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

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.