`falconz` Incorrectly Performing Motion Correction for Nearly Empty Moving Images

[LalithShiyam]

Describe the bug

When using falconz for 4D total-body PET motion correction, the program is incorrectly including nearly empty moving images for motion correction, despite the fact that NCC should be below the acceptable threshold. This deviates from the expected behavior, where the program should discard such images based on the NCC criteria.

To Reproduce

Steps to reproduce the behavior:

falconz -d <path_to_the_dir> -r deformable

Expected behavior

The program should skip the motion correction for nearly empty moving images if the NCC between the fixed and moving image is less than 0.6 * mean(NCC voxelwise).

Actual behavior

The program is performing motion correction even when the moving image is nearly empty and its NCC with the fixed image does not meet the criteria.

Possible Solution

I am currently investigating this issue. At this moment, a fix or workaround has not been identified. Any contributions or insights into this issue are highly appreciated.