[Mristudio-users] Slice thickness of DTI

[susumu mori]

Hi Santosh,

Practically, the slice thickness, which is the thinner the better, is
determined by SNR.
If you use 2.5 mm, you need about 50-55 slices to cover the entire brain.
2.2 mm needs 55-60 and 2mm needs more than 60. These are all without gaps.

With 5-6 min scans, you can acquire about 40-50 DWIs for 2.5mm/50-slice 3D
data. These numbers decrease as the thickness become thinner and thus more
slices are required and takes longer time.

40-50DWI means about 4 repetitions of 12-orientations.

If you use a 1.5T, you may need more than 60 DWIs with 2.5mm, which takes
about 7-8min. With thinner slices (e.g. 2.2mm), you need longer scans to
achieve good SNR.

With a 3T, 30-40 DWIs would give decent SNR with 2.5mm. With 2-2.2mm slice,
you want more than 50-60 DWIs (5-8min).

These numbers are to achieve a good SNR, which depends on my subjective
judgement. So different people could recommend different numbers, but they
may not be that much different.

As for image distortion, the most important factor is the size of the image
matrix; the smaller the better (I assume that you already use parallel
imaging, which reduces the matrix size into half).

For example, 128x128points / 256x256mm and 96x96/192x192mm both give the
same 2mm resolution, but 96x96 would give better (less) distortion and
better SNR.

On Mon, Nov 26, 2012 at 1:28 AM, Santosh Yadav
<santoshyadav20076 at gmail.com>wrote:

> Hi DTI experts,
>
> Thanks for great supports!
>
> I would like know the recommended slice thickness and gap between the
> slice for DTI data acquisition for 12 directions. Is higher
> Slice thickness( more that 3 mm) have partial volume effect?
>
> Second question: Is eye open during the DTI acquisition have any impact on
> DTI distortion or image quality?
>
> With Best Regards,
>
> Santosh
>
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