Head position matters: Position‑dependent vestibular flow void artifacts in inner ear MRI and their clinical...

It has been shown that static magnetic fields from high-strength magnetic resonance imaging (MRI) machines induce nystagmus in all humans with intact inner ear function. This effect can be explained by the magneto-hydrodynamic Lorentz force, which arises from the interaction of endolymphatic ionic currents and the strong static magnetic field of an MRI machine. Prior experiments demonstrated that MRI-induced nystagmus and vertigo vary with head pitch relative to the magnetic field, being reduced when the head is pitched forward and increased when extended. In another study it has been suggested that signal void artefacts reflected Lorentz-force-induced endolymph movement caused by the interaction between ionic currents flowing through the utricular macula and the static magnetic field of the MRI scanner. Based on these findings the present authors proposed that if the hypointensities are flow voids caused by Lorentz forces, their visibility should also vary with head pitch. In this case, both nystagmus and vestibular hypointensities would share a common mechanism. Twenty healthy volunteers (8 males and 12 females) were recruited to undergo a non-contrast 3 Tesla (T) MRI scan in one of two head pitch positions: chin up (head extension, pitched backward) and chin down (head flexion, pitched forward). A statistically significant increase in hypointensities was observed between the pitched forward and pitched backward positions for both ears (p < 0.01), while no significant differences were detected between corresponding positions of the left and right ears. These findings not only support a Lorentz‑force origin of vestibular hypointensities but also have immediate clinical applicability, with direct implications for radiological interpretation and protocol design to reduce misinterpretation and patient vertigo.