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Thanks for the reply Dr Greve!

I have inserted responses to your questions below. I do hope it makes more sense this time thanks for bearing with me.

Cheers, Todd Sheckley, EODCS, USN Ret. ________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@mgh.harvard.edu Sent: Thursday, December 6, 2018 11:07 AM To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Help with Data

On 12/04/2018 02:17 PM, T and LS wrote:

    External Email - Use Caution

Dear Help Desk - I have a few basic questions about freesurfer. I am retired military bomb technician working on a blast TBI initiative and not a research so please bear with me. We are looking at a long term study of bomb technicians and I am curious about the following before moving forward.

1. Total number of images processed by freesurver? Is this in the thousands or millions?

Do you mean since FS was created? Probably around 100,000 by now. ​Yes thanks.

1. Cohart group data is this from each organization or is there a central pool. e.g. I had a 3D volumetric MRI done with DTI at Washington University in St Louis and am 49yrs old is this only from their pool or larger data base? Any idea number of images in that data base?

I'm not sure what you mean. Can you elaborate? You cannot use DTI as input to freesurfer. Are you talking about the Human Connectome Project (HCP) data from Wash U?

​DTI was processed separately from 3D MRI. What I am trying to establish since DOD/VA do not use FS that much is there a way for them to tap into a database of cohart brain scans so they do not have to start from scratch or are the individual databases all proprietary.

No this would be a new long term study of US Military Explosive Ordnance Disposal (EOD) Technicians and currently we are leaning towards the new DVBIC site being established on Eglin AFB in Florida, since that is where all DOD EOD Techs go to school.

1. Standard Deviations, Patient Annual Volume Change and Group Annual Volume change; are these organizations specific or a larger data base.

I'mnot sure what you mean. Are you asking if we have such a data base?

See attached example that was charted from 3T machine. Are the items within my question above all specifically developed at Washington University or is there a main database that the project we are trying to establish for long term research on the brains of military bomb techs.

1. How accurate are the volumes from a 3T MRI and is there a huge fluctuation if scans are done on the same exact MRI system? e.g. in my scan some of the thicknesses were down to .0013mm and volumes down to .9mm3 = is there a lot of error in those numbers.

The actual values are not accurate downto that level. It is hard to say what the accuracy really is but probably worse than 3%.

See attached example they list loss for patient and average loss for age group on a annual basis.

Thanks for any information you can provide! It seems there will be a DVBIC site open soon where our school is and I would like to be able to provide some input on this.

Thanks, Todd Sheckley

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