Unsupported OCT SOP Class?

[Adam Harding]

I need to store Cirrus OCT. I believe the DICOM from the scanner has
SOP Class UID 1.2.840.10008.5.1.4.1.1.12.77, which is incorrect and
needs instead to be 1.2.840.10008.5.1.4.1.1.77.1.5.4. I have to double-
check with the researcher on where the incorrect SOP class is coming
from, and on whether or not it's possible to correct at the same time
we decrypt the DICOM before forwarding to DicomServer/XNAT.

The correct SOP class is recognized ("Ophthalmic Tomography Image")
but unsupported. It's documented in supplement 110 here:
http://www.dclunie.com/dicom-status/status.html#SupplementsByNumber
ftp://medical.nema.org/medical/dicom/final/sup110_ft4.pdf

We don't think the Cirrus scanner actually uses any of the special
features in the supplement. Does anyone have advice on what to do in
such a situation? I haven't created any custom types yet, and I
imagine there needs to be a session handler for it too. I'm testing on
XNAT 1.4 release / DicomServer r702, and have some 1.4rc4 test
instances that may get upgraded rather than clean-installed.

Thanks,
Adam

[Kevin Archie]

Adam,

Just for clarification: is the modality Ophthalmic Tomography (OPT), with SOP class 1.2.840.10008.5.1.4.1.1.77.1.5.4 ? We'll need to add that modality and SOP class as a supported type in DicomServer. I should be able to make that change and have the updated DicomServer available for download later today.

You may ask: why haven't we implemented this already? Because until now, we didn't know anyone using OPT. I'll make the DicomServer change, but the XNAT representation of these data will be very minimal -- not much beyond date, time, UIDs, and scanner name. If possible, we'd like to talk briefly with someone using this modality about which DICOM fields are important to represent in XNAT, by which I mostly mean which fields would they like to be able to use in searches. This conversation will help us to improve the schema and provide better support for your users.

Thanks!

  - Kevin

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[Adam Harding]

Kevin,

Thanks for your response. I'll send a private email to you and the
person working with this modality.

> Just for clarification: is the modality Ophthalmic Tomography (OPT), with SOP class 1.2.840.10008.5.1.4.1.1.77.1.5.4 ?

Yes, that's the SOP class in question.

I'd be happy to download it perhaps tomorrow or next week when it's
ready and give it a shot. FYI: This is for ICTS at the University of
Iowa, and we anticipate having to deal with a very broad range of
modalities, so if you have any preferred way to handle this type of
request, just let me know.

Thanks,
Adam

[Kevin Archie]

I'm attaching a jar file to this message; place it in your DicomServer lib/ directory (replacing the jar of the same name) and restart your DicomServer to add support for OPT sessions.

If you will need a few more modalities, it would be helpful (though by no means necessary) if you could send me a complete list so I can get them all in one pass. With each, it would also be helpful if you could put us in touch with a user familiar enough with the modality to answer questions about the importance of various fields.

Thanks,
- Kevin

[Adam Harding]

Kevin,

Thanks for the modifications; I should get to testing yet today. I'll
try to bundle such requests if possible, but they'll likely be a bit
sporadic as researchers and departments become engaged.

I'm also emailing you and the person working with this modality.

Adam

>  dcm4xnat-1.4.jar
> 86KViewDownload

[Adam Harding]

Andreas reports the researchers are interested in these:
-----------------------------------------------
We discussed that the parameters currently shown in the web interface
(including MR-specific ones like imaging sequence and time weighting)
are not adequate for other modalities like OCT or ultrasound (which we
tried to "sell" the OCT images to the XNAT system during our initial
testing). I have received by now some attributes the researchers would
like to see in that window or search for (i.e., likely would need to
be
indexed in the database). I'll correlate those with the DICOM
elements...

...

These are items they would likely search for -

1. Some way to identify the machine, e.g., by vendor
(0008,0070) LO [Carl Zeiss Meditec, Inc.]

2. Laterality (left or right eye = OD or OS)
(0020,0060) CS [OS]

3. Performed scan type
(0040,0260) SQ [PerformedProtocolCodeSequence]
(0008,0104) LO [Macular Cube ...]

Nice being able to search for, should be displayed as a minimum -

4. Image format and resolution
(0028,0008) IS [NumberOfFrames]
(0028,0010) US [Rows]
(0028,0011) US [Columns]
(0028,0030) DS [PixelSpacingX,PixelSpacingY]
(0018,0088) DS [PixelSpacingZ]

5. Any comments added by the personnel (free text)
(0008,103e) LO [SeriesDescription]
(0010,4000) LT [PatientComments]

Unless those are used for Xnat sorting purposes.

...

from Supplement 110:

(0022,0055) Illumination Wave Length
(0022,0056) Illumination Power

Again, the modailities used don't support this group, thus it may be
currently mood to add those, but just in case it is difficult to add
items to the database at a later time.
-----------------------------------------------

How extensive a project is this? I know there's fairly keen interest
among the ophthalmology community here about being able to start using
XNAT, so let us know if there's anything Andreas or I can do to
facilitate the implementation. Development contributions aren't out of
the question, but this seems like a set of changes spanning most of
the technologies XNAT uses and we haven't done anything more than very
simple modifications yet.

Kevin, you mentioned in your email from 4/26/10 that another user was
working on this type of capability; how substantial is the overlap
here?

Thanks,
Adam

> > >>> I need to store CirrusOCT. I believe the DICOM from the scanner has

[Archie, Kevin]

Hi, Adam,

Most of what's described below, being purely metadata, will be straightforward to implement: there will be a small change to the schema and a similarly small change to the metadata translation code. The performed scan type is going to be tricky; let me think about how we might sneak a value out of a sequence (we haven't had to do this before now). Storing the files should be no big challenge. The hard part in storing multiframe data is going to be figuring out how to represent access to individual frames, and then making various pieces (snapshot generation, image viewer) work with these multiframe files.

I'll try to have the easy parts ready for you next week.

- Kevin