1. A method comprising: acquiring, with a detector defining a field of view (FOV), emission imaging data of an object over the FOV; determining, with one or more processing units, a volume of interest (VOI) of the emission imaging data, wherein the VOI defines a volume smaller than an imaged volume of the object, wherein the VOI is determined using a general anatomical model; reconstructing a non-attenuation corrected (NAC) image using the emission imaging data of the FOV; for each of multiple particular organs, performing a projection from a corresponding particular organ model to form a corresponding sinogram mask for the particular organ; performing, with the one or more processing units, a multivariate data analysis using the masks on the VOI to generate at least one waveform for the VOI; for each of plural bed positions, determining organ-specific motion data relevant to motion of each particular organ at each bed position; determining an amount of motion using the organ-specific motion data of each particular organ at each bed position; performing motion mitigation on the VOI based on the amount of motion, without performing motion mitigation on at least a portion of the FOV outside of the VOI, wherein the VOI is determined before performing the motion mitigation; reconstructing an image based on the emission imaging data; and displaying, on a display unit, at least one of information corresponding to the amount of motion or the image reconstructed based on the emission imaging data.