Positron emission tomography: a tool for better understanding of ventilator-induced and acute lung injury

PET has recently gained traction among several groups of investigators as an imaging tool to study lung pathophysiology in vivo noninvasively on a regional basis. This review aims to present the major findings of PET studies on acute lung injury (ALI) and ventilator-induced lung injury (VILI) with a perspective relevant to the physiologist-intensivist.

Using various tracers, PET has been used to investigate the relationship between the distributions of pulmonary perfusion, ventilation and aeration, and the effect of positive end-expiratory pressure, recruitment maneuvers, prone positioning, and endotoxin on these distributions in ALI. More recently, PET with 2-[18F]fluoro-2-deoxy-D-glucose has been used to measure regional neutrophil metabolic activation in ALI and VILI. Because gas exchange impairment and inflammation are two hallmarks of ALI and VILI, these studies have provided significant insights into the pathophysiology of these conditions.

PET is a versatile imaging tool for physiologic investigation. By imaging the regional effects of interventions commonly performed in critically ill patients with ALI, PET has improved our understanding of the mechanism by which such interventions can exert their positive or negative effects as well as of the pathophysiology of ALI and VILI.