Pulmonary circulation, extravascular water, and solute flux as determined by positron emission tomography

Pulmonary edema is the result of an increased transpulmonary flux of water and solute and a concomitant insufficiency of lung lymphatic drainage. Although this pathogenetic concept seems well-established, the microcirculatory details of pulmonary edema formation and its ultimate resolution are still poorly understood. For example, how do regional changes in pulmonary blood flow affect the resolution of pulmonary edema, and in turn, how do they affect pulmonary gas exchange? When does vascular permeability return to normal after acute lung injury? Is the severity of the permeability defect related to prognosis, and can therapy hasten either the resolution of altered permeability or the accumulation of extravascular lung water? These and similar questions are approachable with positron emission tomography (PET) and are outlined in this brief review.