A method for determining a signal representation of a subject in MRI is provided. The method may include acquiring a plurality of signals of the subject. The plurality of signals may be generated using an MRI device, and each of the plurality of signals may correspond to a set of values in a plurality of signal dimensions of signal acquisition using the MRI device. The method may include determining, among the plurality of signal dimensions, a primary signal dimension and at least one secondary signal dimension, the primary signal dimension being associated with the signal representation. The method may also include determining the signal representation of the subject based on the primary signal dimension, the at least one secondary signal dimension, and the plurality of signals.
