Quantification of regional murine ozone-induced lung inflammation using [18F]F-FDG microPET/CT imaging

Abstract

Ozone (O3) is a highly potent and reactive air pollutant. It has been linked to acute and chronic respiratory diseases in humans by inducing inflammation. Our studies have found evidence that 0.05 ppm of O3, within the threshold of air quality standards, is capable of inducing acute lung injury. This study was undertaken to examine O3-induced lung damage using [18F]F-FDG (2-deoxy-2-[18F]fluoro-D-glucose) microPET/CT in wild-type mice. [18F]F-FDG is a known PET tracer for inflammation. Sequential [18F]F-FDG microPET/CT was performed at baseline (i.e. before O3 exposure), immediately (0 h), at 24 h and at 28 h following 2 h of 0.05 ppm O3 exposure. The images were quantified to determine O3 induced spatial standard uptake ratio of [18F]F-FDG in relation to lung tissue density and compared with baseline values. Immediately after O3 exposure, we detected a 72.21 ± 0.79% increase in lung [18F]F-FDG uptake ratio when compared to baseline measures. At 24 h post-O3 exposure, the [18F]F-FDG uptake becomes highly variable (S.D. in [18F]F-FDG = 5.174 × 10–4 units) with a 42.54 ± 0.33% increase in lung [18F]F-FDG compared to baseline. At 28 h time-point, [18F]F-FDG uptake ratio was similar to baseline values. However, the pattern of [18F]F-FDG distribution varied and was interspersed with zones of minimal uptake. Our microPET/CT imaging protocol can quantify and identify atypical regional lung uptake of [18F]F-FDG to understand the lung response to O3 exposure.