Hello,<br>I want to measure the volume of my groups&#39; cortex, n=139, mostly males.  I am using fs 3.0.5.<br><br>From the aseg.stats file, lh + rh white matter is 548,000 and gray matter is 487,000, for a ratio of 1.1.  I know the aseg.stats file is not a good place to go for gray matter volume, as it is usually underestimated.  <br>

<br>Looking in the aparc.a2005.stats file, the average white matter is 606,000 and gray matter is 463,000, for a ratio of 1.3.<br><br>I was surprised the gray matter actually went down, and the ratio of 1.3 seems a bit high.  Is this normal?  I see in the aseg.stats file, skin left over after the watershed is counted as cortex and so is a fair amount around the cerebellum.  Could partial volumeing also be a possible explanation?  I would think that the aparc file would be most accurate, but with these results, I wanted to doublecheck.<br>

<br>Thanks Bruce for answering my earlier question.  I am still looking at the pallidum differences and will let you know soon.<br><br>Thanks!<br>Jeff Sadino<br>