The present technology relates generally to respiratory motion correction and associated systems and methods. In particular, several embodiments are directed to respiratory motion correction using internal-external motion correlation. For example, one embodiment of a method of correcting motion blurring in PET/CT imaging includes obtaining PET/CT imaging data of a target tissue in a patient and determining a centroid of the target tissue. The method can further include obtaining an external motion signal of the patient and determining a mean displacement of the external motion signal. The centroid of the target tissue can be correlated with the mean displacement and, based on the correlation, a PET/CT image corrected for motion of the target tissue can be reconstructed.
