Inferior sagittal sinus: magnetic resonance imaging study

Purpose To date, no study has explored the inferior sagittal sinus (ISS) using neuroimaging modalities. This investigation aimed to characterize it using magnetic resonance imaging (MRI). Methods A total of 77 patients with intact cerebral hemispheres and covering meninges underwent thin-sliced, contrast-enhanced MRI. Results The ISS was well delineated as a linear structure with a constant diameter in 97% of the patients. The maximum intensity projection (MIP) images well delineated the three-dimensional architecture of the ISS and relevant veins. The identified ISSs could be classified into three different types, with the underdeveloped type being the most frequent at 47%. In addition, the ISSs showed considerable variability both in the original site and course along the lower margin of the falx cerebri. Furthermore, in 22% of the cases, fenestrations were identified in the falx cerebri adjacent to or near the ISS. More than 70% of them were located in the middle third of the falx, followed by the anterior and middle thirds of the falx. Conclusions The ISS is a constant venous structure characterized by morphological variability and may function as an adjunctive or assistive venous drainage route. Thin-sliced, post-contrast-enhanced sagittal MRI combined with MIP imaging is useful for exploring the ISS.