Pulse Sequences: MR Signals
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MR Signal Q&A's
- Where does the MR signal come from?
- Isn't the MR signal just re-emission of absorbed radio waves?
- What is a free induction decay (FID)?
- What is a gradient echo, and how does it differ from an FID?
- What are TR and TE?
- How is a spin echo generated?
- You mentioned that other pulses besides a 90°-180° combination can produce a spin echo. I don't see how this happens. Can you explain?
- What is a stimulated echo?
- Are stimulated echoes used for imaging? I've never heard of that.
- If a spin echo results from 2 pulses, and a stimulated echo from 3 pulses, what do you get from 4 pulses?
- What is a partial flip angle pulse, and why would you want to use one?
- Wait a minute! If a partial flip angle pulse tips less magnetization into the transverse plane than a 90° pulse does, how can the signal be higher?
- How do you pick the "optimum" flip angle?
MR Signal Topics