18FDG PET-CT standardized uptake value for the prediction of radiation pneumonitis in patients with lung cancer receiving radiotherapy.

The present study aimed to determine if the standardized uptake value (SUV) determined with 18F-FDG PET-CT can be used to predict radiation pneumonitis (RP) in lung cancer patients who receive radiotherapy. A total of 40 patients with non-small cell lung cancer received 18F-FDG PET-CT examinations prior to and following radiotherapy. The average SUV of lung tissue prior to and following radiation were measured at differing radiation doses. SUV differences between patients with and without RP, and the SUV ratio of the irradiated lung tissues compared with that of non-irradiated lung tissues (L/B) were compared. There were no differences in the mean SUV between the RP and no RP groups prior to radiotherapy. There were also no significant differences in the mean SUV of lung tissue within groups or between the no RP and RP groups with radiation doses of <5 Gy, 5 to ≤14.9 Gy and 15 to ≤34.9 Gy (all P>0.05) following radiotherapy. There were, however, statistically significant differences in the mean SUV of lung tissue within groups or between the no RP and RP groups with doses of ≥60 Gy prior to therapy and 35 to ≤59.9 Gy and ≥60 Gy following therapy (all P<0.05). When the L/B ratio was ≥3, the incidence of RP was 50%, and when the L/B ratio was ≥2.5 the incidence was 40.7%. When the L/B ratio was <2, there were no cases of RP. In conclusion, the present study indicates that 18F-FDG PET-CT can be used to predict RP by L/B ratio.