Some MRI scans involve having an injection of contrast agent (dye). This makes certain tissues and blood vessels show up more clearly and in greater detail. Sometimes the contrast agent can cause side effects, such as: feeling or being sick.
In a new study published in Current Biology online on Sept. 22, a team led by Johns Hopkins scientists suggests that MRI's strong magnet pushes on fluid that circulates in the inner ear's balance center, leading to a feeling of unexpected or unsteady movement.
Transient reactions
The most common adverse reactions are minimal: headache, nausea (feeling slightly sick) and dizziness for a brief time after the injection. A few patients will have a feeling of coldness at the injection site.
Vertigo induced by exposure to the magnetic field of a magnetic resonance imaging (MRI) scanner is a well-known phenomenon within the radiology community but is not widely appreciated by other clinical specialists.
Several studies have shown that MRI causes severe anxiety in 37% of patients, even those who state that they are not claustrophobic, and 5–10% cannot complete MRI due to claustrophobia [7].
Sensations of self-motion and vertigo are common among patients and technologists near MRI scanners and especially near stronger magnetic fields.
A new study suggests, however, that MRI machines do, in fact, manipulate brain activity—and they change the brain in a way that helps treat depression. In other words, MRIs may be unintentional antidepressants.
Diagnostic Imaging
The MRI machine uses a combination of a strong magnet, radio transmitter and receiver. When the sequences are performed, electric current is sent through a coiled wire-an electromagnet. The switching of the currents causes the coils to expand making loud clicking sounds.
A head MRI scan can diagnose issues having to do with the brain, nerves of the brain, inflammation in the head, inner ear problems, and the spinal cord.
Since the MRI machines are magnets, it is best to not apply deodorants, antiperspirants, perfumes, or body lotions before the examination. These items contain metals that might interfere with the magnetic field inside the MRI machine and cause you to have distorted images and wrong results.
There also aren't any restrictions on what you can do after the test. “Patients can resume their normal activities immediately after the MRI scan,” Dr. Taouli says. (Unless you had any drugs for sedation or anxiety, in which case you may need someone to drive you home; be sure to ask your doctor about this beforehand.)
Immediately after the MRI
There are no known long-term side effects from undergoing MRI. The MRI scan does not use ionising radiation to achieve its pictures. The MRI scan is a non-invasive, painless and safe procedure that doesn't require any 'recovery time'.
The MRI personnel will ask you many questions to determine if you can safely be imaged. You will also be asked you weight and height. This information will allow the pulse sequence to adhere to the specific absorption rate (SAR) limitations described in Chapter 9, and the proper choice of imaging hardware.
When not properly accommodated during an MRI, claustrophobic patients may experience panic attacks, which can bring on increased heart rate, difficulty breathing, chills, sweating, and other distressing symptoms. Claustrophobia is a very common condition, affecting as much as 5% of the population.
Skin-to-skin contact during MRI can cause the scanner to emit high-power electromagnetic radiofrequency pulses that are conducted through the body, creating heat.
The definitive test is an MRI scan with contrast. MRIs can identify tumors as small as 1 mm. Some patients have an MRI scan performed for a common complaint, such as a headache, and this MRI ends up spotting an acoustic neuroma.
MRI is preferred over CT due to its superiority in visualizing the posterior fossa, which is often the location for a central etiology of vertigo. MRI will rule out acute and chronic ischemic disease, cerebellopontine lesions such as vestibular schwannomas and meningiomas, as well as multiple sclerosis.
The inflammation can be measured in several ways. First, it can be seen on an MRI scan of the brain. Areas of inflammation take up a contrast agent called gadolinium, and show up brightly on MRI. When inflammation occurs, there is an increase in certain kinds of molecules called cytokines.
MRIs take a long time to complete because they take many hundreds of images of your tissue in slices. They then build this up into a three-dimensional representation that doctors can study.
The banging is the vibration of metal coils in the machine caused by rapid pulses of electricity, said Dr. Keith Hentel, chief of emergency/musculoskeletal imaging at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.
Some MRI scans involve having an injection of contrast agent (dye). This makes certain tissues and blood vessels show up more clearly and in greater detail. Sometimes the contrast agent can cause side effects, such as: feeling or being sick.
The magnetic fields that change with time create loud knocking noises which may harm hearing if adequate ear protection is not used. They may also cause peripheral muscle or nerve stimulation that may feel like a twitching sensation. The radiofrequency energy used during the MRI scan could lead to heating of the body.
Unless you're having an fMRI, any brain scans from traditional MRIs will only show structural elements. So, even if you feel a brief spike of stress in the beginning of your MRI before you start to relax, medical staff won't have access to any insights into your thoughts or feelings.
You won't have pain from the magnetic field or radio waves used for the MRI test. But you may be tired or sore from lying in one position for a long time. If a contrast material is used, you may feel some coolness when it is put into your IV.