Why is an MRI so noisy?!
Question: i just had one today. i thought it was just going to be one constant noise. i felt like i was in a movie or something with all these different sound effects. one of them was a deep "buzzing", and another one sounded like i was being shot at.
so my question is...what do these sounds mean? and do the different sounds mean that the machine is doing different things?
thanks! i'm really curious!
Answers: i just had one today. i thought it was just going to be one constant noise. i felt like i was in a movie or something with all these different sound effects. one of them was a deep "buzzing", and another one sounded like i was being shot at.
so my question is...what do these sounds mean? and do the different sounds mean that the machine is doing different things?
thanks! i'm really curious!
The magnet in a MRI machine is stationary. Nothing moves!
The noise is made by RF signals.
"Although there are no moving parts inside and MRI scanner, noise is generated when powerful Radio Frequency (RF) electrical pulses are turned on and strong electromagnetic fields are switched off and on rapidly."
http://www.wmopenmri.com/faq.html
The different types of noises are from different length of pulses, which give us different types of images. A spin echo sequence uses different machine settings than a STIR....
Interestingly enough, open MRI scanners are much quieter than the traditional, tunnel MRIs.....Some of my patients find the noise almost hypnotic and others are annoyed by the sound.
MRI's use sound and magnetic fields to produce the images. When the sounds change, it does mean that they are taking different types of pictures. Its really no big deal, just annoying.