Hi Hiquing,<br><br>It seems that the first table was created by a program not provided from us??<br>The second table seems to be created from the software obtained from Kriby Center in KKI?<br><br>Anyway, I can give some generic information.<br>
<br>1) In Philips, you can specify the order of 32+1 images. I believe the default is b0 + 32 DWIs + calculated isotropically weighted image. You can also choose to store 32 DWIs + b0 + calculated.<br><br>This is one reason of the difference<br>
<br>2) In DtiStudio, we use "100, 100, 100" to exclude images you don't need. That is why the second table has 34 rows and the final raw is "100, 100, 100". Apparently, the second table was created specifically for DtiStudio. The first table has only 33 rows because it ignored the last image.<br>
<br>This is the second reason of the difference.<br><br>3) Philips has two options of gradient tables; with and without gradient overplus. If this option is "on", the table is designed to always use at least 2 gradients. In this way, you can maximize the b-value efficiency and shorten the echo time (thus higher SNR). Apparently the first table is "off", because there is "1, 0, 0". The second is "on".<br>
<br>This is the third reason of the difference.<br><br>Hope this clarify the question. You need to know exactly what you did for the above three points and grab the correct table.<br><br>Susumu<br><br><div class="gmail_quote">
2010/9/14 黄海清 <span dir="ltr"><<a href="mailto:basketballmouse@163.com">basketballmouse@163.com</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hi,<br><br>I'm dealing with DTI data from Philips Achieva 3T. I tried two methods to compute the gradient table (32+1).<br>(1) " dcm2nii.exe " with Philips dicom files<br> 0 0 0<br> 1.0000 0 0<br>
0 -1.0000 0<br> 0 0 -1.0000<br> -0.0424 0.1146 0.9925<br> 0.1749 0.2005 0.9640<br> 0.2323 0.1626 0.9590<br> 0.3675 -0.0261 0.9296<br> 0.1902 -0.3744 0.9076<br>
-0.1168 -0.8334 0.5402<br> -0.2005 -0.2527 0.9465<br> -0.4958 -0.1345 0.8580<br> -0.0141 0.6281 0.7780<br> -0.7445 0.1477 0.6511<br> -0.7609 -0.3204 0.5643<br> -0.1809 -0.9247 0.3351<br>
-0.6796 0.4224 0.5997<br> 0.7771 -0.4707 0.4178<br> 0.9242 0.1036 0.3677<br> 0.4685 0.7674 0.4378<br> 0.8817 0.1893 0.4322<br> 0.6904 -0.7062 0.1569<br> 0.2391 -0.7571 0.6080<br>
-0.0578 -0.9837 -0.1703<br> -0.5368 -0.8361 0.1135<br> -0.9918 0.1207 0.0423<br> -0.9968 -0.0709 0.0379<br> -0.8724 -0.4781 0.1014<br> -0.2487 -0.9336 -0.2581<br> 0.1183 -0.9919 0.0471<br>
0.3376 -0.8415 -0.4218<br> 0.5286 -0.8409 -0.1163<br> 0.9969 -0.0550 0.0571<br>(2) " DTI_gradient_table_creator_Philips_RelX.m " with Philips par/rec files<br> -0.6533 -0.2706 -0.7071<br>
-0.2087 -0.6756 -0.7071<br> 0.0197 -0.7068 -0.7071<br> 0.4212 -0.5679 -0.7071<br> 0.6899 -0.1549 -0.7071<br> -0.6535 -0.2707 -0.7069<br> -0.5000 -0.5000 -0.7071<br> -0.2929 -0.7071 -0.6436<br>
0.2945 -0.7064 -0.6436<br> 0.5150 -0.4861 -0.7061<br> 0.7071 -0.2929 -0.6436<br> -0.7071 -0.4725 -0.5261<br> -0.4725 -0.7071 -0.5261<br> 0.5555 -0.6439 -0.5261<br> 0.7071 -0.4725 -0.5261<br>
-0.7071 -0.7071 -0.0002<br> 0.7071 -0.7071 0<br> -0.7071 -0.4725 0.5261<br> 0.7071 -0.4725 0.5261<br> 0.4725 -0.7071 0.5261<br> 0.7071 -0.4725 0.5261<br> -0.6364 -0.4252 0.6436<br>
-0.7060 -0.7060 0.0547<br> -0.2929 -0.7071 0.6436<br> 0.2929 -0.7071 0.6436<br> 0.7071 -0.7071 0.0078<br> 0.7071 -0.2929 0.6436<br> -0.5847 -0.3977 0.7071<br> -0.7063 -0.7063 0.0489<br>
0.0347 -0.7063 0.7071<br> 0.7071 -0.7071 0.0115<br> 0.7071 0 0.7071<br> 0 0 0<br> 100.0000 100.0000 100.0000<br>They seem totally different. So can any person explain this problem? Thank you very much!<br>
<br>Haiqing<br><br><br><span title="neteasefooter"><span><hr>
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