Molecular imaging of inflammation with PET in acute and ventilator-induced lung injury

This review focuses on methods to image acute lung inflammation with Positron Emission Tomography (PET). Four approaches are discussed that differ for biologic function of the PET reporter probe, radiotracer employed, and the specific aspect of the inflammatory response that is targeted. 2-[F-18]fluoro-2-deoxy-D-glucose ([F-18]FDG) is an enzyme substrate whose uptake is used to measure the metabolic activation of inflammatory cells during acute lung injury in the noncancerous lung. H-2 O-15 and radiolabeled plasma proteins are inert molecules with the same physical characteristics as their nonradioactive counterparts and are used to measure edema and vascular permeability. Tagged enzyme or receptor inhibitors are used to probe expression of these targets induced by inflammatory stimuli. Lastly, cell-specific tracers are being developed to differentiate the cell types that contribute to the inflammatory response. Taken together, these methods cast PET imaging as a versatile and quantitative tool to measure inflammation in vivo noninvasively during acute and ventilator-induced lung injury.

Automated summary

This review discusses four different methods to image acute lung inflammation with Positron Emission Tomography (PET), which differ in terms of the PET reporter probe, radiotracer, and the specific aspect of the inflammatory response targeted. These methods include measuring metabolic activation of inflammatory cells using 2-[F-18]fluoro-2-deoxy-D-glucose ([F-18]FDG), measuring edema and vascular permeability using H-2 O-15 and radiolabeled plasma proteins, probing expression of targets induced by inflammatory stimuli using tagged enzyme or receptor inhibitors, and developing cell-specific tracers to differentiate cell types contributing to the inflammatory response. Overall, PET imaging proves to be a versatile and quantitative tool for noninvasively measuring inflammation during acute and ventilator-induced lung injury.