[IGSTK-Developers] Image file format

[Mathieu Malaterre]

David Gobbi wrote:
> Hi Mathieu,
> 
> There actually is a standard for multi-dimensional DICOM, I had a 
> contract where I had to visualize 4D cardiac data a couple years ago.  
> For Nuclear Medicine (NM) images, the 4D image is stored in a single 
> file, and for US to though I've never seen a 4D US.
> 
> For nuclear medicine, the multi-dimensional module is described in 
> Chapter 3, C.8.4.8 "NM Multi-frame Module".  

Oooops. I was looking for something like that for CT/MR and never 
realized it was allowed for other modalities. Nice to know, thanks.

> Ultrasound and X-ray DICOMs 
> also use multi-frame images to support the time dimension, as described 
> in Chapter 3, C.7.6.5 "Cine Module".  If an ECG was used during the 
> acquisition, then the ECG waveform is also stored in the DICOM image.

ok

> For CT and MR, there is a "Temporal Position Identifier" tag (0020,0100) 
> is supposed to give the time index for each image in the series, but I 
> know that not all manufacturers use this tag.  I've never found a good, 
> standardized way of dealing with 4D CT and MR.  Instead I just assume 
> that if any two slices are at the same position, they must be at 
> different times.  Do you use a similar method in ITK to sort a 4D series 
> into a four-dimensional image?

Last time I tried, it required more user input. Eventhough you are able 
to sort all the 3d volume: without visualization you could not sort them 
among each other. I know at least one case where the header would not 
contain any information telling you which one was acquired before the 
other. Just because of that I don't believe the magic in GDCM is good 
enough to deal with all cases.

Mathieu