Hi Katja,<div><br></div><div>It is difficult to say anything without looking at the images. Usually if you find a localized signal drop, that is due to motion. However, they appear typically around the 4th ventricle and rarely around the central sulcus. Also, 10 out of 30 seem too many. Siemens had some issues in the past with signal drop usually in the occipital lobe.</div>
<div><br></div><div>I thought you can attach a small file with some screenshots?<br><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div style="word-wrap:break-word">
<div><div><br></div><div>My questions are: 1) what causes these artifacts (I have seen them in other scans/patients at different locations, e.g. posterior tip of the occipital lobe) - could it be the effect of a large blood vessel or other kinds of motion)?</div>
</div></div></blockquote><div>> I have to see the images. If you want, you can upload your data to our ftp site.</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word"><div><div>2) How can I avoid such artifacts?</div></div></div></blockquote><div> > see above.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word"><div><div>3) Is there any way of 'saving' the data - other than throwing those images out</div></div></div></blockquote><div>> 10 out of 30 seem too many to save. Usually the artifacts are linked to a particular gradient axis; for example, whenever X axis is applied, the artifact appears. If so, you lose all X gradient orientations and the data can't be saved.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div style="word-wrap:break-word"><div><div>4) If I have to remove these images - how will that affect the tensor calculation/FA maps/fibertracking?</div>
</div></div></blockquote><div>> see above </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div style="word-wrap:break-word"><div><div><br></div><div>Thank you very much.</div>
<div>Katja</div><font color="#888888"><div>
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><div style="word-wrap:break-word">
<div><font face="Arial"><br></font></div></div></span></div></span></div></span></div></span></span></div></font></div></div><br>_______________________________________________<br>
mristudio-users mailing list<br>
<a href="mailto:mristudio-users@mristudio.org">mristudio-users@mristudio.org</a><br>
<a href="http://lists.mristudio.org/mailman/listinfo/" target="_blank">http://lists.mristudio.org/mailman/listinfo/</a><br>
Unsubscribe, send a blank email to: <a href="mailto:mristudio-users-unsubscribe@mristudio.org">mristudio-users-unsubscribe@mristudio.org</a><br>
<br></blockquote></div><br></div>