How is math used in MRI?

Answer 1

Inside the 'donut' of the MRI machine are a huge number of RF (radio frequency)

sources and RF detectors. After the sources shoot a short, powerful pulse of RF

into you, the sources shut off, and the tissues throughout your body "ring", in

response to the RF they've absorbed, combined with the powerful field of the giant

permanent magnet that's also all around you inside the donut. The detectors

listen to the 'ringing' of your body's tissues from a huge number of different

directions, all around the ring. Each detector hears a ring of a slightly different

level, and hears it fade out after a slightly different time. The signals that are

heard by all of the detectors are compared and combined to give a picture of

what's inside you.

The basic concept of forming the image is the same as in other forms of "tomography" ...

the CT scan, using X-rays instead of RF, and the PET scan, using positron emission

from a radioactive substance.

The math is incredibly complex in each case.

On a completely irrelevant note, but one which I can't bring my self to

conclude without mentioning ... probably my only claim to fame is the fact

that my brother-in-law is one of the names on the original patent granted

to GE for the computed tomography process, and his sister was involved in

some good-science early MRI research when we met in the late 70s. Those

facts and several nickels have bought me many cups of coffee through the

years ever since.