MRI Scans CAN Cause Vertigo

Researchers at Johns Hopkins published a study that reports that MRI scans CAN cause feelings of dizziness induced by magnetic fields causing motion of the electrically charged fluid of the inner ear.

In both ears, there is a "gyroscope" called the labyrinth. Whenever the head turns or a force like gravity is exerted on this system, fluid moves within which tells the brain that motion has occurred. It's much like looking into a glass of water and based on the way the water tilts in the glass, you can guess which way motion is occurring.

In any case, the study took two groups of people, one with an intact labyrinth system and another without a functioning labyrinth system. Only those individuals with an intact labyrinth system suffered vertigo while getting an MRI. Furthermore, the stronger the MRI's magnetic field, the worse the vertigo.

Beyond the "that's interesting" trivia, these results are VERY important in any type of brain activity research. Why? Well, if a person is feeling dizzy, the brain activity you may be studying using the MRI may be attributable to the dizziness itself and the patient's coping mechanisms to deal with it rather than whatever brain activity research you may be investigating.

On a more science-fiction note, based on these findings, an MRI can theoretically be used to potentially diagnose and treat dizziness due to the inner ear. After all, if it can cause dizziness, it certainly can be used to help it as well!

Reference:
MRI Magnetic Field Stimulates Rotational Sensors of the Brain. Current Biology, 22 September 2011. doi:10.1016/j.cub.2011.08.029

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Patients with Iodine or Seafood Allergy CAN Receive Contrast During CT Scans

It is a prevalent belief out in the medical (and lay public) community that patients with iodine or seafood allergy can not receive contrast when undergoing certain radiological tests like CT or MRI scans. The concern is that contrast contains minute amounts of free iodide and as such, IV administration of this material puts the patient at risk of a life-threatening anaphylactic reaction.

Contrast is often given in these tests as it traces out bloodflow enabling the physician to see organ and mass architecture much more clearly allowing for improved accuracy in seeing anything abnormal.

Well... rest assured that patients with iodine and seafood allergy CAN receive contrast without any significant increased risk of an allergic reaction as compared to other allergies.

In a large study encompassing 112,003 patients, only 5% had a reaction. The relative risk of a reaction in patients with seafood allergy was 3.0 compared with 2.9 for those with allergy to eggs, milk, or chocolate; 2.6 for those with allergy to fruit and strawberries; and 2.2 for those with asthma [7]. In other words, a seafood allergy increases the risk of a contrast reaction by about the same factor as does any other allergy. At least 85% of patients with seafood allergy receiving IV contrast material will not have an adverse reaction.

Reference:
Formation of potential antigens from radiographic contrast media. Acta Radiol 1987; 28:473-77
Immunologic basis for adverse reactions to radiographic contrast media. Acta Radial 1990; 31:605-612
Contrast media reactions: experimental evidence against the allergy theory. Br J Radiol 1984;57: 469-173
Adverse reactions to intravascularly administered contrast media. AJR 1975;24: 145-152

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Are Doctors Required to Obtain Patient Permission For Posting Non-Identifiable X-Rays, CT Scans, Etc Online?

The blunt answer is no... as long as there is no way the patient can be identified by looking at the image. (in other words, anonymous).

Dr. Ves Dimov at CasesBlog has written a very good article regarding this very question and the guidelines used to determine whether patient permission is required or not.

Read his blog article here.

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Website That Calculates Your Cancer Risk From Radiological Tests

In the last few weeks, there's been multiple media reports on the increased risk of cancer with common radiological tests due to radiation exposure, however minimal it may be.

Due to this concern, a website called "X-Ray Risk.com" was developed that calculates your increased cancer risk based on type of test, age, and gender.

For example, a CT Neck (a common CT test ordered by ENTs) on a 35 year-old male increases cancer risk by 0.046%. A chest x-ray? Only 0.001%.

Check out the website here.

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