98 [ P = 0.00036] and 0.74 [ P = 0.0025] for normalized STIR and nerve caliber, respectively) and significantly correlated with visual acuity, cup-to-disc ratio, and visual field testing.
Conclusions:
Normalized optic nerve STIR signal and optic nerve caliber significantly correlate with visual acuity, cup-to-disc ratio, and perimetric performance in patients with genetic optic atrophy. A formalized protocol to characterize these differences on MRI may help to guide accurate and expedient diagnostic evaluation.
