Animal model make the precise detection of ventilatory phase difficult, and the relatively high ventilation rates seen in small animals. The aim of this study was to develop cardiac and respiratory motion correction system with list-mode acquisition for the small animal microPET scanner. We utilized a commercially available slim force sensor to detect respiratory motion and trigger generating device built in-house during microPET scanning. The CT images obtained with the clinical CT scanner can be used to improve the anatomical localization of uptake in the microPET images. A method for co-registering CT and microPET images was developed to improve the anatomical localization of PET uptake. This technique improves the quantitative specific activity of the tracer, which is distorted because of the respiratory motion.