University of Wisconsin - Madison Materials Research Science and
Engineering Center Education
and Outreach

Magnetic Resonance Imaging

See our web page on Nuclear Magnetic Resonance


Open Magnet Design MRI

In 1952, Bloch and Purcell won the Nobel Prize in Physics for the development of the analytical technique known as nuclear magnetic resonance (NMR). Magnetic resonance imaging (MRI) is an adaptation of NMR for medical diagnostic purposes.

Both NMR and MRI rely on the fact that some atomic nuclei have a magnetic moment associated with their spinning. The most common nuclei studied using NMR are H-1, C-13, F-19 and P-31. Most MRI studies involve the H-1 nuclei in water.

The isotopes listed above have two spin states. When these nuclei are exposed to an external magnetic field, their spins can be parallel or anti-parallel to this external field. Transitions between these two spin states can be induced with energy from radio waves of the proper frequency. A radio frequency (rf) signal is transmitted to the sample, which has been placed in a strong magnetic field. The nuclei of atoms in the sample interact with the rf signal. A rf receiver measures the signal after its interaction with the sample. The analysis of these measurements can help to identify the structure of the sample.

MRI instruments are massive pieces of equipment. Some representative specifications from an instrument manufacturer are collected in the table below.

Bruker Full-size whole-body MRI/MRS system.
 
MEDSPEC 30/80
MEDSPEC 30/100
MEDSPEC 40/80
Magnet-field strength
3 Tesla
3 Tesla
4 Tesla
Bore, diameter of patient instrument cavity
80 cm
94 cm
80 cm
Max. gradient strength
45 mT/m
30 mT/m
45 mT/m
Magnet weight
7.8 tons
12 tons
13 tons
Body region
to be examined
brain, extremities,
cardiac, and spine
whole-body
brain, extremities,
cardiac, and spine

Other MRI web sites.


Sites describing MRI


Magnetic Resonance Imaging (MRI) - Body
http://www.radiologyinfo.org/en/info.cfm?pg=bodymr

Magnetic resonance imaging - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Magnetic_resonance_imaging

How Stuff Works: Magnetic Resonance Imaging (MRI)
http://www.howstuffworks.com/mri.htm

R. de Beer
University of Technology Delft
Department of Applied Physics
P.O. Box 5046, 2600 GA Delft, The Netherlands
Basic principle of MRI

The Basics of MRI
http://www.cis.rit.edu/htbooks/mri/


Suppliers of MRI Equipment


General Electric Healthcare

For the latest in MRI diagnostic equipment
http://www.gehealthcare.com/usen/mr/signahdx_30t/index.html


This MRI unit is used in the operating room during surgery. For more information, see:
http://www.gehealthcare.com/usen/mr/products/mrsurgical_suite.html


Bruker

http://www.bruker-biospin.de/MRI/products/medspec.html

<NMR/MRI Simulator with Movies!] | [Other NMR Sites>

This page was designed and is maintained by

Dr. Mike Condren


Exploring the Nanoworld   |   MRSEC Nanostructured Interfaces
Copyright © 2006 The Board of Regents of the University of Wisconsin System.