title: Hyperintense Optic Nerve due to Diffusion Restriction: Diffusion-Weighted Imaging in Traumatic Optic Neuropathy.
abstract: OBJECTIVE
  Abnormal signal intensity of the optic nerve due to diffusion restriction may be seen in traumatic optic neuropathy. In addition to evaluating optic nerve hyperintensity on diffusion-weighted imaging, we compared the group differences of ADC values between the injured and uninjured contralateral nerve and identified the relation between measured ADC values and admission visual acuity.
  
  
  METHODS
  We retrospectively evaluated 29 patients with traumatic optic neuropathy who underwent MR imaging with DWI. Uninjured contralateral optic nerves were used as controls. Two attending radiologists, blinded to the side of injury, independently reviewed the DWI for the presence of signal-intensity abnormality and obtained ADC values after manually selecting the ROI.
  
  
  RESULTS
  Hyperintensity of the optic nerve was demonstrated in 8 of the 29 patients, with a sensitivity of 27.6% (95% CI, 12.8-47.2) and a specificity of 100% (95% CI, 87.9-100). ADC values were obtained in 25 patients. The mean ADC in the posterior segment of the injured nerve was significantly lower than that in the contralateral uninjured nerve (Welch ANOVA, F = 9.7, P = .003). There was a moderate-to-strong correlation between low ADC values and poor visual acuity in 10 patients in whom visual acuity could be obtained at admission (R = 0.7, P = .02). Patients with optic nerve hyperintensity presented with worse visual acuity.
  
  
  CONCLUSIONS
  Hyperintensity of the optic nerve due to diffusion restriction can serve as a specific imaging marker of traumatic optic neuropathy. When paired with reduced ADC values, this finding may be an important surrogate for visual acuity.
authors.affiliation: From the Departments of Radiology, R Adams Cowley Shock Trauma Center (U.K.B., K.S., D.D.) ubodanapally@umm.edu.
authors.forename: U K
authors.initials: UK
authors.lastname: Bodanapally
authors.affiliation: From the Departments of Radiology, R Adams Cowley Shock Trauma Center (U.K.B., K.S., D.D.).
authors.forename: K
authors.initials: K
authors.lastname: Shanmuganathan
authors.affiliation: Ophthalmology and Visual Sciences (R.K.S., L.K.), University of Maryland Medical Center, Baltimore, Maryland.
authors.forename: R K
authors.initials: RK
authors.lastname: Shin
authors.affiliation: From the Departments of Radiology, R Adams Cowley Shock Trauma Center (U.K.B., K.S., D.D.).
authors.forename: D
authors.initials: D
authors.lastname: Dreizin
authors.affiliation: Ophthalmology and Visual Sciences (R.K.S., L.K.), University of Maryland Medical Center, Baltimore, Maryland.
authors.forename: L
authors.initials: L
authors.lastname: Katzman
authors.affiliation: Albert Einstein College of Medicine of Yeshiva University (R.P.R.), Bronx, New York.
authors.forename: R P
authors.initials: RP
authors.lastname: Reddy
authors.affiliation: University of Maryland School of Medicine (D.M.), Baltimore, Maryland.
authors.forename: D
authors.initials: D
authors.lastname: Mascarenhas
mesh_terms: D000293:Adolescent; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D020221:Optic Nerve Injuries / Q000473:pathology*; D012189:Retrospective Studies