Thanks a lot!<div><br></div><div>SC<br><br><div class="gmail_quote">2009/4/8 susumu <span dir="ltr"><<a href="mailto:susumu@mri.jhu.edu">susumu@mri.jhu.edu</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>
<div dir="ltr" align="left"><font face="Arial" color="#0000ff" size="2"><span>Here it is.</span></font></div><br>
<div lang="en-us" dir="ltr" align="left">
<hr>
<font face="Tahoma" size="2"><b>From:</b> <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>
[mailto:<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] <b>On Behalf Of
</b>[Seongjin]<br><b>Sent:</b> Tuesday, April 07, 2009 10:31 PM<div class="im"><br><b>To:</b>
DTI Studio, ROI Editor, Landmarker Questions/Support<br></div><b>Subject:</b>
[Mristudio-users] Re: re： How to do a Tailarach
transformation?<br></font><br></div><div><div></div><div class="h5">
<div></div>Dear Susumu,<br><br>Do you have relevant literature on your
opinion:<br><br>"...<font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">In reality, within
practical imaging time, I don’t think you can observe such effect clearly. Our
past measurement (Landman et al, NeuroImage) suggests once you have
12-orientation or more, you don’t see much
differences..."</span></font><br><br>If you had, could you share the
literature?<br><br>Thanks.<br><br>- SC<br><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"><br>
</span></font><br>
<div class="gmail_quote">2009/4/7 susumu <span dir="ltr"><<a href="mailto:susumu@mri.jhu.edu" target="_blank">susumu@mri.jhu.edu</a>></span><br>
<blockquote class="gmail_quote" style="padding-left:1ex;margin:0pt 0pt 0pt 0.8ex;border-left:rgb(204,204,204) 1px solid">
<div lang="EN-US" vlink="blue" link="blue">
<div>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">Hi
Jinsong,</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">It depends on whom
you ask the question, but here is my opinion.</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">When you are using
diffusion “tensor” imaging, all data will be fitted to obtain only the 6
tensor elements. Therefore, you need only 6 directions mathematically.
However, such measurement takes only less than 1 min and do not have enough
SNR (signal-to-noise ratio). To enhance the SNR, you need to acquire more
data.</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">Usually people spend
4-10 min of time for DTI, in which you can acquire about 30 – 100 images. Then
you have several options. For example, you can repeat the 6-orientation
measurement 5 times (total 30) or one 30-orientation measurement within the
same amount of time (should be within 5 min). </span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">Purely from
mathematical point of views, I don’t think 6-direction x 5 vs 30-orientation
have that much difference in terms of overall SNR. However, it is true that
the 6-orientation measurement has more orientation-dependent inhomogeneity in
SNR. This means, certain orientations can be measured with higher SNR while
some orientation has poorer SNR. By adopting more orientations, such
orientation-dependent SNR profile becomes more homogeneous (less orientation
dependent).</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">In reality, within
practical imaging time, I don’t think you can observe such effect clearly. Our
past measurement (Landman et al, NeuroImage) suggests once you have
12-orientation or more, you don’t see much differences.</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">Some researchers are
seeking for diffusion “more than one tensor” imaging. If you want it, you may
need more than 30 orientations and higher b-values. So, you may need to design
very different protocols.</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial">Susumu</span></font></p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<p><font face="Arial" color="navy" size="2"><span style="font-size:10pt;color:navy;font-family:Arial"></span></font> </p>
<div>
<div style="text-align:center" align="center"><font face="Times New Roman" size="3"><span style="font-size:12pt">
<hr align="center" width="100%" size="2">
</span></font></div>
<p><b><font face="Tahoma" size="2"><span style="font-weight:bold;font-size:10pt;font-family:Tahoma">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size:10pt;font-family:Tahoma"> <a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a> [mailto:<a href="mailto:mristudio-users-bounces@mristudio.org" target="_blank">mristudio-users-bounces@mristudio.org</a>] <b><span style="font-weight:bold">On Behalf Of </span></b>jinsong tang<br>
<b><span style="font-weight:bold">Sent:</span></b> Tuesday, April 07, 2009 12:52
PM<br><b><span style="font-weight:bold">To:</span></b> DTI Studio, ROI
Editor, Landmarker Questions/Support<br><b><span style="font-weight:bold">Subject:</span></b> [Mristudio-users]
re</span></font><font face="MS Mincho" size="2"><span lang="JA" style="font-size:10pt;font-family:'MS Mincho'">：</span></font><font face="Tahoma" size="2"><span style="font-size:10pt;font-family:Tahoma"> How to
do a Tailarach transformation?</span></font></p></div>
<div>
<div></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p>
<div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt">Hello
everyone,</span></font></p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt">Now the
Siemens 3.0 T MRI scanner can collect </span></font>30
non-collinear directions diffusion data. Does this helpful for
fiber tracking ?</p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt">But I
found most paper only use 12 directions. Does anybody know
why?</span></font></p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt">Best,</span></font></p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p></div>
<div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt">Jinsong</span></font></p></div></div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"></span></font> </p>
<div style="text-align:center" align="center"><font face="Times New Roman" size="3"><span style="font-size:12pt">
<hr align="center" width="100%" size="1">
</span></font></div>
<p><font face="Times New Roman" size="3"><span style="font-size:12pt"><a href="http://cn.rd.yahoo.com/mail_cn/tagline/card/*http:/card.mail.cn.yahoo.com/" target="_blank"><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">好玩</span></font><font face="SimSun"><span lang="JA" style="font-family:SimSun">贺</span></font><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">卡等你</span></font><font face="SimSun"><span lang="JA" style="font-family:SimSun">发</span></font><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">，</span></font><font face="SimSun"><span lang="JA" style="font-family:SimSun">邮</span></font><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">箱</span></font><font face="SimSun"><span lang="JA" style="font-family:SimSun">贺</span></font><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">卡全新上</span></font><font face="SimSun"><span lang="JA" style="font-family:SimSun">线</span></font><font face="MS Mincho"><span lang="JA" style="font-family:'MS Mincho'">！</span></font></a></span></font></p>
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