Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
On head and neck MRI, optic nerve glioma is characterized by isointense to hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI.[1]
MRI
MRI is the modality of choice for pre-treatment staging on retinoblastoma.
- The MRI features of retinoblastoma include:[1]
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| MRI component
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Features
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- T1
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- intermediate signal intensity, hyperintense c.f. vitreous
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- T2
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- hypointense c.f. vitreous
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- T1 C+ (Gd)
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- The mass usually enhances relatively homogeneously when small
- Larger tumours often have areas of necrosis, rendering it heterogeneous
- Linear enhancement of the choroid beyond the margins of the tumour should raise the possibility of choroidal involvement, although inflammation may lead to similar appearance
- Enhancement of the anterior chamber need not represent tumour involvement, with hyperaemia, uveitis and iris neovascularisation all leading to asymmetric enhancement
- Careful assessment of the optic disc and optic nerve should be carried out to assess for involvement
- Extra-ocular extension through the sclera will be visible as interruption of the otherwise hypointense non-enhancing sclera by enhancing tumour
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- DWI
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- The tumour shows restricted diffusion on DWI at high b values. It exhibits low ADC values in contrast to the high intensity of the vitreous in the ADC maps
- ADC map can be used to differentiate viable and necrotic tumour
- DWI is valuable in evaluating the response to eye-preservation treatment
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References
See also
Template:Nervous tissue tumors
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