How to add annotations to a resource using the REST API?

[Farhood_Etaati]

Hello.

I am trying to set up a labeling pipeline for medical data, and we are using ORTHANC as our DICOM server as of now. The REST API of ORTHANC has methods for creating and deleting resources, but I could not find anyway to update a resource there.

The annotations for each resource can be a segmentation mask, or a classification tag (label), or both.

1. Is it possible to do such a thing? Or should I delete and recreate resources everytime I want to update?

2. How should annotations be stored?

Thanks!

[jodogne]

Hello,

DICOM resources are immutable in order to ensure medical traceability, so you cannot “update” them without recreating another DICOM instance with a different SOP Instance UID.

You essentially have 2 possibilities:

• Either store your annotations as separate DICOM instances (cf. DICOM-SR, DICOM GSPS…), or

• Store your annotations as attachments or metadata to an existing DICOM study/series/instance: https://book.orthanc-server.com/faq/features.html#metadata-attachments

HTH,
Sébastien-