MAGNETIC RESONANCE IMAGING Flashcards
What is MRI?
A computer-based imaging modality using magnetic fields and radio waves.
What was MRI originally called?
Nuclear Magnetic Resonance.
What is the main advantage of MRI?
Best low contrast resolution.
Why is MRI non-invasive?
It does not use ionizing radiation.
How does MRI differ from conventional radiography in contrast?
MRI contrasts depend on electromagnetic interaction, not x-ray attenuation.
Who discovered the properties of magnetic resonance in the 1940s?
Felix Bloch and Edward Purcell.
What year did Paul Lauterbur publish the first MRI cross-sectional image?
1973
What was the name of the first MRI machine?
Indomitable.
A spurious finding or distortion in the image.
ARTIFACT
What is “free induction decay”?
Signal emitted by tissue after RF excitation.
What is the gyromagnetic ratio of hydrogen?
43 MHz/T.
What does the Larmor frequency describe?
The frequency at which a nucleus precesses in the magnetic field.
indicates power absorbed during RF irradiation.
Specific Absorption Rat (SAR)
What is T1 relaxation time also called?
Spin-lattice relaxation time.
What does T2 relaxation time represent?
Spin-spin or transverse relaxation time.
What is the SI unit of magnetic field strength?
Tesla (T).
Why is hydrogen used in MRI?
It is the most abundant element in the body and creates the strongest MRI signal.
What is the purpose of spin echo sequences?
To produce T1-weighted images and proton-density-weighted images.
What is the function of FLAIR sequences?
Suppressing signals from cerebrospinal fluid (CSF).
What is the primary use of T1-weighted images (T1W)?
Showing anatomical detail.
What are T2-weighted images (T2W) useful for?
Highlighting pathology.
Localizes the MRI signal, enabling slice selection and spatial encoding.
gradient magnetic field
Produces gradient magnetic fields for imaging.
gradient coils
What is the main function of the operating console in MRI?
To control the computer and imaging parameters.