21 Questions
What is used to produce information in MRI?
Hydrogen
What causes T2* decay in MRI imaging?
Magnetic susceptibility in the patient
What is aliasing artifact in MRI imaging?
It occurs when there is an eddy outside of the field of view in the phase direction
What is Nyquist's frequency theory?
It states that we have to sample at least two times the maximum frequency in order to pull information correctly from our patient
What are the different forms of magnetic susceptibility?
Diamagnetism and paramagnetism
What is the purpose of refocusing pulses in MRI imaging?
To allow for more accurate trend of decay and T2 contrast
What happens to hydrogen in a strong magnetic field?
It becomes a tiny magnet
What is the purpose of RF pulses in MRI imaging?
To produce resonance in a patient
What is quenching in relation to superconducting MRI units?
The process of turning the magnetic field off
What is chemical shift artifact in MRI imaging?
It occurs due to the difference in resonant frequency between fat and water molecules
Which type of MRI image weighting is optimized by shorter TR and TE values?
T1 contrast
How do longer TR and shorter TE affect T1 and T2 contrast in proton density-weighted sequences?
Longer TR reduces T1 contrast, while shorter TE reduces T2 contrast
What is magnetic susceptibility artifact in MRI imaging?
It is the magnetism in the patient and can cause inhomogeneity in tissue or implant areas
What do proton density-weighted images aim to identify in a tissue?
The amount of hydrogen
What does diffusion measure in MRI?
Brownian motion, which is the thermal movement of water
What is the process used in MRI imaging to generate images of the body?
Strong magnetic fields and radio waves
What is the purpose of quality control tests on MRI equipment?
To ensure the equipment is functioning appropriately and within specific limits
What is partial volume artifact in MRI imaging?
It occurs when a thick slice is used in imaging
What is the purpose of the phase encoding gradient in MRI imaging?
To separate the k space into multiple lines
What does perfusion measure in MRI?
How well nutrients get to tissues
What is the purpose of motion reduction techniques in MRI imaging?
To avoid motion artifact
Study Notes
- MRI uses hydrogen to produce information from patients.
- Hydrogen has a magnetic moment and directional magnetism.
- Hydrogen wobbles on its axis and generates a charge, becoming a tiny magnet.
- The rate of hydrogen's precessional motion is important in generating resonance.
- A strong magnetic field aligns hydrogen either parallel or anti-parallel to it.
- RF pulses can manipulate the direction of hydrogen and change net magnetism.
- Resonance is the process of adding energy to hydrogen and shifting net magnetism.
- Hydrogen in phase coherency behave the same way and are in sync.
- After an RF pulse, hydrogen in the transverse plane start to decay and move back to their starting point.
- MRI measures the change in hydrogen during these processes to produce images.
- MRI measures hydrogen in different tissue types.
- T1 contrast is dependent on the tissue's unique T1, which determines how quickly the longitudinal magnetization recovers.
- T2 and T2* measure magnetic susceptibility and neighboring protons.
- T2* is sensitive to magnetic susceptibility and not accurate.
- PD measures the density of hydrogen and net magnetism in the tissue.
- Flow is a challenge in MRI as it involves moving hydrogen, and gradients are used to optimize the image.
- Diffusion measures Brownian motion, which is the thermal movement of water.
- Perfusion measures how well nutrients get to tissues.
- MRI holds diagnostic value in understanding strokes and other conditions.
- MRI uses different techniques to measure tissue characteristics.
Do you want to test your knowledge on how MRI works and the science behind it? Take this quiz and learn about the role of hydrogen in producing images, the principles of resonance and phase coherence, and the different techniques used to measure tissue characteristics. This quiz includes keywords such as resonance, T1 contrast, T2, PD, flow, diffusion, and perfusion. Test your understanding of MRI and its diagnostic value in identifying various conditions.
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