[Mne_analysis] FLASH sequence for BEM

[Jon Houck]

Thanks all!  I appreciate the feedback.  A memory upgrade would be nice but
is not likely in the near future.  The 5-echo FLASH sequence is working
fine for me on the Trio.  The surfaces look good and are nearly identical
with either 8 or 5 echoes.

Jon



On Thu, Oct 9, 2014 at 5:35 PM, Eric Larson <larson.eric.d at gmail.com> wrote:

> I would verify that the BEM shell surfaces (inner/outer skull and scalp)
> look decent e.g. in tkmedit. If they look good, then you should be okay. I
> *think* I have used Flash 5/30 sequences in the past with fewer than 8
> echoes without any problems.
>
> Eric
>
>
> On Thu, Oct 9, 2014 at 2:53 PM, dgw <dgwakeman at gmail.com> wrote:
>
>> Hi Jon,
>>
>> If your results look comparable, then there shouldn't be a problem.
>> The crashing problem can be fixed by adding more RAM to the console
>> computer.
>>
>> HTH,
>> D
>>
>> On Thu, Oct 9, 2014 at 3:07 PM, Jon Houck <jhouck at unm.edu> wrote:
>> > Hi all,
>> >
>> > I've been using FLASH sequences based on the 5- and 30-degree FLASH
>> from MGH
>> > (http://www.nmr.mgh.harvard.edu/~andre/MGH_Morphometry_3T.pdf) with the
>> > Siemens 32-channel head coil.  Image reconstruction fails for this
>> sequence
>> > on a fairly regular basis, possibly due to the additional data (8
>> echoes x
>> > 32 channels) overwhelming the MR acquisition computer.  As far as I can
>> tell
>> > remote reconstruction is only an option for EPI sequences.
>> >
>> > The simplest option might be dropping a few echoes from the sequence.
>> When
>> > I do this the inner skull surface produced by a slightly-modified
>> > mne_flash_bem looks comparable for 8 echoes and for 5 echoes (i.e., the
>> > echoes at 11.85, 13,85, and 15.85 ms were dropped).  I've only been
>> able to
>> > test this on a couple of subjects.  Has anyone done something similar or
>> > anticipate any problems with BEM construction using this approach?
>> >
>> > Thanks,
>> >
>> > Jon
>> >
>> >
>> >
>> >
>> >
>> >
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