MRI setup & programming
Varian 9.4T MRI Tips
EPI optimization
Shim volume should be inside the brain & away from the ear canal
Always use R-L as readout direction
Use ramp sampling to reduce echo train length
Data size limit
Maximum FID file size is 2GB
Which means for 10 slices of 256x256 image, you can only acquire < 410 repetitions (using single channel) or < 103 repetitions (using 4 channel).
If exceed, the scanner will run but no data will be saved! Have to calculate your data size if you plan to scan high-res and many repetitions.
Bruker Biospec 9.4T MRI Tips
EPI optimization by MAPSHIM
Load Field Map protocol and run MAPSHIM macro to acquire field map.
Load PRESS protocol and use it to select the voxel for localized shim.
Run MAPSHIM with "Local" option.
Make new sequence
run /opt/PV5.1/bin/CopyMethod
make install clean cproto
copy *.ppg/*.mod files to /opt/PV5.1/exp/stan/nmr/lists/pp
restart PV to see the new sequence
Artifact
Dark bad in spin-echo:
cause: mismatched excitation and refocusing RF pulse bandwidth
solution: reduce exc bandwidth to make refoc bandwidth at 10-20% wider
"Motion" in phase-encoding direction of EPI
cause: frequency drift due to gradient heating
solution: reduce duty cycle by increasing TR or reducing number of slice
Bruker ClinScan 7T Tips
Orientation
Choose Head First, Supine to ensure the displayed orientation is like what it should be.
Optimize shimming for EPI
Display Adjustment volume (View->Adjustment volume) and reposition inside the ROI (eg, brain).
Choose Advanced shim mode in Sequence->Adjustment.
When "frequency adjustment doesn't converge"...
unplug and replug the coil connector
may need to do it a few times
Debug log files
Data, HostInstLog, HostLog, MRIRLog
Siemens 3T MRI Tips
Online manual
IDEA programming Tips
Install sequence
copy *.dll & *.i86 to \MedComm\MriCustomer\seq (on host)
Gradient system
ClinScan: 7TZ
Trio: TQ-engine
Change gradient setting in IDEA: type 'gradconf -h' to see detail.
External RF file
\n4\MriSitedata\7TZ (or TQ-engine for Trio) (in IDEA)
\MedComm\MriSitedata\measurement (on host)
perform PAS unload in ideacmdtool every time you add an RF file
External gradient table for DTI
\n4\x86\prod\bin (in IDEA)
\MedComm\MriCustomer\seq (on host)
Get k-space data
open start menu by CTRL+ESC
Programs->Save Meas Data
look for data based on date/time
Option->copy from RAID
k-sapce data will be saved as meas.dat