MRI Instructions

SJK

February 20, 2003

  1. Before you start, make sure the system is set up for imaging. There should be a "Set Up for Imaging" sign on the magnet, & you should see wooden blocks at the top of the magnet holding up the center tube.
  2. Sign the logbook.
  3. Turn on the temperature controller on the right side of the instrument rack. Do this by pressing the I/O button. Adjust the temperature set point if necessary. This is done by pressing the circular arrow button at the right end of the white stripe. A little green thermometer with two arrows appears. Press the up/down arrows next to the flashing temperature to change the set point, then press the circular arrow button once more. Do NOT set the temperature above 20 C or below 4 C. and do NOT change the alarm points.
  4. Turn on the gradient power supplies. Open the cabinet on the right and turn on each gradient with its red on/off switch. After the little red lights go out, press the Protection Reset button on the top panel. The red Amplifier Shutdown warning lights should go out.
  5. Place your sample in the probe and insert it in the magnet. The probe inserts from the bottom, and is held in place with knurled screws. Make sure you position it according to the mark that shows how far to insert it. Connect the black cable labeled 1H to the 1H BNC connector.
  6. Log in. On the SGI computer, enter your user name, press the enter key, then type in your password.
  7. Click once on Pv2.1.1 to start the software. Click on the okay button to close the ParaVision System Control error message. Do not close the XWIN-NMR window - it is necessary that this window be open for ParaVision to run.
  8. Register for your scan - choose New Patient and fill in the name & registration lines. You can put a number in the registration line. The other fields are optional. Click on Accept. Then fill in the Study name. Leave the location as "wc" and the Entry as Head First (this makes the head direction toward the ceiling.). For setup purposes, choose onepulse from the protocol list.
  9. Open the Image Display Window (Tools-> ImageDisplay(xtip) )
  10. Open the toolbox. On the ParaVision ScanControl menubar, click on the tools icon (far right side).
  11. Tune & match the probe to your sample. Start the display by choosing Wobble on the pull down menu under Acq on the Spectrometer Control Tool window. Adjust the capacitors on the probe using the T & M knobs closest to the 1H cable on the probe until the dip in the acqDisplay window is centered (tuned) & reaches the bottom (matched). Then click the Stop icon on the Spectrometer Control Tool Window display.
  12. Shim the magnet for your sample. Choose AutoShim XYZ under Acq on the Spectrometer Control Tool. When AutoShim starts, grey X's appear over GSP & GOP. When the X's disappear, autoshim is done.
  13. Set the reference frequency by selecting Auto Set on Resonance under the Acq menu on the Spectrometer Control Tool.
  14. Run some scout images. Click the New Scan button on the ParaVision ScanControl window and then select tripilot_gefi as the protocol. Then click on GSP to start collecting signal for setting up the scan. Adjust the signal level to 50% by moving the Receiver Gain slide bar. Set the transmitter attenuator (Tx Attenuator 0) to 30 to start, then adjust it for maximum signal. Readjust the Receiver gain so that the signal level is about 80%. Then hit Stop, then GOP to acquire the images. A colored bar in the ParaVision ScanControl window shows your progress. When the images are done, you can display them all in the image display window by holding down the shift key while you use the middle mouse button to transfer the images to the ImageDisplay window.
  15. Continue with your scans. You can start a new scan by clicking in the New Scan button on the ParaVision ScanControl window. Choose your protocol from the list. One popular one is msme-bio (multi-slice multi-echo). I'll describe the basic setup for this protocol.
  16. Set up the geometry for your scans. With the new scan selected, click on the button with the yellow stripes on the ParaVisionScanControl window. In the new window that opens, you may select a reference image using the Load Reference button at the bottom of the display & the Slice button at the top right corner of the display. Then choose the basic orientation of the slices you would like to prescribe by using the button at the top of the column of buttons on the right. You may also choose the number of slices you would like ("Slices" in the same column.) You can adjust the position, thickness, spacing, and field of view of the slices that you have prescribed by clicking on the tilted slice button on the left. It is the third button down in the right column of buttons.
  17. Click on GSP to set up the scan. For msme scans, start with Tx Attenuator0 set to 20, Tx Attenuator1 set to 14, and make sure that the Independent Scale button does NOT have a red check mark in it. Use the Receiver Gain slider to adjust the signal level to 50%, then adjust the transmitter levels to maximize the signal. Finally adjust the Receiver Gain to about 80%. Click on GOP to acquire the images.
  18. Continue... You can repeat the same scan by "cloning" the scan. This is done by highlighting the scan in the scan list by clicking with the right mouse button. Then use the middle mouse button to get a menu of options, and choose "Clone Scan." Note that you can also Delete Scan to get rid of a scan, and Remove Scan From List to simply remove a scan from your list (without deleting the data). It is a good idea to delete useless scans and also to remove scans from your list. When you log in, all the scans on your list are loaded and this can take a long time!
  19. Shutting down. Remove your sample from the probe, log out of ParaVision (Choose Exit from ParaVision from the File menu on the ParaVision SystemControl window). Log off of the computer. Turn off the gradient amplifiers in the cabinet, and turn off the water chiller.