A device (10) for measuring respiration of a patient includes a positron emission tomography (PET) or single photon emission computed tomography (SPECT) imaging device (12). At least one electronic processor (16) is programmed to: extract a first respiration data signal (32) from emission imaging data of a patient acquired by the PET or SPECT imaging device； extract a second respiration data signal (36) from a photoplethysmograph (PPG) signal of the patient； and combine the first and second extracted respiration data signals to generate a respiration signal (40) indicative of respiration of the patient.
