<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi,<div><br></div><div>I am inspecting my DTI data and find that for some gradient directions (almost 10 out of 30) this hole-like artifact near central sulcus (very superior) appears. I am attaching an example from a DTI studio screenshot and the b0 image as a reference.</div><div>The images were acquired with a 3 Siemens Magnetom, 50 axial slices, slice thickness 3mm, TR 6400ms, TE 88 ms, 4 averages, FOV 128 x 128; Grappa, Accel. Fact 2, 30 gradient directions, Phase Enc Direction A->P, b value 800, the patient was anesthetized.</div><div><br></div><div>I also think that there is quite a bit of b0 distortion despite parallel imaging. </div><div><br></div><div>My questions are: 1) what causes these artifacts (I have seen them in other scans/patients at different locations - could it be the effect of a large blood vessel or other kinds of motion)?</div><div>2) How can I avoid such artifacts?</div><div>3) Is there any way of 'saving' the data - other than throwing those images out</div><div>4) If I have to remove these images - how will that affect the tensor calculation/FA maps/fibertracking?</div><div><br></div><div>Thank you very much.</div><div>Katja</div><div><img height="96" width="968" apple-width="yes" apple-height="yes" id="56fe32f3-63cd-40a9-b4b5-97403d0fd273" src="cid:C29EC250-AD2A-453F-A961-A37A3D43E4FD"></div><div><img height="96" width="968" apple-width="yes" apple-height="yes" id="adb6b484-fa14-436d-9b4e-46c806747e08" src="cid:27453533-FCF0-4220-B289-7B30B72E3386"> <br><div><div>
<div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-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; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-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; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><font class="Apple-style-span" face="Arial"><br></font></div></div></span></div></span></div></div></div></div></div></body></html>