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T2‐WEIGHTED MAGNETIC RESONANCE IMAGING MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER IN DOGS WITH AND WITHOUT PRESUMED INTRACRANIAL HYPERTENSION
Author(s) -
Scrivani Peter V.,
Fletcher Daniel J.,
Cooley Stacy D.,
Rosenblatt Alana J.,
Erb Hollis N.
Publication year - 2013
Publication title -
veterinary radiology and ultrasound
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.541
H-Index - 60
eISSN - 1740-8261
pISSN - 1058-8183
DOI - 10.1111/vru.12023
Subject(s) - medicine , optic nerve , magnetic resonance imaging , nerve sheath , nuclear medicine , ophthalmology , radiology , schwannoma
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 T 2‐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.