Chordae Willisii of the dural sinuses: an anatomical study using magnetic resonance imaging

Purpose The chordae Willisii (CWs), trabecular projections into the lumen of the dural sinuses, are not well understood. We aimed to explore them using magnetic resonance imaging (MRI). Methods Eighty-five patients underwent volumetric contrast-enhanced MRI, while another 30 underwent a fluid-attenuated inversion recovery (FLAIR) sequence in the coronal section. Results The CWs were detected as linear filling defects lying in the dural sinuses, adjacent to the surrounding dura mater. They were found in the superior sagittal sinus (SSS) in 68.2% of the patients, most frequently in the middle third, with laminar appearance. In 27.1% of the patients, the CWs divided the SSS lumen into separate channels. The CWs were identified in the transverse sinus, transverse-sigmoid sinus junctional area and sigmoid sinus, and straight sinus in 54.1, 47.1, and 8.2%, respectively. On the FLAIR images, dural septi partially dividing the SSS lumen were identified in all patients. In addition, in 73.3% of the patients, fine linear structures were observed in the lumen with inconstant arrangements. Conclusions The CWs may be constant structures distributed over the lumen of the intracranial dural sinuses. Contrast-enhanced MRI may be useful for detecting laminar CWs. The FLAIR sequence may be advantageous for delineating the dural septi projecting into the lumen of the dural sinuses.