MRI Alignment Issue in OHIF: Direct DICOM Send vs Manual Upload from Scanner

General
1

Hi everyone,

I am facing a strange issue with Orthanc and OHIF and would appreciate any guidance.

My setup

  • MRI Scanner → Local Orthanc (installed at the client site)

  • Local Orthanc routes studies to our cloud Orthanc using Orthanc Peer (Lua script)

  • OHIF is integrated as an Orthanc plugin on the cloud server.

The issue

For some MRI studies, when the scanner sends the images directly to the local Orthanc via DICOM C-STORE, the study shows an alignment/misalignment issue in OHIF after being routed to the cloud Orthanc.

However, if I export the same study from the MRI scanner console as DICOM files and manually upload those files to Orthanc, the alignment issue disappears and the images display correctly in OHIF.

What I have verified

  • The same cloud Orthanc server is used in both cases.

  • The same OHIF viewer is used in both cases.

  • The issue only occurs with studies received through the scanner’s DICOM send.

  • The manually exported DICOM files from the scanner work correctly.

Routing

The local Orthanc routes studies to the cloud Orthanc using Orthanc Peer through a Lua script.

2

You’ll want to narrow down exactly what step is introducing the issue. To do that, here are the steps I would recommend taking:

  • Install the OHIF viewer on the Local Orthanc instance. Do you see the misalignment in the local instance, or only the Cloud? This will tell you whether the issue is with the Orthanc Peer/Lua Script step.
  • Install a different DICOM listener (e.g. DVTK Storage SCP Emulator or Conquest) and do a DICOM C-STORE to it, then upload the resulting DICOM files to to the Local and/or Cloud Orthanc instances. If you still see the issue, then this would appear to be a problem on the scanner side.
  • With the images that show the misalignment, do you see the problem persist if you open the DICOM files in a different DICOM image viewer? Or is it only in OHIF?
  • DVTK DICOM Compare could help illuminate what is different between the images.
3

Hi, gmancuso thanks for uour advice but I solved the issue, but the behavior is very strange. On my local Orthanc instance, I simply removed the following line from routing.lua:



["Transcode"] = "1.2.840.10008.1.2.4.70"  -- JPEG Lossless

After removing it, the alignment issue was resolved. However, it’s strange because I don’t see this issue on the other machine, even though it uses the same configuration.