Elasticity imaging is a new approach to diagnose the state of tissues in vivo. Almost all of elasticity imaging methods have been studied using ultrasound. However, such ultrasound systems can not be applied to the pulmonary tissues because the lung is fulfilled with air and almost power of ultrasound is reflected at the boundary of the lung. This paper proposes a novel tissue elasticity imaging method using multidetector computed tomography (MDCT). The present method estimates the elasticity based on image registration between the inspiratory MDCT images and the expiratory MDCT images of the same subject. Use of the elasticity imaging for the lung will be a powerful tool for diagnosing the lung emphysema, the breast cancer or the other pulmonary diseases that cause the change of elasticity.