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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I agree with Susumo however there are some differences
between vendors<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>We have similar GE system and I am sure that TR=17s is quite
long for 33 directions and 50 slices.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Are you using 128x128 matrix? Asset On? optimal TE?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>These systems do not allow to go below 2.5mm slice thickness
with spectral slice excitation. Are you using standard excitation with FatSat
which may increase SAR and thus increase the TR to compensate with<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Con you provide further information about your protocol to
figure it out<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Regards<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</span></font><font
face=Arial><span style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><st1:place w:st="on"><st2:Sn w:st="on"><font size=2
face="Palatino Linotype"><span style='font-size:10.0pt;font-family:"Palatino Linotype"'>Malek</span></font></st2:Sn><font
size=2 face="Palatino Linotype"><span style='font-size:10.0pt;font-family:
"Palatino Linotype"'> <st2:Sn w:st="on">I.</st2:Sn></span></font></st1:place><font
size=2 face="Palatino Linotype"><span style='font-size:10.0pt;font-family:"Palatino Linotype"'>
Makki, PhD</span></font><font face=Arial><span style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Palatino Linotype"><span
style='font-size:10.0pt;font-family:"Palatino Linotype"'>Diagnostic Imaging
Department</span></font><font face=Arial><span style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><st1:place w:st="on"><st1:PlaceName w:st="on"><font size=2
face="Palatino Linotype"><span style='font-size:10.0pt;font-family:"Palatino Linotype"'>MRI</span></font></st1:PlaceName><font
size=2 face="Palatino Linotype"><span style='font-size:10.0pt;font-family:
"Palatino Linotype"'> </span></font><st1:PlaceType w:st="on"><font size=2
face="Palatino Linotype"><span lang=DE style='font-size:10.0pt;font-family:
"Palatino Linotype"'>Center</span></font></st1:PlaceType></st1:place><font
face=Arial><span lang=DE style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Palatino Linotype"><span lang=DE
style='font-size:10.0pt;font-family:"Palatino Linotype"'>Kinderspital Zurich</span></font><font
face=Arial><span lang=DE style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span lang=DE style='font-size:12.0pt;
font-family:Arial'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Palatino Linotype"><span lang=DE
style='font-size:10.0pt;font-family:"Palatino Linotype"'>Phone. </span></font><font
size=2 face="Palatino Linotype"><span lang=FR style='font-size:10.0pt;
font-family:"Palatino Linotype"'>+41(0)44 266 3130</span></font><font
face=Arial><span lang=FR style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Palatino Linotype"><span lang=FR
style='font-size:10.0pt;font-family:"Palatino Linotype"'>Fax:
+41(0)44 266 7153</span></font><font face=Arial><span lang=FR style='font-family:
Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><a href="mailto:malek.makki@kispi.uzh.ch"><font size=2
face="Palatino Linotype"><span lang=FR style='font-size:10.0pt;font-family:
"Palatino Linotype"'>malek.makki@kispi.uzh.ch</span></font></a></span></font><font
face=Arial><span lang=FR style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</span></font><font
face=Arial><span style='font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;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>susumu mori<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, September 23, 2010
11:28 PM<br>
<b><span style='font-weight:bold'>To:</span></b> DTI Studio, ROI Editor,
DiffeoMap Questions/Support<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Mristudio-users]
What is the difference between a TR 7500 and a TR 17000?</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Usually, one-slice single-shot imaging takes less than 150ms, I
believe. 50 slices thus should take about 50 x 150ms = 7.5 s.<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>This is the repetition time; within this time you are done with one 3D
volume. With 33 directions and 3 b0s, for example, you spend 7.5s x 36 images =
4.5 min.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>If you use repetition time of 17s, your total imaging time will be 17s
x 36 = 10 min.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>So, I would say, 17s is a bit too long and I recommend you to use the
shortest TR, if possible.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>I noticed that some older GE scanners do not allow to use the minimum
TR such as 7.5s probably due to gradient heating. So, if the 17s is the
shortest you can do, then, that is your only option. <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Other than that, 2.2 mm
isotropic could be a bit too small for 1.5T with 33 DWIs. The SNR may be a
noisy side depending on your coil performance. We do 2.5 mm for 1.5T<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Thu, Sep 23, 2010 at 11:51 AM, Lucas Lessa <<a
href="mailto:lucas_lessa@yahoo.com.br">lucas_lessa@yahoo.com.br</a>> wrote:<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>Dear friends,<br>
<br>
I made a new protocol for a GE 1,5T HDX, using 33 directions and 50 slices
with 2.2 mm thickness.<br>
I did this because the vendor programmed a sequence that uses only 12
directions, 20 slices with 5 mm tichness and 1 NEX.<br>
I tried to obtain an isotropic image with more signal.<br>
But to to this I've changed the TR to 17000 (the maximum).<br>
Is there any problem?<br>
And, if is possible, can anyone explain for me the significance of this?<br>
Thank you very much.<br>
<br>
Lucas Lessa.<o:p></o:p></span></font></p>
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<br>
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