Pseudo-continuous-arterial-spin-labeling (PCASL) has been successfully applied in the lung providing high quality perfusion images. The pulmonary blood flow and the respiratory system interact closely: the intrathoracic pressure has impact on the venous return. Therefore, in this work, we evaluate the effects of intrathoracic pressure on lung perfusion by using PCASL imaging in end-expiratory and end-inspiratory breath-hold. PCASL imaging is able to detect changes of parenchymal lung perfusion caused by alterations of the intrathoracic pressure. Perfusion signal measured under end-inspiratory condition were noticeably reduced as compared to end-expiratory breath-hold. This correlated significantly with measured blood flow volume through the pulmonary trunk.