The Value of 18 F-FDG PET/CT in Evaluating Disease Severity and Prognosis in Idiopathic Pulmonary Fibrosis Patients

ABSTRACT

Background@#Several parameters are useful for assessing disease severity in idiopathic pulmonary fibrosis (IPF); however, the role of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) is not well-defined. We aimed to evaluate the value of 18 F-FDG PET/CT for assessing disease severity and prognosis in IPF patients. @*Methods@#Clinical data of 89 IPF patients (mean age 68.1 years, male 94%) who underwent18 F-FDG PET/CT for evaluation of lung nodules or cancer staging were retrospectively reviewed. Mean and maximal standardized uptake values (SUV mean , SUV max , respectively) were measured in the fibrotic area. Adjusted SUV, including SUV ratio (SUVR, defined as SUV max -to-liver SUV mean ratio), tissue fraction-corrected SUV mean (SUV meanTF ), and SUVR (SUVRTF ), and tissue-to-blood ratio (SUV max /SUV mean venous; TBR blood ) were obtained. Death was defined as the primary outcome, and associations between other clinical parameters (lung function, exercise capacity, C-reactive protein [CRP] level) were also investigated. @*Results@#All SUV parameters were inversely correlated with the forced vital capacity, diffusing capacity for carbon monoxide, and positively correlated with CRP level and the gender-agephysiology index. The SUV mean , SUV max , and SUV meanTF were associated with changes in lung function at six months. The SUVR (hazard ratio [HR], 1.738; 95% confidence interval [CI], 1.011–2.991), SUVR TF (HR, 1.441; 95% CI, 1.000–2.098), and TBR blood (HR, 1.377; 95% CI, 1.038–1.827) were significant predictors for mortality in patients with IPF in the univariate analysis, but not in the multivariate analysis. @*Conclusion@#18 F-FDG PET/CT may provide additional information on the disease severity and prognosis in IPF patients, and the SUVR may be superior to other SUV parameters.