[Mristudio-users] artifact

[Fred Tam]

Hello, Katja. Your artifact looks somewhat like the one examined (and
corrected/avoided) here:

	Gallichan D, Scholz J, Bartsch A, Behrens TE, Robson MD, Miller KL
(2010): Addressing a Systematic Vibration Artifact in diffusion-Weighted
MRI. Hum Brain Mapp 31:193-202.

Fred


On Fri, 2010-10-22 at 10:15 +0300, Katja Doerschner wrote:
> Hi,
> 
> 
> 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.
> 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.
> 
> 
> I also think that there is quite a bit of b0 distortion despite
> parallel imaging. 
> 
> 
> 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)?
> 2) How can I avoid such artifacts?
> 3) Is there any way of 'saving' the data - other than throwing those
> images out
> 4) If I have to remove these images - how will that affect the tensor
> calculation/FA maps/fibertracking?
> 
> 
> Thank you very much.
> Katja
> 
>  
> 
>