Re: [Gdcm2] GDCM cannot get rescale intercept/slope/type from nested objects with undefined length

[Mathieu M. <mat...@gm...>]

Salut Florent :)

On Thu, Aug 17, 2017 at 11:16 AM,  <k3...@fr...> wrote:
> Hi,
>
> I am trying to read a DICOM series (multi-echo series from Philips) but I need to check some DICOM tags first:
> - 0028,1052: rescale intercept
> - 0028,1053: rescale slope
> - 0028,1054: rescale type

So you are dealing with legacy MR Image Storage instance(s) from
Philips Medical System.

> Unfortunately GDCM is not able to find that tags through ITKs API (gdcmIO->GetMetaDataDictionary()), but when I use gdcmdump to search for DICOM tags manually I am able to find the tags but in nested objects with "undefined length":
>
> (2001,1068) ?? (SQ) (Sequence with undefined length)          # u/l,1 ?LinearModalityGLTrafo
>       (fffe,e000) na (Item with undefined length)
>         (0028,1052) ?? (DS) [-12095]                              # 6,1 Rescale Intercept
>         (0028,1053) ?? (DS) [5.90720390720390]                    # 16,1 Rescale Slope
>         (0028,1054) ?? (LO) [normalized]                          # 10,1 Rescale Type
>         (2001,0010) ?? (LO) [Philips Imaging DD 001]              # 22,1 Private Creator
>         (2001,1077) ?? (CS) [LINEARMODALITY]                      # 14,1 GL TrafoType
>         (2001,10c1) ?? (LO) [LinearModalityGLTrafo ]              # 22,1 Nested Object Type Name
>       (fffe,e00d)
> (fffe,e0dd)

Well since the public tag is nested within a private tags, this means
it belong to the extended SOP Class definition. In case you have
access to the DCS of PMS for that particular instance, you should be
able to implement support for it.

> Is there a way to fix that? Did you ever see that kind of nested objects? Is there a configuration on the Philips workstation to avoid that kind of nested objects?
> Thanks.

I am not 100% convince there is anything to 'fix', could you please
send us the output of gdcminfo on that image. This will tell whether
the issue is really at GDCM level or at ITK level. I did implement
support for those Philips 'Combine MR Rescale option', since GDCM
2.6.x

Thanks,
-- 
Mathieu