A method for magnetic resonance imaging (MRI), comprising: receiving , by at least one processor , a first magnetic resonance (MR) gradient echo dataset corresponding to a first flip angle and a first spoiled gradient echo MR sequence and a second MR gradient echo dataset corresponding to a second flip angle and a second spoiled gradient echo MR sequence, the first MR gradient echo dataset and the second MR gradient echo dataset acquired by imaging an anatomical region using at least one echo time, the first flip angle different from the second flip angle; generating , by at least one processor , an apparent longitudinal relaxation time (T 1app ) map, representing a spatial distribution of T 1app within the anatomical region using the first MR gradient echo dataset, the second MR gradient echo dataset and a constant value for a transmit radio frequency (RF) field within the anatomical region; estimating , by the at least one processor , a first transmit RF field map by scaling the T 1app map by a first constant value of longitudinal relaxation time (T 1 ), the first constant value of T 1 associated with a first tissue type within the anatomical region; estimating , by the at least one processor , a second transmit RF field map by scaling the T 1app map by a second constant value of T 1 , the second constant value of T 1 associated with a second tissue type within the anatomical region; and generating , by the at least one processor , a third transmit RF field map using a first region of the estimated first transmit RF field map corresponding to the first tissue type in the anatomical region and a second region of the estimated second transmit RF field map corresponding to the second tissue type in the anatomical region, the third transmit RF field map representing a spatial distribution of the transmit RF field within the anatomical region. receiving , by at least one processor , a first magnetic resonance (MR) gradient echo dataset corresponding to a first flip angle and a first spoiled gradient echo MR sequence and a second MR gradient echo dataset corresponding to a second flip angle and a second spoiled gradient echo MR sequence, the first MR gradient echo dataset and the second MR gradient echo dataset acquired by imaging an anatomical region using at least one echo time, the first flip angle different from the second flip angle; generating , by at least one processor , an apparent longitudinal relaxation time (T 1app ) map, representing a spatial distribution of T 1app within the anatomical region using the first MR gradient echo dataset, the second MR gradient echo dataset and a constant value for a transmit radio frequency (RF) field within the anatomical region; estimating , by the at least one processor , a first transmit RF field map by scaling the T 1app map by a first constant value of longitudinal relaxation time (T 1 ), the first constant value of T 1 associated with a first tissue type within the anatomical region; estimating , by the at least one processor , a second transmit RF field map by scaling the T 1app map by a second constant value of T 1 , the second constant value of T 1 associated with a second tissue type within the anatomical region; and generating , by the at least one processor , a third transmit RF field map using a first region of the estimated first transmit RF field map corresponding to the first tissue type in the anatomical region and a second region of the estimated second transmit RF field map corresponding to the second tissue type in the anatomical region, the third transmit RF field map representing a spatial distribution of the transmit RF field within the anatomical region. <EOS>