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Byron Lam, Ahmet Bagci, Noam Alperin; Automated quantification of globe flattening by MRI in Idiopathic Intracranial Hypertension. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3237.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the utility of an automated MRI-derived method for measuring globe flattening associated with papilledema in patients with idiopathic intracranial hypertension (IIH).
We prospectively studied 7 women with newly-diagnosed untreated IIH and 6 healthy women of similar age, gender and BMI. The diagnosis of IIH was made using the modified Dandy criteria. The mean and SD of papilledema grade (using the Frisen scale) in the 7 IIH patients were 2.0 ±0.96 with a range of 1-4. The MR images were acquired with 1.5 and 3T scanners (Symphony and Trio; Siemens, Erlangen, Germany). MRI’s were performed before the diagnostic spinal tap and at 1 week after the spinal tap. All of the patients were treated with acetazolamide after the spinal tap. The MRI exam included heavily T2 weighted 3D volumetric MRI scan covering both eye globes with 0.6 mm isotropic resolution that was used for the quantitative analysis. The automated quantitative 3D method was employed to assess MRI changes associated with papilledema and provided 2 objective measures: 1) “globe flatness measure (GFM)” depicting overall flatness of the posterior wall of the eye, and 2) “nerve protrusion measure (NPM)”- depicting degree of optic nerve protrusion.
Mean and SD values of the GFMs and NPMs in the IIH patients were 0.897±0.028, and 0.961±0.017, respectively. These measures are significantly lower compared to those found in the healthy controls (GFM 0.947±0.015, NPM 0.986±0.009) (p= 0.0001 and 0.00012, respectively). Following treatment with acetazolamide, significant improvement was found in the GFM (0.900±0.031 vs. 0.930±0.020, p=0.04). The improvement in NPM did not each statistical significance (0.961±0.020 vs. 0.976±0.002, p=0.09).
Automated MRI-derived globe flattening and optic nerve protrusion measures provide reliable and objective quantitative measures of anatomical changes associated with papilledema and increased intracranial pressure.
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