1. A method for generating a Positron Emission Tomography (PET) attenuation correction map, said method comprising: obtaining a Magnetic Resonance (MR) image dataset of a subject of interest; obtaining a PET emission dataset of the subject of interest; segmenting the MR image dataset to identify at least one object of interest; determining a volume of the object of interest; and generating a PET attenuation correction map using the determined volume.