SOP for Spinmaster Relaxometer Start-Up
1) Attach hose to sink spout and open the cold-water tap to maximum. (Check that
the return water is not spraying out of sink and that there is no garbage in the
sink that could potentially block the drain.)
2) Turn on input breakers. The circuit breakers are at the bottom rear of the
relaxometer cabinet. (If the breakers won’t stay latched check to see if the
emergency stop but on the front panel is engaged.)
3) Press the orange button labeled “COMPUTER” to
turn on PC-NMR console computer. (The PC-NMR
console is in a separate metal housing on top of the
relaxometer cabinet. NOTE: The PCNMR console
also has an AC switch on its back above the power
cord that must be switched on if not already so.)
Check to see that the monitor is on and that Windows
XP starts to boot.
Figure 1 PC-NMR Console
Note the orange and
green switch locations.
4) NOTE: The RF transmitter (green button labeled “TX” above computer
power button) should NEVER be on unless the computer is running! As
general practice, turn on the transmitter last - just before starting the
experiment and turn it off first after the experiments are completed. (If the
transmitter is running without computer control, you can hear a highpitched wine from the PC-NMR console box. This sound is the RF section
running amok and should not be allowed to continue.)
5) Turn on the air compressor (Dewalt compressor is
located in the 3T MRI equipment room).
a. Make sure the drain valve on the bottom of the
compressor is closed.
b. Plug the hose connector on the vinyl hose into
the compressor if not already connected.
c. Turn on the compressor (red switch on top of
Figure 3 Air Compressor
compressor). The compressor is noisy and
Figure
2 Air
Compressor
Control
Panel
cycles on and off to maintain adequate pressure Control Panel
in its tank. The tank pressure varies around 200 PSI.
d. Compressor outlet pressure should stabilize at 50 PSI. This is set by a knob
on the panel near the pressure gauge. Pull out to rotate and set pressure. Push
knob back in.
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6) Turn on the VTC (variable temperature control)
unit. The switch is located inside the left
relaxometer cabinet at the top of the rack. The air
flow meter should read approximately a flow of 7-8
l/min. The airflow is adjusted by the metallic knob
next to the flow meter. If adequate flow cannot be
achieved, the outlet pressure of the compressor
should be increased.
7) Set the sample temperature as follows:
a. Press “Reset”.
b. While the display reads “VTC 91”, type 1.
c. Press “Enter”, type in the temperature set
point, and press “Enter”
8) Turn on the relaxometer power supply (black
Figure 4 Spinmaster Hardware
The cabinet on the left contains
the VTC, pump and power
supply control switches.
switch on bottom box inside the left cabinet of
relaxometer). Wait a few seconds to let the system
start-up.
9) Turn on the pump by first pressing the “RESET”
button (yellow button on bottom box) and then the
“PUMP ON” button (green button on bottom box).
You should hear the pump go on. If you don’t hear
the pump go on, press “OFF” (red button) and then
“RESET” and “PUMP ON” again.
Figure 5 From Top to Bottom:
VTC Unit, Power Supply
Control and Magnet Cooling
Pump
10) Press the “RESET” button (yellow button on middle
box inside left cabinet) and then the “ON” button (green button, middle box).
11) Turn on the transmitter on the PC-NMR console (green button labeled “TX” on
the front of the PC-NMR console box).
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SOP for Operation of the Spinmaster Relaxometer
1) Start the software to run the relaxometer by double clicking on the “AcqNMR 95”
icon on the computer’s desktop. Choose “On-Line” in the window that pops up.
2) Turn on the Temperature monitor on the screen by right clicking on the VTC box
(top right corner of screen) and select “Connect”. This information confirms the
setting and current temperature of the sample. Furthermore, the temperature can
be changed from the computer screen by right clicking on the “VTC:” box and
typing in the new temperature
3) Preparing the sample for measurement.
a. The relaxometer uses 10-mm-diameter NMR
tubes. (When ordering sample tubes, you can
specify the cheapest tubes that are available.)
b. The measurement requires approximately 1ml
of liquid – more is okay. Smaller quantities
c.
d.
e.
f.
can be placed in a 5-mm-diameter NMR tube
with cap. A black plastic adapter/holder has
been fabricated for 5-mm tubes.
Place the collar on the sample tube.
Place the tube and collar in the measuring
fixture (on side of relaxometer) and adjust the
collar to ensure that the volume of sample is
centred on the site line of the fixture window.
(See Figure 6.)
Place sample in the relaxometer magnet (the
magnet opening is in the top of the shorter
cabinet on the right) and place the plastic or
brass weight on top. (These weights holds the
tube in the magnet against the air flow that is
used to regulate sample temperature.)
The sample requires approximately 10 minutes
depending on temperature setting and initial
sample temperature for the sample temperature
to equilibrate before beginning the experiment.
