Hello Stacey,
this issue came up recently, please find attached some responses. I hope
this helps.
Cheers,
Jorge
On 21/03/2014 21:56, Stacey M Schaefer wrote:
Hello freesurfer gurus,
We acquire 2 BRAVO T1s on a GE 3T during the same scan session on most of our
study participants, but because of various issues, occasionally only get 1
T1/participant. I've been processing the data combining both T1s when we have 2
and using just 1 T1 when that was all we had thinking it would be best to use
the highest quality data as possible (more is better rational), especially
given the old FS recommendation that multiple acquisitions were better.
However, after perusing recent course materials, I came across the suggestion
in one of the powerpoints to always be consistent across subjects using either
1 or 2. Is that the most recent recommendation - if we don't have 2 acquisitons
on everyone to pick the one with best contrast and only use 1 T1/participant?
If so, can you explain why?
Thanks for your advice!
Stacey Schaefer
--
---------------------------------------------------
Stacey M. Schaefer, Ph.D.
Waisman Laboratory for Brain Imaging and Behavior
University of Wisconsin - Madison
1500 Highland Ave Rm T127
Madison, WI 53705
Waisman Phone: 608-263-9321
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Jorge Jovicich, Ph.D.
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Center for Mind Brain Sciences
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--- Begin Message ---
thanks Jorge,
nice to see that someone quantified this :)
Bruce
On Tue, 7 Jan 2014, Jorge
Jovicich wrote:
> Hi Hai,
>
> I agree with Bruce. In a recent paper
> (http://www.ncbi.nlm.nih.gov/pubmed/23668971), for a variety of 3T vendor and
> coil configurations, we confirmed previous findings that averaging two
> within-session uncorrupted MPRAGE scans did not significantly improve across
> session reproducibility. In you case just choose the best one of the two.
>
> Is it worth acquiring two MPRAGES then? Tricky. Maybe you can go for only a
> single acquistion if your MR operator is experienced to distinguish what
> level of artifact will be unacceptable for the target analysis and deserves a
> repeated acquisition in case of unacceptable quality. Otherwise, one may fix
> two acquisitions in the protocol and use the best of them. Nevertheless, the
> operators should always be paying attention to the data quality during the
> acquisition to decide if some type of intervention can help.
>
> cheers,
> jorge
>
> On 06/01/2014 21:38, Bruce Fischl wrote:
>> Hi Hai
>>
>> it really depends on your coil and field strength, and whether either is
>> motion-corrupted. For 3T 32 channel data our somewhat ad hoc opinion is
>> that one is better than two (due to blurring induced by interpolation),
>> but it's really a case-by-case decision.
>>
>> sorry that there isn't an easier answer
>> Bruce
>> On Mon, 6 Jan 2014, Hai Pan wrote:
>>
>>> Hello, FreeSurfer experts,
>>>
>>> We made two T1 scans for each subject at each session, will they be
>>> helpful
>>> for better recon-all results? Shall I average them and process the
>>> averaged
>>> T1 image? Let me know please.
>>>
>>> Thank you,
>>>
>>> Hai
>>>
>>>
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>
>
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