Vitreous humor diffusion measurements from diffusionweighted imaging in idiopathic intracranial hypertension.

Background and purpose: Idiopathic intracranial hypertension is a disease with uncertain etiology. It is not caused by an intracranial mass lesion or hydrocephalus and is characterized by abnormal elevation of intracranial pressure and normal composition of the cerebrospinal fluid. The orbita and intracranial area are closely related anatomically. Elevated intracranial pressure can be transmitted to the orbita through the cerebrospinal fluid around the optic nerve sheath changes at the vitreous humor on diffusion-weighted imaging have not been systemically studied in idiopathic intracranial hypertension. Purpose - The purpose of this study was to investigate diffusion changes in the vitreous humor in patients with intracranial hypertension.

Methods: In this retrospective study, 25 patients with papilledema and who had been definitively diagnosed with idiopathic intracranial hypertension and 20 control participants were evaluated. Control subjects and patients were scanned with a 1.5 Tesla magnetic resonance imaging. Apparent diffusion coefficient maps were obtained from diffusion-weighted imaging with a b value of 1000 s/mm2 and apparent diffusion coefficient values were automatically calculated. These images were obtained by a radiologist who was blinded to the details of the study for center of each vitreous humor and the body of lateral ventricle. The mean apparent diffusion coefficient values of each vitreous humor and the body of the lateral ventricle were calculated for each group (control group and patients) and quantitative comparisons were performed.

Results: There were no statistically significant differences in mean apparent diffusion coefficient values of the right vitreous humor, left vitreous humor and the body of the lateral ventricle between the patients with idiopathic intracranial hypertension and the control group (p=0.766, p=0.864, p=0.576, respectively).

Conclusion: Vitreous humor is a closed system and has no direct relationship with the cerebrospinal fluid or cerebral tissue and although morphological changes occur in the orbital structures, including the optic disk and optic nerve in idiopathic intracranial hypertension, the indirect effects of these changes on the vitreous humor may be too subtle to measure. Conclusion - We did not find a significant difference in the mean apparent diffusion coefficient value of the vitreous humor between the patients with idiopathic intracranial hypertension and the control group. However, future studies will be necessary to determine if changes in the vitreous humor can be used to diagnose intracranial hypertension.