Figure 9 Adapter for 5-mm
NMR8Tubes
Figure
Adapter for 5-mm
NMR Tubes
Figure 6 Fixture for Setting
Sample
Positioning
Figure
7 Fixture
for Setting
Sample Positioning
Figure 7 Sample Inserted
4) Tune and match the probe. The “probe” is the rf
into Magnet
Figure
8 Sample Inserted into
coil that excites and detects the sample
Magnet with Weight
magnetization. (This procedure does not need to be done every experiment and
should probably be attempted by more advanced users only.)
a. On the Hardware menu, choose “Tune probe”. For the Spinmaster
equipment, you can ignore the popup window that says “< Set preamp
cables to the tuning position >” as this is now done automatically by the
tune and match box.
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b. Click on the Main par tab. Set the RF attenuation parameter to 10
(Typically this should have a value of 35 units.)
c. On the lower right of the screen click the “mV” tab (it will turn yellow)
and then on the right side of the screen click the down arrow to increase
the display sensitivity.
d. A black trace should appear on the screen with a dip near the red vertical
line in the center.
e. There are two knobs on the bottom of the probe – “Tune” and “Match”. A
small wrench on a wire can be used to turn these potentiometers. The
“Tune” knob tunes the resonant frequency (left to right on screen) and
should be adjusted so that the minimum is centered on the red line. The
“Match” control should be adjusted to maximize the depth of the
minimum. This will likely shift the resonant frequency – readjust with the
“Tune” control and iterate until both adjustments are optimized.
f. Click on the red stop sign when done. Ignore the popup window that says
“< Set preamp cables to the normal position >”.
g. The RF attenuation parameter should return to the previous value (35). If
not, manually set value to 35.
5) Setting the correct frequency.
a. Choose “Acq par” (tab on left side of screen).
b. Choose the “Basic” tab.
c. Click on the “Experiment” box and choose “PP” in the drop down menu
of the window that pops up and then “Accept”. (“PP” is a basic prepolarized experiment.)
d. Choose the “User” tab.
e. Click on the “Data Acquisition File” box and type in the name and
location for the data to be saved to. (Do not use periods in the file name.)
f. Choose the “Main par” tab.
g. Click on the “Polarization time” box and enter a value equal to 3 to 4
times the expected T1 of the sample.
h. The “Recycle delay” box should have the same value that you typed in for
the “Polarization time”. If it does not, enter the value there.
i. Click on the “Relaxation field” box and enter a value, usually 4MHz.
j. Make sure the RF transmitter is on (green button labeled “TX” on the box
on top of the relaxometer).
k. Click on the gun icon (top left corner of screen) to acquire a FID. If the
magnet is off, a window will pop up with the information that the magnet
is off. Click “OK” to turn the magnet on.
l. The display will show a green line (imaginary signal), a red line (real
signal), and a black line (magnitude of real and imaginary). When the
frequency is correct, the real (red) signal will overlay (or nearly so) the
magnitude (black) signal.
m. Click on the save icon (icon of a floppy disk – same as in Microsoft
Office). (The software is logging all experimental parameters and
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measurement results to a file so that you could retrieve this file at a later
date for examination or to re-analyze the data offline.)
n. Click on the correct frequency icon (icon of a bulls-eye with “F1” over it).
o. Repeat the frequency correction (steps k to m) until the correct frequency
is obtained.
6) Obtaining a 900 pulse width.
a. Choose “Acq Par” (tab on left side of screen).
b. Choose the “Basic” tab.
c. Click on the “Experiment” box and choose “ANGLE.FFC” in the drop
down menu of the window that pops up and then “Accept”.
d. Choose the “Main” tab.
e. Click on the “Polarization time” box and enter a value equal to 3 to 4
times the T1 of the sample.
f. Click on the “Relaxation field” box and enter a value, usually 4MHz.
g. Click on the icon of the gun (top left corner of screen) to acquire a FID.
h. Click on the save icon (icon of a floppy disk – same as in Microsoft
Office).
i. Click on the evaluation dialogue icon (This icon is a box with 12 in it on
the top left tool bar on screen).
j. Choose “WAM: Window Absolute Magnitude” from the window that
pops up and then choose “Execute”.
k. In the display window, left click and hold on the peak of the displayed
curve. At the bottom of the screen in the gray bar, the coordinates of the
mouse are displayed. The “x” value is the 90° pulse width in s. Record
this value. (A typical value is between 8 and 9 s.)
7) Estimating the sample T1 value.
a. Choose “Acq par” (tab on left side of screen)
b. Choose the “Basic” tab
c. Click on the “Experiment” box and choose “NP/S” in the drop down menu
of the window that pops up and then “Accept”.
d. Choose the “Conf” tab.
e. Set “PW90 – 90deg pulse [s]” to the previously determined 90° pulse
width.
f. Click on the “Main par” tab and then set the Relaxation Field to 25 MHz,
the Maximum T1 to 0.2 s, Recycle Delay to 0.2 s and the Maximum Scans
to 1. Use a longer value for the times if the T1 is significantly longer than
0.1 s.
g. Click on the gun icon (top left corner of screen) to acquire the data.
h. Click on the save icon (icon of a floppy disk – same as in Microsoft
Office).
i. Click on the evaluation dialogue icon (icon is a box with 12 in it on the top
left tool bar on screen).
j. Choose “RAM: Relax rate using WAM” from the window that pops up
and then choose “Execute”.
