Comments:
This set of illustrations were created for Scientific American for inclusion in an
article about current medical imaging techniques. The artwork was completed in 7
days. The artwork displayed here is shown in a different form to that finally used.
Description:
Magnetic Resonance Imaging (MRI) is primarily used in medical imaging to visualize
the structure and function of the body. It provides detailed images of the body in
any plane. MR has much greater soft tissue contrast than computed tomography (CT)
making it especially useful in neurological, musculoskeletal, cardiovascular, and
oncological imaging. Unlike CT it uses no ionizing radiation, but uses a powerful
magnetic field to align the magnetization of hydrogen atoms in the body. Radio waves
are used to systematically alter the alignment of this magnetization, causing the
hydrogen atoms to produce a rotating magnetic field detectable by the scanner. This
signal can be manipulated by additional magnetic fields to build up enough information
to reconstruct an image of the body.
Magnetic Resonance Spectroscopy is used to measure the levels of different metabolites
in body tissues. The MR signal produces a spectrum of resonances that correspond
to different molecular arrangements of the isotope being "excited". This signature
is used to diagnose certain metabolic disorders, especially those affecting the brain,
as well as to provide information on tumor metabolism.
Magnetic resonance imaging was developed from knowledge gained in the study of nuclear
magnetic resonance. In its early years the technique was referred to as nuclear magnetic
resonance imaging (NMRI). However, as the word nuclear was associated with ionizing
radiation exposure it is generally now referred to simply as MRI. Scientists still
use the term NMRI when discussing non-medical devices operating on the same principles.
One of the contributers to modern MRI, Paul Lauterbur, originally named the technique
zeugmatography, a Greek term meaning "that which is used for joining". The term referred
to the interaction between the static and the gradient magnetic fields necessary
to create an image, but this term was not adopted.
