Hiya
On 3 Mar 2007, at 07:12, Igor O. Korolev wrote:
>
> Specifically:
>
> 1) Which scanner was the diffusion data collected on? Was it a GE
> scanner?
>
Siemens Allegro
> 2) What scanner parameters were used to collect the diffusion data?
>
> a. It looks like 65 volumes comprise the DTI data; does this mean
> that that data contains 64
> diffusion-weighted volumes (representing 64 gradient directions)
> and 1 non-weighted volume?
There are 60 diffusion-weighted volumes and 5 b=0 volumes
> b. Was the tutorial data constructed from a single DTI scan or were
> multiple scans averaged to
> remove noise? If so, how many scans were averaged?
3 scans were averaged
> c. The diffusion data has a voxel size of 2 x 2 x 2 mm; is this the
> voxel size of original / raw data
> as it came out of the scanner ? if not, what was the original voxel
> size and how (using what
> program and resampling method) was the data re-sampled / interpolated?
>
Native voxel size - ALWAYS DO THIS!
> d. What inter-slice spacing was used for the DTI dataset?
Can't remember, but I suspect none.
> e. What was the magnetic field strength of scanner used?
3T
> f. What DTI sequence was used to collect data? (standard echo-
> planar imaging, line-scan diffusion
> imaging, FLAIR-DTI, etc.)
>
EPI
> 3) How was the raw / original DTI data prepared / pre-processed to
> obtain the supplied tutorial
> data?
>
> a. Was the raw data resampled / re-sliced ? If so, how?
NO
> b. Was the raw data averaged across multiple scans to remove noise?
We ran eddy current correction on the complete 195 volume dataset, to
align all volumes, and then split out the three datasets and averaged
them.
> c. Were any specific steps taken (in addition to the Eddy Current
> Correction in FDT) to remove /
> correct for (1) motion artifacts and (2) image distortion artifacts
> in the raw DTI data? If so, what
> software was used to do this?
None - Although soon, we will be recommending some clever siftware
that Jesper Andersson is writing to do lots of fancy preprocessing
(but it requires slightly different data).
> d. Were any other steps / parameters implemented to remove noise /
> artifacts in the raw DTI data,
> either during scanning or during pre-processing of the data?
>
No.
Cheers
T
> Thank you very much for your time and help. I look forward to
> hearing from you soon.
>
> Sincerely,
>
> Igor Korolev
> PhD student
> Neuroscience Program
> Michigan State University.
|