A brain MRI is a way to take a picture of your brain without using ionizing radiation. It uses magnetic fields and radiofrequency pulses to produce a very detailed picture. It is crucial for the diagnosis of many neurologic conditions.
The average MRI brain scan takes about 30-60 minutes to complete. To obtain the images, the patient lays as still as possible in a narrow tube, which can be very claustrophobic for some. Additionally, the scanner tends to be very loud because the magnetic fields are cycled on and off, which produces noise. These factors make a brain MRI very difficult for some patients to tolerate. If the patient moves, the pictures are blurry and could be difficult to interpret.
Most MRI scanners are 1.5 Tesla. Tesla (T) is the unit of measurement quantifying the strength of a magnetic field. The stronger the magnetic field, the more detailed the image becomes.
Low Tesla MRIs, like some intraoperative MRIs, are less than 1 T and provide much less detail compared to the standard 1.5 T.
Newer MRI scanners can be as powerful as 3T or 7T. (There is a 9.4T MRI in Chicago used to image rodents). These provide excellent detail due to greater spatial resolution and contrast detection. However they also have greater artifact due to movement or susceptibility from tissues/ materials in the body.
Recently, researchers performed one of the most detailed brain MRI scans ever performed. Over 100 hours were used to scan a cadaver brain using a 7T scanner. This has the resolution to spot objects smaller than 0.1 millimeters.
Of course a living human could never complete a 100-hour scan. Any tiny movement, including those coming from breathing and blood flow, would blur the images. However it makes you wonder how long you could hold still for a detailed image of your brain? For this picture, we don’t want you to say “cheese”.