Magnetic resonance imaging (MRI) is a non-invasive way to obtain very detailed images of organs and tissues in the body. In this case, we are looking at images of the brain. This technique appears to be relatively safe and is used in both clinical and research applications. MRI is unlike x-rays or CT scans in that it uses powerful magnetic fields to produce an image, not ionizing radiation. Therefore, MRI is generally harmless.

Scans do not cause any pain and the magnetic fields do not produce any known tissue damage, even with repeated exposure. The most important factor to getting the best quality image is that the child lay as still as possible. Much like photographs, any movement can cause the image to be blurry.

The banging is the vibration of metal coils in the machine caused by rapid pulses of electricity. Inside the scanner are coils of metal wire called gradient coils. When electricity is passed through such a coil, a magnetic field is created. Rapid pulses of electricity cause predictable changes in the field, resulting in tissue changes that can be measured and transformed into anatomic images.

As stronger magnets result in stronger vibrations, the higher the field strength of the MRI scanner, measured in Tesla, the louder the banging.

Below is a sample sound file containing common sounds made by MRI systems. A person’s ears are protected by headphones playing music while the MRI is performed. An MRI technologist keeps in contact with a person during the exam, to make sure they are doing alright and also to give instructions as needed for the test.

So, to hear some sample sounds, click on the file.