Published on: Mar 3, 2016
Transcripts - Narration (19.0K)
In positron-emission tomography, radioactive tracers emit positively-charged electrons called positrons.
These positrons encounter electrons, and they annihilate each other to produce two gamma particles.
Gamma particle detection from several angles, in conjunction with computer imaging, produces accurate
images of soft body tissues.
PET is particularly useful in diagnosing Alzheimer’s disease in brain tissue. Nuclear magnetic resonance
imaging, or MRI, is a popular diagnostic technique, because it does not submit the body to dangerous high-
energy particles. MRI is performed by placing the person in a large cylinder that contains a strong magnet.
The magnetic fields of the atoms of the body are caused to resonate by the introduction of radio waves. A
computer interprets the signals put out by the resonating atoms to produce a two-dimensional view of the
body. The MRI is especially useful in detecting abnormalities in soft body tissues.