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I have a few doubts in technological aspects of MRI k-space data handling (storage and transfer through network(from MR machine to processing system).
Have any standard format or mechanism for it?
Have any standard tags(or standard MR SOP class)in DICOM for embedding and transferring MRI K-Space data?
What is the mechanism used by popular MR suppliers used for data transfer of K-space data?
Have any commonly used standard or private data format for MRI K-space or raw data handling

There are no DICOM tags, fields, or DICOM-approved methods for transferring/saving raw data. Likewise, there is no uniform method among vendors for formatting this data.

All MR manufacturers provide methods for downloading and saving raw data but they are vendor-specific, and you will need to check with them for specific details.

There is an ISMRM driven initiative to standardize a method of describing raw data to allow researcher collaboration. See http://ismrmrd.github.io/. There are a few vendor specific open-source, reverse engineered convertors. See https://github.com/ismrmrd.