| Question |
Answer |
| 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) |
500 Words
