T2w_vNav - Black streak artefact?

Hi, We have just begun collecting data on 3T Siemens PRISMA using ABCD sequences including the T2w_vNav which seems to be having a black streak artefact. This artefact seemingly disappears when the acceleration factor 3D is changed from 3 to 1 and the acceleration factor PE is changed from 1 to 3.

Has anyone had this experience ?

What are the repercussions of swapping the types of acceleration factors ?

Thanks
NB

Hi @Sotsub ,

Could you share a screenshot showing the artefact?