M4Raw: A multi-contrast, multi-repetition, multi-channel MRI k-space dataset for low-field MRI research [V1.6]

V1.6 release notes:

• The test subset is released, which contains T1w (6 repetitions/subject), T2w (6 repetitions/subject), and FLAIR (4 repetitions/subject) data from 25 new subjects. These data have passed motion inspection, but one should note that due to the doubled repetition numbers, the average inter-contrast motions are around twice larger than those in the training and validation subsets. To facilitate users, we release the ground truth images as well, but please do not use them during hyperparameter tuning.

V1.5 release notes:

• T1w Gradient echo (GRE) data for all 183 subjects are released. Note that the phase encoding direction for GRE data is in the AP direction, different from other contrasts. These GRE data were not checked for motions.
• A few incorrect records of patient_id were corrected in the H5 files.
• Scans 2022062708 and  2022062709 were removed due to duplication. Two new scans were added to replace them.

V1.1 release notes:

• Please refer to https://www.nature.com/articles/s41597-023-02181-4 for details.