Hi Matt,
We need the in-plane resolution to be high but sacrificing a bit on
the thru plane. Averaging directions before ECC is a good idea. I'll
try it out. Thanks!
Mike
On Sep 18, 2009, at 5:03 PM, Matt Glasser wrote:
> With 4mm slices you will have huge partial voluming in the slice
> orientation, what are you trying to do with this data? I would
> register
> your like (i.e. all repetitions of direction 1) gradient
> orientations and
> average them before trying to do eddy current correction if you have
> low
> SNR.
>
> Peace,
>
> Matt.
>
> -----Original Message-----
> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On
> Behalf
> Of Mike Yassa
> Sent: Friday, September 18, 2009 6:54 PM
> To: [log in to unmask]
> Subject: Re: [FSL] volume corruption
>
> Hi Matt,
> Can't do 2mm. We're trying to get sub-mm resolution to look at very
> small regions. The b value is 1200 on a 3T magnet. I take lots of
> averages to get better SNR. The same data worked well for many other
> subjects. Is it likely that motion in these few subjects caused this
> problem?
>
> Thanks
>
> Mike
>
> On Sep 18, 2009, at 4:08 PM, Matt Glasser wrote:
>
>> That data is probably of too poor quality for the registrations to
>> work
>> well. I recommend you try 2mm isotropic data, however that SNR
>> still seems
>> too low to me. Are you using a 1.5T magnet and/or a high b value?
>>
>> Peace,
>>
>> Matt.
>>
>> -----Original Message-----
>> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On
>> Behalf
>> Of Mike Yassa
>> Sent: Friday, September 18, 2009 4:59 PM
>> To: [log in to unmask]
>> Subject: Re: [FSL] volume corruption
>>
>> Hi Matt,
>>
>> Attached is a picture of the pre-ECC volume. Post ECC is blank as you
>> saw in the previous email. The sequence is 0.8 x 0.8 x 4mm coronal
>> with 32 directions. The data's dimensions are 256 x 256 x 15 x 34.
>> Because of the high resolution they are very noisy, but that's not
>> the
>> problem.
>>
>> Any ideas?
>>
>> Thanks!
>>
>> Mike
>>
>
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