Prognostic value of [18F]FDG PET/CT in patients with idiopathic pulmonary fibrosis

The study investigates the prognostic value of [F-18]fluorodeoxyglucose (FDG) PET/CT in patients with idiopathic pulmonary fibrosis (IPF). A total of 346 IPF patients who underwent FDG PET/CT between 2007 and 2020 were analyzed. Pulmonary FDG uptake [target to background ratio (TBR)] was binarized by optimal cut-off value based on survival analysis. The PET-modified GAP (Gender, Age, lung Physiology) score-based staging system included a category for FDG uptake, and its prognostic prediction was compared with the conventional GAP score. Survival analyses were conducted for progression-free, overall, and disease-specific survival. The low FDG uptake group showed a significantly better prognosis than the high uptake group, with cut-off values of 7.26 (p < 0.001), 7.15 (p = 0.04), and 9.23 (p = 0.01) for progression-free, overall, and disease-specific survival, respectively. The PET-modified GAP score-based staging system differentiated better than the conventional GAP system, particularly between stages I and II in overall survival (p = 0.001 vs. p = 0.08). For disease-specific survival, the PET-modified model showed better performance than the original GAP model (p = 0.06 vs. p = 0.33), though neither was statistically significant. Pulmonary FDG uptake in PET/CT is a reliable biomarker for predicting the prognosis of IPF patients and enhances the conventional GAP staging system's predictive value for patient survival.