Arachnoid granulations in the cerebral dural sinuses as demonstrated by contrast-enhanced 3D magnetic resonance venography

Abstract

Identification of normal filling defects within the intracranial dural sinuses reduces the erroneous diagnosis of the presence of an intrasinus pathologic process. The aim of this prospective study was to assess the prevalence, distribution, and morphological characteristics of arachnoid granulations (AGs) in the dural sinuses. This prospective study was carried out on 110 patients who had both normal conventional brain MRI and contrast-enhanced (CE) 3D turbo flash magnetic resonance venography (MRV). The dural sinuses were viewed on MRV images for the presence of filling defects. The prevalence, site, size, number, shape, outlines, internal structure, and presence of associated cortical vein were determined. One hundred and twenty-six AGs were observed among 71 patients. The superior sagittal sinus was the most common site of filling defects (58 AGs). The mean size of AGs was 6.45 +/- 3.55 mm. Eighty-three percent of AGs were round or oval, with sharp outlines and homogeneous internal structure; of these 81% were associated with cortical vein. In the majority of cases, the identification of AGs can be facilitated by their characteristic appearances: rounded or oval shaped, well-defined outlines and homogenous intensity. The presence of an adjacent cortical vein can be considered as an additional supportive element.