Abstract: Variable flip angle techniques with constraints for reconstructing MR images include a processor generating a T1app map representing a spatial distribution of T1app within an anatomical region using a first MR dataset corresponding to a first flip angle (FA) and a second MR dataset corresponding to a second FA. The processor can estimate a first and second transmit RF field maps by scaling the T1app map by a first constant value of T1 associated with a first tissue type and a second constant value of T1 associated with a second tissue type, respectively. The processor can generate a third transmit RF field map using the first and second transmit RF field maps, and use the third transmit RF field map to construct MR images of the anatomical region. Weighted subtraction images can be created with improved contrast-to-noise ratio compared to images of the first and second MR datasets.