Brain MRI

MRI scan is avoided in the following individuals unless evaluated for safety:

• Pregnant women, especially in the first trimester 
• People with metal implants in the body, such as:
  • Ear implants 
  • Aneurysm clips
  • Cardiac defibrillators 
  • Pacemakers
  • Metal coils placed in blood vessels
• People having metal fragments anywhere in their body

A brain MRI is also ordered to detect conditions that affect the brain, such as:

• Birth defects 
• Infection 
• Hormonal disorders (Read more: Hormonal imbalance symptoms)
• Tumours
• Stroke (a condition that occurs when blood flow to the brain is suddenly cut off)
• Bleeding
• Multiple sclerosis (a condition that affects the covering of nerve cells)

Your doctor may order this test to determine the cause of symptoms, such as:

• Speech difficulties 
• Vision problems 
• Hearing loss
• Muscle weakness, numbness or tingling 
• Changes in thinking or behaviour 
• Headache along with some other symptoms
• Loss of memory, thinking and reasoning skills

You do not have to skip meals or medications before the test unless instructed by the doctor. Make sure to wear loose clothing without metal ties on the day of the test. Alternatively, you may be given a hospital gown to wear. 

Inform your doctor if you have a fear of closed spaces. He/she may give you a mild sedative before the test. Read more: Claustrophobia symptoms

Tell your healthcare practitioner and the radiologist if you are pregnant or allergic to the contrast material. Do not carry any metal items inside the MRI room, as it can cause burns. These items include:

• Mobile phones 
• Electronic watches 
• Pens
• Pocket knives 
• Eyeglasses
• Jewellery
• Watches 
• Credit cards
• Hairpins

The following procedure is followed for a brain MRI:

• A technician will position you on the scan table and place a plastic device around your head.
• If a contrast injection is required, it will be given through a vein in your arm. 
• The scan table will slide into the tunnel-like opening of the scanner. 
• The technologist will control the scanner from another room and take images of your head. 
• He/she can communicate with you through speakers available inside the scanner. 
• A call button will be provided in case you have any problems during the procedure. 
• You will be given a headset to block out noises made by the scanner.
• Make sure to lie very still during the test, as movements can distort or blur the scan images. 

The test usually takes about 45 minutes.

The procedure itself is painless; however, some individuals may find it uncomfortable to lie still for a long time.

You may hear intermittent clicking, humming and knocking sounds from the scanner. The technician will give you a headset to cancel the noise.

After the test, you may feel some warmth in the scanned area.

If a contrast dye is injected, you may experience a feeling of coldness, headache, metallic taste in the mouth or nausea after the test. Though, these effects usually last only a few moments.

The following conditions can be diagnosed through a brain MRI:

• Infection of the brain or skull bones (Read more: Brain infection causes)
• Bleeding in the brain
• Brain damage due to injury
• Brain tissue swelling
• Multiple sclerosis
• Brain tumours
• Fluid collection around the brain
• Structural abnormalities in the brain
• Stroke

MRI is associated with a few risks, such as:

• The strong magnetic field can cause malfunctioning of any implanted medical device.
• In rare cases, the patient develops an allergic reaction to the contrast dye.
• The contrast dye may be harmful to people with serious kidney problems.

The benefits of an MRI are:

• A non-invasive procedure with no radiation exposure 
• Gives detailed images of the brain that are clearer than those obtained from other imaging studies 
• Detects abnormalities that may be obscured by bone
• Detects stroke at a very early stage

You can resume your usual diet and activities after the test. However, if a contrast dye is used, you will be monitored for some time for side effects such as itching, swelling, rashes or difficulty breathing. Inform your doctor if you observe any pain or swelling at the site of injection. If a sedative is given, you will be asked to rest until its effects wear off.

A contrast dye may be used to enhance the image quality of the brain MRI. The dye is usually administered to diagnose certain conditions such as tumour and cerebral abscess; however, it is not needed for the diagnosis of conditions such as an aneurysm.

Due to the use of a dye, there is a risk of allergic reaction from contrast MRI while a non-contrast MRI carries no such risk.

After a contrast MRI, the patient has to be monitored for a while for any side effects from the dye. However, you can directly go home after a non-contrast MRI.

A contrast MRI can be risky for those with kidney problems while it is not the case with a non-contrast MRI.

Additional tests ordered will vary with the condition suspected but may include:

• Lumbar puncture
• Nerve function study
• Carotid ultrasound 
• Cerebral Angiography
• Echocardiogram 
• CT scan

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.