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k. The display graph on the right will show the T1 relaxation curve, and the
actual T1 value will be displayed in the left report panel under the
“Report” tab.
l. Click on the correct T1 icon (icon of a bulls-eye with “T1” over it).
m. Repeat the T1 correction (steps g to l) until a good T1 curve is obtained
(The measurement curve should extend out in time until the data begin to
flatten at the top) in the display and further repetition of this measurement
would not show significant differences. (Note: when you use the T1
correction button, the software is optimizing experimental parameters such
as the Polarization and Recycle times based on the measured T1. This is
why it is a good idea to iterate this measurement.)
n. Record the T1 value at the relaxation field used (usually 4MHz).
o. Choose the “Main” tab
p. Click on the “Relaxation field” box and enter a value, usually 10MHz.
q. Repeat steps g to l to obtain the T1 value at this new relaxation field.
(Note: The T1 correction in steps k and l should not be necessary at this
point.)
r. Repeat steps o to q in order to obtain the T1 values at 20, 30, and 40Mhz
(entered in step p). This will provide enough T1 values to allow
estimation of the maximum polarization time and the recycle delay.
Typically, T1 increases with field, so only an estimate of T1 at 35 or 40
MHz is necessary to estimate the maximum T1 and corresponding
polarization and recycle times.
8) Collecting a NMRD Profile.
a. From the “Actions” pull-down menu (top left corner of the screen), choose
“Profile Wizard”.
b. In the window that pops up, click on “Synchronize with Acq Parameters”
(bottom left corner of window). This uses the last known T1 to set up the
initial acquisition parameter to measure T1 starting at the highest field
specified by the user in the profile wizard.
c. Check the following parameters (list on right side of window) and type in
the correct values, if needed. (Do not hit return after typing in a field as
this will start data acquisition.)
i. MaxVRLX: [maximum field strength – usually 40 or 35]
ii. Polar. Time TPOL: [3 to 4 times maximum T1]
iii. Recycle Delay RD: [same as Polarization Time TPOL]
iv. Initial T1MX: [approximate T1 at maximum or initial field
strength]
d. Change the data filename and location (click on button).
e. Choose the “Settings” tab (left side of window) and confirm the following
settings:
i. T1MX tolerance range [%]: 3 to 5%
ii. F1 tolerance range [Hz]: 10000
f. Click on “Execute”.
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g. The Profile Wizard will begin the experiment by testing the entered value
of the maximum T1 at the highest field strength. If the entered value is
too different from the initial measurement, a window will be displayed
that displays the used and found values of T1, and states “The discrepancy
is out of tolerance! Recommended action: Try again”. Click on “Try
Again” (bottom right corner of window) to continue the experiment. The
Profile Wizard will continue testing T1 until the difference of two values
in a row are obtained that are within the tolerance range. At this point, the
window will no longer say “The discrepancy is out of tolerance!”, but will
state that T1 is within tolerance. The “Try Again” button will change to
“Continue”. Click on “Continue”, and the Profile Wizard will proceed to
automatically collect all points in the T1 profile.
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SOP for Shut Down of the Spinmaster Relaxometer
1) Switch off the transmitter by pushing the green button
labeled “TX” on the PC-NMR console. (The PCNMR console is the box sitting on top of the
relaxometer shown in Figure 9.)
2) Turn off the relaxometer by pressing the “OFF”
button (red button) on the middle box inside the left
cabinet. (See middle panel shown in Figure 10.)
Figure 9 PC-NMR Console
Note the orange and
green switch locations.
3) Turn off the pump by pressing the “PUMP OFF” button (yellow button on bottom
box). You should hear the pump switch off. (See
lower panel shown in Figure 10.)
4) Turn off the relaxometer (black switch on bottom
panel inside the left cabinet of relaxometer – see
Figure 10.)
5) Turn off the temperature control unit (black switch
on top box on the VTC which is inside and at the
top of the left cabinet of relaxometer – see Figure
10.)
Figure 10 From Top to
Bottom: VTC Unit, Power
Supply Control and Magnet
Cooling Pump
6) Turn off the NMR console by pressing the orange
button labeled “COMPUTER” (PC-NMR box on top of the relaxometer (see
Figure 9). This will initiate a Windows shut down on the computer.
7) Turn off the breaker (on the back of the relaxometer).
8) Turn off the tap water and disconnect the hose from the tap, reconnecting the two
ends of the hose so that the water doesn’t run out of the hoses onto the floor.
9) Turn off the compressor (located in the gradient cabinet room in the 3T MRI
suite) by turning the red switch to off. Make sure a plastic container is under the
drain valve under the compressor. Slowly open the black valve on the bottom of
the compressor to de-pressurize and drain the condensate.
8