There are strict rules for UID formatting and usage. If these are not followed, then some modality equipment may refuse to accept MWL results containing invalid UIDs. Some of the systems are known to filter out requests for faulty UIDs.

The most common reasons for StudyUID not being accepted by modalities in Modality Worklist response are:

• Invalid StudyUID formatting including:

  • Leading “0"s in a component. - Each component must be capable of being represented unambiguously as either a string or an integer, so this UID is OK

    - 1.2.826.0.1.3680043
    The 0 is on its own and unambiguous
    
    - But this is not
    
    - 1.2.827.0.1.03680043
    The leading zero in 03680043 is superfluous and illegal
    
    \
    \
    

• StudyUID in the wrong attribute (it must be a top level attribute, not within a sequence)

\

Further cautions and information about StudyUID in MWL results:

• Returned StudyUIDs must be unique
• Less obvious, and often done wrongly, is the requirement that the same UID should be returned for each request for the same information, so creating UIDs “on the fly” when responding to MWL requests is not acceptable

For more details on UIDs, please see article on UID Rules