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advanced imaging final 3 MRI

QuestionAnswer
Raymond Damadian reported NMR differences between normal tissue and tumors in 1971
Paul Lauterbur produced the first MRI
1984 first clinical use of MRI
In what plane does an MRI image? any, multi-planar
What produces the image in MRI? nucleons and spin
What role do electrons play in MRI? none
How does a nucleon spin cancel out? there must be two nucleons spinning in opposite directions
What happens when there is an extra nucleon whose spin is not cancelled? there is a net spin
How is an image picked up with MR? the body must have net spin, creating a charge, this charge creates a magnetic field.
What is the target atom for MRI? Hydrogen
Magnetic field strength for MRI 1 Tesla, 10,000 Gauss
Current MRI magnet strength ranges: .06 - 3.5 T
What does MRI do? line up dipoles
Are the dipoles stationary after being lined up? What is this called? no, Lamor wobble/frequency
Lamor frequency formula Hydrogen = 4.26 mHz / Tesla
What causes the dipoles to flip? RF signal at Lamor frequency
Net magnetization the pt becomes polarized
Basic MRI signal: FID – free induction decay
In spin-lattice relaxation time (T1) pathology appears how? black or grey
In spin-spin relaxation time (T2) pathology appears how? white
4 ways we can pulse the RF signal: partial saturation, spin-echo, gradient echo, inversion recovery
MR patients should be screened for what? pacemakers, ferromagnetic aneruysm clips, shrapnel/metallic objects, cochlear implants.
When is the magnet turned off in MR? never (unless unplugged for upgrade)
Created by: annaluz87