I think cross-scanner normalization is a very tricky issue. It is always related to your effect size. If you are following a stroke patients and Warrarian degeneration causes 50% FA change, then you can just scan a couple of subjects in both scanners and show the maximum difference could be only within 10%. I think this is a valid logic. However, if you can't do a comparison study like this (e.g. one of the scanners is out of commission) and you are going after 5% effect size, then you have a very tough case, especially for publication.<br>
<br><div class="gmail_quote">On Fri, Feb 3, 2012 at 8:00 AM, Lucas Lessa <span dir="ltr"><<a href="mailto:lucas_lessa@yahoo.com.br">lucas_lessa@yahoo.com.br</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear friends,<br>
<br>
I'm trying to compare the changes in DTI in a case.<br>
I have several studies from one subject, all of them have DTI, but I can't observe changes, probably because of the differences in the studies.<br>
Some studies were made in Philips Achieva 1,5T and other in a GE HD 1,5T.<br>
The good thing is that all studies have 33 directions.<br>
But it's the only similarity.<br>
Can I normalize these studies?<br>
Thank you.<br>
<font color="#888888"><br>
Lucas Lessa.<br>
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