Physiologic Flow Related Signal Intensity in Dural Sinuses on Time of Flight Magnetic Resonance Angiography: Changes Caused by Head Elevation

Purpose: The presence of a flow-related signal in the normal dural sinus time of flight magnetic resonance angiography (TOF MRA) is common. This study aimed to identify changes in signal intensity in the dural sinus caused by changes in patient position. Materials and Methods: The researchers performed an elevation TOF MRA of the cerebral region in 52 patients, who showed abnormal flow-related signals in the dural sinuses on supine position. Flow-related signal intensity in the dural sinuses was then analyzed. Results: Flow-related signals were seen in 114 sites (52 patients), specifically in the internal jugular vein (IJV), sigmoid sinus (SS), inferior petrosal sinus (IPS), and cavernous sinus (CS) in 29 sites, 33 sites, 32 sites, and 20 sites, respectively. After head elevation, flow-related signal changes were then observed in the IJV, SS, IPS, and CS in 107 sites (107/114, 93.9%). There was loss of signal (62/114, 54.4%), or decrease (39/114, 34.2%), increase (6/114, 5.3%), or no change (7/114, 6.1%) in the signal intensity, and flow related signals were more frequent on the left than on the right. Conclusion: Flow-related signals in the dural sinuses on TOF MRA were decreased or disappeared by head elevation in 88.6% of the sites. Head elevation may help distinguish between pathologic and physiologic states.