mriconvert: basic usage, dti reordering and fsl nifit question

Tue Aug 23 13:34:29 PDT 2016

2. Volume reordering – volumes in MRIConvert are sorted according to a “key”
that determines which file belongs to which volume. This does not always
correspond to the temporal order of acquisition (we don’t typically use
acquisition time, because it isn’t always a meaningful part of the “key” –
think about a double echo sequence for example). This means volumes are not
always in the same order they were acquired, which I know can be a little
annoying, but the bvals/bvecs that are output will be in the same order as
the output volumes, which is the most important thing. 

3. I *think* all FSL tools now fully support 16 bit unsigned files, which
means “nifti” output type should work fine. Most FSL operations convert the
files to floating point right off the bat anyway. Reminder, the difference
between “nifti” and “fsl/nifti” are a) “fsl/nifti” will convert files to
either 16 bit signed or floating point (for images using more than 12 bits),
while “nifti” leaves the image data in its original format, and b)
“fsl/nifti” applies a top/bottom slice-wise flip to the data, in an attempt
to get the images into what fsl considers “standard orientation”. Both are
valid nifti files, and I usually run “fslreorient2std” first anyway which
seems to prevent a lot of orientation problems.

Jolinda

From: mriconvert-bounces at lists.uoregon.edu
[mailto:mriconvert-bounces at lists.uoregon.edu] On Behalf Of Scheel, Michael
Sent: Tuesday, August 23, 2016 1:14 PM
To: mriconvert at lists.uoregon.edu
Subject: Re: mriconvert: basic usage, dti reordering and fsl nifit question

Dear Christina, 

thanks so much for you reply. That works! 

Do you or someone else has an idea about:

2) DTI conversion - volumes reordered

3) FSL Nifti - 16bit unsigned issue

Thanks, Michael

On 23.08.2016, at 10:30, Chr. Rossmanith <cr at NEURO.MA.UNI-HEIDELBERG.DE
<mailto:cr at NEURO.MA.UNI-HEIDELBERG.DE> > wrote:

Hi Michael,

maybe an example for file name creation is helpful: 

mcverter --fnformat="My_%PN_%SN" -f fsl -n ...

creates files with names like My_Foo_001_0001.nii, My_Foo_001_0002.nii, ...
, My_Foo_002_0001.nii

i.e. format elements are a combination of some fixed strings ("My") and
variables taken from the image header prepended with '%' (%PN or %SN).

Christina Rossmanith
--
Dept. of Neurology
University Medicine Mannheim
University of Heidelberg
Germany

On 23.08.2016 09:51, Scheel, Michael wrote:

Dear all,

i am a new user of mriconvert (dcm2nii previously) and i am very happy about
the functionality (e.g. about the output of the info.txt file)

and also all the background information that I found in the programm itself
and on this mailing list  (e.g. to File formats especially the details to
fsl nifti)

I have some very basic questions that I hope the mriconvert experts can help
me with

1) Usage of --fnformat=<str>

I am unsure on how to provide format strings for custom naming of output
files

Usage: mcverter [-h] -o <str> -f <str> [-v] [-q] [-V] [-j] [-x] [-d] [-a]
[-n] [-b] [-r] [-u] [-s <str>] [-m <str>] [-F <str>] Input directory or
file(s)...
  -h, --help            Show this help message

..

 -F, --fnformat=<str>

Use this format for name of output file: 
format = {format element} ;
some text = {filesystem-legal characters} ;
format element = {some text} , {"%" "PN" | "PI" | "SD" | "ST" | "SI" | "TD"
| "SN" | "SQ" | "PR" | "RD"} , {some text} ;
or 
format = {"+" | "-" , "PatientName" | "PatientId" | "SeriesDate" |
"SeriesTime" | "StudyId" | "StudyDescription" | "SeriesNumber" |
"SequenceName" | "ProtocolName" | "SeriesDescription"

I would like to have a custom output filename but I am unsure on how I
should provide the format elements.

Could you give me some examples for actual commands

I tried the following but this will rename the file into
{"PatientName”}.hdr/img

mcverter -o conversion_fsl_3 -v --fnformat={"PatientName"} dicom

2) DTI conversion - volumes reordered

I have a DTI dataset with 1b0 volume and 12 directions with 8 repetitions.

It was originally acquired 

b0_rep1 dir1_rep1 dir2_rep1 dir3_rep1 dir4_rep1 dir5_rep1 dir6_rep1
dir7_rep1 dir8_rep1 dir9_rep1 dir10_rep1 dir11_rep1 dir12_rep1 b0_rep2
dir1_rep2  
. dir12_rep8

after conversion the volumes and also the respective bvals and bvecs entries
in my case get resorted

b0_rep1 b0_rep2 b0_rep3 b0_rep4 b0_rep5 b0_rep6 b0_rep7 b0_rep8 dir1_rep1
dir1_rep2 dir1_rep3 dir1_rep4 dir1_rep5 dir1_rep6 dir1_rep7 dir1_rep8
dir2_rep1 dir2_rep2 
.

Is this intended and if so why?

3) FSL Nifti - 16bit unsigned

I have seen that there has been a discussion on FSL supporting 16bit
unsigned. As this led to any results?

Best wishes, Michael

Michael Scheel, MD
Neurodiagnostics Laboratory
and Clinical Neuroimmunology Group
NeuroCure Clinical Research Center
Charité - Universitätsmedizin Berlin
Charitéplatz 1
10117 Berlin, Germany

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