Hi Lilla

we have a large dataset already processed with FSv5.1; before processing it with FSv6, we thought to assess -on a smaller subset - how significant are the differences between the measurements output by the two versions.

On the other point, my question was about differences between the two versions in relating volume with number of voxels. I can see that in FS5, the volume has the same value as the number of voxels, whereas this does not hold in FS6. So I was wondering the reasons behind that.

thank you gianluca

On 13 Dec 2017, at 19:24, Lilla Zollei lzollei@nmr.mgh.harvard.edu wrote:

Hi Gianluca,

...

I am working with data coming from two different versions of Freesurfer, v5.1 and v6. As measurements looks different (an excerpt below from aseg.stats files), I am trying to see if that difference is statistically relevant. Could you anticipate something with this respect?

We do not advise you to include data processed with different versions in the same study as there are differences between our releases.

...

One more question is about voxel counting and their volume. aseg.stats prints out that # VoxelVolume_mm3 1 but volumes from v.6 seems to be sometimes greater sometimes lower than the voxel number, while in v. 5.1 they correspond. Could you give me some clarification?

I do not understand your question. Are you asking about the volume differences between the two versions?

Lilla

...

v.6

# ColHeaders Index SegId NVoxels Volume_mm3 StructName normMean normStdDev normMin normMax normRange 1 4 5424 5779.6 Left-Lateral-Ventricle 22.1768 15.6303 0.0000 81.0000 81.0000 2 5 198 225.9 Left-Inf-Lat-Vent 43.8838 14.0865 6.0000 77.0000 71.0000 3 7 17444 18248.8 Left-Cerebellum-White-Matter 80.5691 8.7322 20.0000 133.0000 113.0000 4 8 69258 69340.7 Left-Cerebellum-Cortex 49.2701 12.9332 0.0000 128.0000 128.0000 5 10 8758 8432.7 Left-Thalamus-Proper 81.4639 10.8500 37.0000 123.0000 86.0000

v. 5.1

# ColHeaders Index SegId NVoxels Volume_mm3 StructName normMean normStdDev normMin normMax normRange 1 4 5013 5013.0 Left-Lateral-Ventricle 16.7825 16.6860 0.0000 82.0000 82.0000 2 5 161 161.0 Left-Inf-Lat-Vent 39.9084 12.2446 7.0000 73.0000 66.0000 3 7 19250 19250.0 Left-Cerebellum-White-Matter 83.1263 8.1640 41.0000 110.0000 69.0000 4 8 60246 60246.0 Left-Cerebellum-Cortex 50.8222 10.7915 5.0000 93.0000 88.0000 5 10 7911 7911.0 Left-Thalamus-Proper 88.1600 10.4226 43.0000 134.0000 91.0000

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