[Mristudio-users] Calculating SNR of DTI data

[Seongjin]

My opinions to (3) and (4)

(3) In parallel imaging, SNR decreases as acceleration factors increases (R
in Philips system).
But increased acceleration factors improves geometric distortions (i.e.
better shape).
You need to find trade off point with your data. In Philips 3T system, I
observed significant noise in the images using acceleration factor larger
than 3 (R > 3).

(4) When you do DTI using parallel imaging, normal SNR methods will not
work. You need to have signal image and noise only image. Get the mean
signal and noise standard deviation from an ROI then calculate the SNR. You
can get noise-only image in RF-off mode.

-Seongjin


On Mon, Jun 28, 2010 at 7:37 PM, Juranek, Jenifer <
Jenifer.Juranek at uth.tmc.edu> wrote:

>  While the issue of SNR effects on DTI metrics is discussed in the
> published literature, I have found relatively little information regarding
> calculating SNR as a screening procedure for image quality. A few authors
> have reported the SNR range (or cut-off) of their datasets - but not many.
> I'm curious about the following questions...any responses/opinions would be
> very helpful.
>
>
>
> 1) Is calculation of SNR an effective screening tool for image quality in
> DTI research?
>
> 2) Is calculation of SNR helpful for determining the feasibility of pooling
> 3T DTI data from different scanner platforms (e.g. Siemens and Philips)
>
> 3) To what extent do parallel imaging and acceleration factors affect
> measures of SNR?
>
> 4) If calculation of SNR is a "good thing to do and report", then what is
> the best approach?
>
>
>
> In particular, datatype for analysis (e.g. b=0, trace, DW) and location
> "inside the brain" seem to be important things to consider. In terms of
> datatype, I have seen folks use single non-averaged b=0 for each subject,
> and a mathematical relation between sequential b=0 images, and some have
> averaged their b=0 data on the scanner.
>
>
>
> Many thanks for any feedback,
>
> Jenifer
>
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