Dear sir
I have Airis I MRI system from Hitachi
it have a ghosts in the phase direction
any body guide me how to solve this or where as the problem
regards
This is very common problem that you describe. It's caused by system instability, usually in the magnetic field, but it can also be RF related. First rule out the possibility of vibration (including loose gradient coils, or a shaking table), then look at your eddy current compensation. RF reciever calibrations (SSB suppression, I think you have an analog RF system) can also give bad phase direction artifacts. Magnetic disturbance at 60 Hz can also give ghosting--you can run the tests late at night to see if it gets better.
Hello,
There are not too much information to investigate your problem. As Steven described there are many reasons for "ghosting". Is it new installed systems or it is used for a time? What sequeces are affected? Would you like to send a typical problematic image? Send it to email
my private e-mail is osamaakkash@yahoo.com
its an old system was worked normally
the sequence mostly in when get t2 with a tin slices
and some time on t1
mostly see it in sequence number one and its less on sequence 3
There is no substitute for having an experienced MRI guy on site and doing the Hitachi tests.
I know that you're struggling with this, but terms like 'sequence 3' are not meaningful to anyone else.
In general, gradient echo sequences will have worse ghosting than spin echo sequences. If that's what you see, then it's quite likely a magnetic field disturbance (either vibration, 60 Hz magnetic noise, or eddy current comp). That's because the SE sequences have an additional refocussing pulse that the GE sequences lack.
If the SE sequnces have ghosting also, especially the T2 and thin slices, it may be that the reduced S/N of these sequences is making the ghosting appear worse than the other sequences.
Run the Hitachi tests and get quantitative data, and compare to the manufacturer's specifications. Make sure that the other system specs are OK. Is the room temperature well controlled?
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M.O.A.
ghosts in the phase direction
October 30, 2012 10:09
Dear sir
I have Airis I MRI system from Hitachi
it have a ghosts in the phase direction
any body guide me how to solve this or where as the problem
regards
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Mahmood ElHoor
re: ghosts in the phase direction
November 03, 2012 11:01
Where are you from?
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Steven Ford
re: ghosts in the phase direction
November 05, 2012 05:20
This is very common problem that you describe. It's caused by system instability, usually in the magnetic field, but it can also be RF related. First rule out the possibility of vibration (including loose gradient coils, or a shaking table), then look at your eddy current compensation. RF reciever calibrations (SSB suppression, I think you have an analog RF system) can also give bad phase direction artifacts. Magnetic disturbance at 60 Hz can also give ghosting--you can run the tests late at night to see if it gets better.
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M.O.A.
re: re: ghosts in the phase direction
November 06, 2012 08:53
many thanks for your reach-full answer
yes I have an analog RF system
but suppose the problem is 60Hz disturbance what the solution for it
regards
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Mahmood ElHoor
re: re: re: ghosts in the phase direction
November 06, 2012 05:25
Hi Osama, it is never from 60 Hz, I think you have 50 Hz system.
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Wojciech Selwesiuk
re: ghosts in the phase direction
November 05, 2012 06:08
Hello,
There are not too much information to investigate your problem. As Steven described there are many reasons for "ghosting". Is it new installed systems or it is used for a time? What sequeces are affected? Would you like to send a typical problematic image? Send it to email
to rate and post a comment
M.O.A.
re: re: ghosts in the phase direction
November 06, 2012 08:53
my private e-mail is osamaakkash@yahoo.com
its an old system was worked normally
the sequence mostly in when get t2 with a tin slices
and some time on t1
mostly see it in sequence number one and its less on sequence 3
to rate and post a comment
Steven Ford
re: re: re: ghosts in the phase direction
November 06, 2012 11:40
There is no substitute for having an experienced MRI guy on site and doing the Hitachi tests.
I know that you're struggling with this, but terms like 'sequence 3' are not meaningful to anyone else.
In general, gradient echo sequences will have worse ghosting than spin echo sequences. If that's what you see, then it's quite likely a magnetic field disturbance (either vibration, 60 Hz magnetic noise, or eddy current comp). That's because the SE sequences have an additional refocussing pulse that the GE sequences lack.
If the SE sequnces have ghosting also, especially the T2 and thin slices, it may be that the reduced S/N of these sequences is making the ghosting appear worse than the other sequences.
Run the Hitachi tests and get quantitative data, and compare to the manufacturer's specifications. Make sure that the other system specs are OK. Is the room temperature well controlled?
to rate and post a comment