Abstract
Purpose: :
The diagnosis of Idiopathic Intracranial Hypertension (IIH) is one of exclusion, requiring normal neuroimaging and imaging the dural venous sinuses is challenging. Cerebral venous sinus thrombosis (CVST) may mimic IIH clinically. Imaging findings may be misleading due to hypoplastic sinuses or re-canalized thrombosed sinuses. The sensitivity and specificity of different MR sequences to exclude thrombosis is unknown. The aim of this study was to retrospectively review the MRI/MRV findings on a large series of patients with IIH seen at our neuro-ophthalmology department.
Methods: :
Systematic, retrospective expert review. Available MRI and MRV studies from a series of patients with IIH previously reported (Villate, N., ARVO 2007) were retrieved. All available images were reviewed for image quality and assessment of dural sinuses by a neuro-radiologist at the University Of Kansas Department Of Radiology. Collected data was transferred to a spreadsheet, coded and analyzed using ratios.
Results: :
37 MRI and 29 MRV studies were reviewed. 94.6% and 91.9% of the MRI had T1SE and T2SE sequences respectively; only 5.4% had T2*SW sequences. 86% of the MRV studies had 2D TOF sequences and 6.9% had 3D TOF sequences. Individual visualization of the dural venous sinuses, internal cerebral vein (ICV), vein of Labbe (VL) and vein of Galen (VG) was overall better with MRV. Abnormalities in both transverse sinuses (TS) were found in 30.9%. Visualization of the TS with MRI was excellent in 59% for the right TS and 51% for the left TS. MRV improved these percentages to 76 % and 66% respectively. The incidence of hypoplastic sinuses was 38%. Initial reports described TS abnormalities in approximately 5% of the cases, whereas the neuro-radiologist made the observation in 31% of the cases.
Conclusions: :
Standard MRI and MRV techniques allow no definite confirmation or exclusion of CVST. The transverse sinuses are difficult to visualize with standard MRI and MRV techniques. T2*SE MRI sequences and 3D TOF MRV sequences may improve image quality but are still not used routinely to study patients with IIH. A significantly higher percentage of abnormalities were found when a neuro-radiologist read the films. The occurrence of hypoplastic sinuses in our series appears higher than reported for the general population.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • neuro-ophthalmology: diagnosis • visual impairment: neuro-ophthalmological disease