Katie Shpanskaya1, Jennifer L Quon2, Robert M Lober3, Sid Nair4, Eli Johnson1, Samuel H Cheshier5, Michael S B Edwards6, Gerald A Grant6, Kristen W Yeom4. 1. 1Stanford University School of Medicine, Stanford. 2. 2Department of Neurosurgery, Stanford University School of Medicine, Stanford, California. 3. 3Department of Neurosurgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio. 4. 4Division of Pediatric Neuroradiology, Department of Radiology, Lucile Packard Children's Hospital, Stanford University School of Medicine, Stanford, California. 5. 5Division of Pediatric Neurosurgery, Department of Neurosurgery, University of Utah, Salt Lake City, Utah; and. 6. 6Division of Pediatric Neurosurgery, Department of Neurosurgery, Lucile Packard Children's Hospital, Stanford University School of Medicine, Stanford, California.
Abstract
OBJECTIVE: While conventional imaging can readily identify ventricular enlargement in hydrocephalus, structural changes that underlie microscopic tissue injury might be more difficult to capture. MRI-based diffusion tensor imaging (DTI) uses properties of water motion to uncover changes in the tissue microenvironment. The authors hypothesized that DTI can identify alterations in optic nerve microstructure in children with hydrocephalus. METHODS: The authors retrospectively reviewed 21 children (< 18 years old) who underwent DTI before and after neurosurgical intervention for acute obstructive hydrocephalus from posterior fossa tumors. Their optic nerve quantitative DTI metrics of mean diffusivity (MD) and fractional anisotropy (FA) were compared to those of 21 age-matched healthy controls. RESULTS: Patients with hydrocephalus had increased MD and decreased FA in bilateral optic nerves, compared to controls (p < 0.001). Normalization of bilateral optic nerve MD and FA on short-term follow-up (median 1 day) after neurosurgical intervention was observed, as was near-complete recovery of MD on long-term follow-up (median 1.8 years). CONCLUSIONS: DTI was used to demonstrate reversible alterations of optic nerve microstructure in children presenting acutely with obstructive hydrocephalus. Alterations in optic nerve MD and FA returned to near-normal levels on short- and long-term follow-up, suggesting that surgical intervention can restore optic nerve tissue microstructure. This technique is a safe, noninvasive imaging tool that quantifies alterations of neural tissue, with a potential role for evaluation of pediatric hydrocephalus.
OBJECTIVE: While conventional imaging can readily identify ventricular enlargement in hydrocephalus, structural changes that underlie microscopic tissue injury might be more difficult to capture. MRI-based diffusion tensor imaging (DTI) uses properties of water motion to uncover changes in the tissue microenvironment. The authors hypothesized that DTI can identify alterations in optic nerve microstructure in children with hydrocephalus. METHODS: The authors retrospectively reviewed 21 children (< 18 years old) who underwent DTI before and after neurosurgical intervention for acute obstructive hydrocephalus from posterior fossa tumors. Their optic nerve quantitative DTI metrics of mean diffusivity (MD) and fractional anisotropy (FA) were compared to those of 21 age-matched healthy controls. RESULTS:Patients with hydrocephalus had increased MD and decreased FA in bilateral optic nerves, compared to controls (p < 0.001). Normalization of bilateral optic nerve MD and FA on short-term follow-up (median 1 day) after neurosurgical intervention was observed, as was near-complete recovery of MD on long-term follow-up (median 1.8 years). CONCLUSIONS: DTI was used to demonstrate reversible alterations of optic nerve microstructure in children presenting acutely with obstructive hydrocephalus. Alterations in optic nerve MD and FA returned to near-normal levels on short- and long-term follow-up, suggesting that surgical intervention can restore optic nerve tissue microstructure. This technique is a safe, noninvasive imaging tool that quantifies alterations of neural tissue, with a potential role for evaluation of pediatric hydrocephalus.
Entities:
Keywords:
DTI = diffusion tensor imaging; EVD = external ventricular drain; FA = fractional anisotropy; GRAPPA = generalized autocalibrating partially parallel acquisition; ICP = intracranial pressure; MD = mean diffusivity; MRI; OCT = optical coherence tomography; PF = posterior fossa; ROI = region of interest; SNR = signal-to-noise ratio; diffusion tensor imaging; fractional anisotropy; hydrocephalus; mean diffusivity; optic nerve