In-Class Questions

1. Can the same coil be used to tip the spins, and measure the MRI signal?

   
   
   
   
   
   
   
   

2. Assume $T_{1}$ = 800ms, $T_{2}$ = 40ms, and $B_{0}$ = 1.5T, compare the time derivatives of $e^{-t/T_{1}}$, $e^{-t/T_{2}}$, and $e^{-i\omega_{0}t}$. Which derivative is largest?

   
   
   
   
   
   
   
   

3. Assume that want to image smaller volumes (voxels) in an image. If reduce in-plan resolution from $\Delta x$ by $\Delta x$ to $\Delta x/2$ to $\Delta x/2$. How much is the signal from the volume reduced?

   
   
   
   
   
   
   
   

4. How does the signal scale with field strength, receiver coil sensitivity, sample volume, sample temperature???

   
   
   
   
   
   
   
   

5. Assume you sample signal at four times the Larmor Frequency. You will be sampling at least two channels. At 1.0T how much data per second will you be collecting?

   
   
   
   
   
   
   
   

6. Assume another nucleus is present in the body, but has half of the gyromagnetic ratio of $^1$H. If the other nucleus is present in equal abundance, what is the ratio of the signals from each nucleus?

   
   
   
   
   
   
   
   

7. Given $T_{2}$ = 40ms and $T_{2}^{*}$ = 10ms, find $T'_{2}$

   
   
   
   
   
   
   
   

8. How does signal depend upon $T_{R}$ in the limit that $T_{R}/T_{1} <<1$? What does this imply for the signal in the limit that $T_{R} \rightarrow 0$?

   
   
   
   
   
   
   
   

9. Given two spins in slightly different fields $\Delta B = 3.5$ppm between the spins is, $B_{0}$ = 1.5T. How long will it take for the spins to get $\pi$ radians or $180^{\circ}$ out of phase

   
   
   
   
   
   
   
   

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