Large Scanner Setups
Scanners designed for humans and used for non-human primate (NHP) and large animals
(pigs) are normally 3T and 7T large bore scanners. Large scanners are enclosed and do not
have direct access to the MRI GND. Engineers are averse to providing access to GND lines that
are accessible from the power and control room.
Small Scanners
Scanners designed for small NHP and rodents. These scanners are high
fi
eld scanners
designed for specialized measurements in rodent, small mammal and small NHP such as
marmosets. They range in power from 4.7 to 16.8 T and the bore diameter is on the order of a
10-20 centimeters. These scanners will often have built in shields and may have easy access
to the MRI GND. The GND should be on the MRI or in the gradient supply in the nearby
component room.
Vertical Scanners
Some NHP groups have vertical Brukner 4.7 and 9.4 T scanners. These scanners present a
signi
fi
cant problem when attempting to place the PZ5 / PZA Subject Interface ampli
fi
er at a
distance from the scanner. In this case the the preamp should be as far away from the gauss
fi
eld of the magnetic (>50 gauss). If possible, connect the GND of the MRI to the GND on the
RF
fi
lter.
Testing
Minimizing Imaging Artifacts
The
fi
rst step is to verify that the neural recording system introduces minimal image artifact.
To do this:
Setup an agar gel or saline phantom with the headstage and electrodes to image the
baseline noise. Verify RF noise is minimal and there is no
fi
eld distortion.
Example
fi
eld maps (measure of signal distortion) and real images for ferrous and non-
ferrous headstage/electrodes are shown below.
1.
fMRI User Guide | 24
