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Comment by devereaux | Hacker News Reader

With a usual CT scan, you can do a volume rendering. Play around with the opacity to show the skin - this will give you a 3D image of your face.

Example on http://1.bp.blogspot.com/-LuLV6F-Fp0o/TbcY7BUvpjI/AAAAAAAAAM...

With a usual MRI, unfortunately slices are too far apart to be able to stitch them together like this.

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I did a volume rendering on MRI data of my brain a few years ago: https://www.facebook.com/joshenders/videos/10153821500755252...

All the MRI scans of my brain I've gotten ("structural" scans taken as part of fMRI studies) have been sufficient to get a pretty decent volume rendering of my head. Some of them cut off about half way through the jaw, but that's another issue entirely.

The research scans use 3D T1 (and sometimes T2) scans for mapping the functional data onto a brain region. They have to put the low res functional scans onto something that has some degree of resolution. Functional scans are acquired with temporal resolution in mind - the change in signal after activation is something like 6 seconds, and to accurately sample this you want a whole brain acquisition in much less time that that. We typically acquire whole brain scans in something like 3 seconds. New techniques such as multiband imaging are acquiring whole brain scans in 600-700ms or so. This is pretty fast. Clinical scans do use 3D techniques but tend to go for 2D scans (which are a slice, then a gap of 10-30% usually of slice thickness) then a slice. 2D scans are faster, have much better in plane resolution (lower through plane as slices are fatter and have gaps between them). Clinical scans are also one hell of a lot better for identifying things as numerous image weighting a are obtained. MR tech here.

What's the resolution of the whole brain scan you deal with in research these day? (ie the cubic size of the voxel when acquired in 3s? What about in 600ms)

I have to keep myself up-to-date, it's been a while since I played with that!

I'll check - I'd guess 3mm slices but with 600ms acquisitions I haven't looked recently enough to remember.

I have files from a CT scan, perhaps I'll look into this.

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