T2-WEIGHTED MAGNETIC RESONANCE IMAGING MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER IN DOGS WITH AND WITHOUT PRESUMED INTRACRANIAL HYPERTENSION

Authors

  • Peter V. Scrivani,

    Corresponding author
    • From the Department of Clinical Sciences, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Daniel J. Fletcher,

    1. From the Department of Clinical Sciences, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Stacy D. Cooley,

    1. From the Department of Clinical Sciences, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Alana J. Rosenblatt,

    1. From the Department of Clinical Sciences, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Hollis N. Erb

    1. From the Department of Clinical Sciences, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • None of the authors of this paper has a financial or personal relationship with other people or organizations that could inappropriately influence or bias the content of this paper.

Address correspondence and reprint requests to Peter V. Scrivani, DVM, at the above address. E-mail: pvs2@cornell.edu

Abstract

Intracranial hypertension is a cause of cerebral ischemia and neurologic deficits in dogs. Goals of this retrospective study were to test interobserver agreement for MRI measurements of optic nerve sheath diameter and associations between optic nerve sheath diameter, signalment data, and presumed intracranial hypertension status in a cohort of dogs. A veterinary radiologist interpreted scans of 100 dogs and dogs were assigned to groups based on presence or absence of at least two MRI characteristics of presumed intracranial hypertension. Two observers who were unaware of group status independently measured optic nerve diameter from transverse T2-weighted sequences. Mean optic nerve sheath diameter for all dogs was 3 mm (1–4 mm). The mean difference between observers was 0.3 mm (limits of agreement, −0.4 and 1.0 mm). There was no correlation between optic nerve sheath diameter and age for either observer (r = −0.06 to 0.00) but a moderate positive correlation was observed between optic nerve sheath diameter and body weight for both observers (r = 0.70–0.76). The 22 dogs with presumed intracranial hypertension weighed less than the 78 dogs without (P = 0.02) and were more often female (P = 0.04). Dogs with presumed intracranial hypertension had a larger ratio of optic nerve sheath diameter to body weight for each observer-side pair (P = 0.01–0.04) than dogs without. Findings indicated that the ratio of MRI optic nerve sheath diameter relative to body weight may be a repeatable predictor of intracranial hypertension in dogs.

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