I'm working with MB data from a Siemens Prisma Fit...and it looks like the following dicom tag might provide info wrt the MB factor used?
Is there a dicom tag that reports which SMS sequence/ build version was used (e.g. CMRR or MGH)?

(0020,4000) Image Comments VR: LT Length: 28 Value: Unaliased MB3/PE3/LB SENSE1

Many Thanks,
JJ

dcm2niix will report the multi-band in the 'description'  field of the NIfTI header, e.g. for multiband x2 series 25 from https://github.com/neurolabusc/dcm_qa:

$ fslhd fMRI_MB_asc_25.nii
 descrip TE=34;Time=140149.418;phase=1;mb=2

If you have dcm2niix create a BIDS JSON text file, you can look at your BIDS file:
"MultibandAccelerationFactor": 2,
"SoftwareVersions": "syngo_MR_B17",
 "PulseSequenceDetails": "%CustomerSeq%_cmrr_mbep2d_bold",

Note that the general purpose DICOM tag [url=http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0020,4000)]0020,4000[/url] stores user defined comments. While these sometimes store multi-band comments, this is not always the case. Therefore, for Siemens images, dcm2niix reads the proprietary CSA header.

Thanks so much for the great tips where to look after I have converted the dicoms (love your dcm2niix and MRIcroGL).
Cheers,
JJ