<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV>Hi Dr. Mori,</DIV>
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<DIV>I have a question to your response. The fiber density (fiber count/voxel) is usually more than 1, so many line propagations or fibers will go through the same voxels. When DTI Studio calculates mean FA for a reconstructed fiber tract, does it calculate based on all voxels in the fiber tract with each voxel appear once or based on fibers so that voxels belong to multiple fibers will be appear multiple times?<BR></DIV>
<DIV>Thanks,</DIV>
<DIV>Jun Yi</DIV>
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<B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> susumu <susumu@mri.jhu.edu><BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> "DTI Studio, ROI Editor, Landmarker Questions/Support" <mristudio-users@mristudio.org><BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Wednesday, December 3, 2008 3:36:46 PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [Mristudio-users] ImgVal Calculation<BR></FONT><BR>
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<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">This is an interesting observation. It should be a simple binary masking. The pixel with fibers are 1 and other pixels are 0. We multiply this masking to loaded images and calculate average and STD. Do you think our values are off? If so, this is definitely something we should look into. Could you send us (not by MailingList) one fiber file and a co-registered FA map?</SPAN></FONT></P>
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<P class=MsoNormal><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"> mristudio-users-bounces@mristudio.org [mailto:mristudio-users-bounces@mristudio.org] <B><SPAN style="FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Hui Jing Yu<BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Friday, November 21, 2008 1:56 PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> mristudio-users@mristudio.org<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> [Mristudio-users] ImgVal Calculation</SPAN></FONT><FONT face="Times New Roman" size=3><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman'"></SPAN></FONT></P></DIV>
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<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt">Dear DTI Studio users,</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt"> </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt">I have a question regarding the ImgVal calculation under statistical profile for fiber tracking. I got very different mean FA values (differences ranging from 0.04 to 0.1) when I tried these two methods (keeping all parameters consistent and same version of DTI):</SPAN></FONT></P>
<P class=msolistparagraph><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt"><SPAN>1.<FONT face="Times New Roman" size=1><SPAN style="FONT: 7pt 'Times New Roman'"> </SPAN></FONT></SPAN></SPAN></FONT>Load previously saved fiber track (binary) into DTI studio, click on fiber statistics and I have for Mean of ImgVal and Std. of ImgVal</P>
<P class=msolistparagraph><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt"><SPAN>2.<FONT face="Times New Roman" size=1><SPAN style="FONT: 7pt 'Times New Roman'"> </SPAN></FONT></SPAN></SPAN></FONT>Using MATLAB, apply the same binary fiber track onto FA image (analyze format), calculate mean/std values for all the pixels/voxels belonging to this fiber track</P>
<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt">How are these mean ImgVal calculated? I assume it is just a mean values for all the pixels/voxels that are contained in the fiber track of interest.</SPAN></FONT></P>
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<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt">Thanks in advance for your help.</SPAN></FONT></P>
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<P class=MsoNormal><FONT face=Calibri size=2><SPAN style="FONT-SIZE: 11pt">HJ</SPAN></FONT></P></DIV></DIV></DIV></div><br>
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