Systems and methods for estimating complex transmit field B1+ a transmit coil of a magnetic resonance imaging (MRI) system in both k-space and image domains are described herein. Estimating complex RF field B1+ in the k-space domain includes acquiring complex data in a k-space domain, estimating a complex B1+ map in the k-space domain of a transmit coil and storing the complex B1+ map. The complex B1+ map can be estimated based on the complex images. Estimating complex transmit field B1+ in the image domain includes acquiring at least two complex images in a k-space domain, transforming the complex images into an image domain, estimating a complex B1+ map in the image domain of a transmit coil, and storing the complex B1+ map.
