XNAT gathers information from the DICOM header fields to retrieve important metadata that can be used to automatically associate the objects with the appropriate project, subject and session. Because these fields are used differently under various conditions, XNAT makes several passes over the headers to gather the required information. If sending data from the scanner console, attempts should be made to satisfy the first or second pass rules. From tools like XNAT’s DICOM Browser and DICOM Batch Editor, the third or fourth pass rules may be easier.
First Pass
In the first pass over the DICOM header content, XNAT looks for all relevant metadata in the Patient Comments field (0010,4000). This is a freeform field that technicians can populate at the console. On Siemens’ Syngo system, the field can be populated from the “Additional Information” box below the patient information (name, date of birth, etc) section. The metadata should be entered as follows:
Project:Project_ID (or Project Alias will work as well) Subject:Subject_ID Session:Session_ID
Eg: Project:BobsProj Subject:subj001 Session:subj001_MR1
AA:TRUE
” in this field as well.Second Pass
Same as above, except using the Study Comments (0032,4000)
field. This field is another freeform field entered at the Syngo console under “Study comments”
Third Pass
In the third pass, XNAT looks for each metadata field in individual DICOM fields, as below:
DICOM Tag | Tag name | XNAT Field |
---|---|---|
(0008,1030) | Study Description | Project ID |
(0010,0010) | Patient Name | Subject Label |
(0010,0020) | Patient ID | Session Label |
Fourth Pass
Same as above, except Accession Number (0008,0050)
is used as Project ID.
Fifth Pass
The fifth pass is only done for Project ID. In the fifth pass, XNAT tries to assign the Project ID using project rules: Step 3 of 8: Configure DICOM project routing
Sixth Pass
There is no sixth pass. If after the five passes described above, XNAT has not satisfactorily matched or identified the metadata, it leaves these fields marked as invalid in the generated XML document. If no Project was identified, the DICOM files will be placed in the “Unidentified” prearchive box. If Project was identified, but Subject and/or Session was not, the DICOM files will be placed in the appropriate project prearchive box. However, the automatic matching tool will not be functional, and additional data entry will be required.