[Bug] Multiframe DICOM negative Spacing Between Slices not handled

[salimkanoun]

Describe the Bug

In multiframe DICOM, some of theme has a negative 0018,0088 Spacing Between Slices exemple 0018,0088 Spacing Between Slices: -4.41806

According to the dicom standard in the case of NM images "The normal is determined by the cross product of the direction cosines of the first row and first column of the first frame, such that a positive spacing indicates slices are stacked behind the first slice and a negative spacing indicates slices are stacked in front of the first slice"

In the current version, Cornerstone only take in consideration 0018,0050 Slice Thickness resulting that DICOM with negative spacing between slices are upside down.

Here are two samples with this issue: Bone scitigraphy https://nc-6563074006263353659.nextcloud-ionos.com/index.php/s/yYjXZxapM77WMYF Datscan https://nc-6563074006263353659.nextcloud-ionos.com/index.php/s/Nt8qkxEw2NMNM6A

Steps to Reproduce

Open OHIF with config strictZSpacingForVolumeViewport: false Open the Datscan image with basic mode, go to MPR The brain is upside down (see vertex being down)

Open the bone scintigraphie in basic and go to MPR, see the bladder uptake in upper part of the viewport

Modify the TMTV mode to try to fuse the NM (here labeled OT has reconstruction in NM is not native) with CT

• An error occur
• We can see the mismatch of the two series

The current behavior

upside down image

The expected behavior

image stack should be done in reverse order if Spacing Between Slices is negative

OS

Linux

Node version

20+

Browser

Chrome 100+