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MRI Vertigo Study Has Dizzying Implications

September 26, 2011
Written by: , Filed in: Diagnostic Imaging, Neuroradiology
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A new study claims to have solved the mystery of why MRI, especially with the most powerful machines, often induces vertigo. It also calls into question the results of all functional MRI research on brain activity.

The study, carried out primarily by researchers associated with the Johns Hopkins University School of Medicine, suggests that powerful MRI magnets interact with natural ionic currents in the fluid of the inner ear. The interaction sets up something called the Lorentz Force, which apparently is quite familiar to physicists, of which I am not one and therefore of which I had never heard.

In essence, the magnetic field induces a force that shoots off at a right angle to the direction of both the ionic current and the magnetic field. That force pushes against the motion-sensing cells that line the inner ear, confusing them and creating dizziness.

For a much more technically correct explanation, see the study, which was published online last week in the journal Current Biology.

The researchers exposed 10 healthy volunteers and 2 volunteers who had no labyrinthine function (no sense of balance) to static magnetic fields from a 3 Tesla or 7 Tesla MRI machine. The healthy volunteers all exhibited “a robust nystagmus” (involuntary, jerky eye movements associated with motion sickness). The subjects without labyrinthine function showed no nystagmus, thus indicating the inner ear as the source of the dizziness.

What makes this study’s conclusions startling, even ominous, is the implication that MRI may alter the flow of body fluids as it measures that flow. If true, that casts doubt on fMRI studies of the brain, because such studies use blood flow as an indicator of brain activity.

The Johns Hopkins researchers observed these effects with a static magnetic field. How much more contaminated would be the results from the varying magnetic fields of an actual MRI scan?

We’ll definitely be watching this topic for further developments.

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Monday means at least one good thing: a new post on our Facebook page.

Related seminar: National Diagnostic Imaging Symposium

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