Noise maps of (a) the original cine images, (b) EVM-based aMRI, and (c) phase-based aMRI. The SNR in the original data and EVM-based aMRI are close in value due to the fact that the EVM algorithm amplifies the motion and the noise all together. On the other hand, the SNR of phase-based aMRI is approximately 2.5 times larger than EVM-based aMRI, since EVM-based aMRI amplifies temporal brightness changes and the amplitude of noise is amplified linearly. In contrast, phase-based modifies phases (not amplitudes), and as such does not increase the magnitude of spatial noise.