18F-FDG Uptake in Less Affected Lung Field Provides Prognostic Stratification in Patients with Interstitial Lung Disease
Journal of Nuclear Medicine
This study evaluated the clinical significance of 18 F-FDG PET/CT in patients with interstitial lung disease (ILD), by investigating the relationships between 18 F-FDG PET/CT parameters and clinical indicators and by evaluating the prognostic implications of 18 F-FDG PET/CT results. Methods: Ninety patients (51 men, 39 women; mean age, 55.4 y; age range, 26-78 y) with ILD who underwent 18 F-FDG PET/CT were retrospectively analyzed. SUV mean was defined as the mean SUV of the less-affected lung
... less-affected lung field, SUV TF as adjusted SUV mean using tissue fraction (TF), and CT mean as the mean attenuation of the corresponding region of interest on highresolution CT. SUV mean , SUV TF , and CT mean were compared in the 90 ILD patients and in 15 age-and sex-matched controls. Correlations of SUV max , SUV mean , SUV TF , and CT mean with clinical indicators, including estimated percentage of forced vital capacity (%FVC), estimated percentage of diffusion capacity of the lungs for carbon monoxide (%DLco), sialylated carbohydrate antigen Krebs von den Lungen-6 (KL-6), surfactant protein D (SP-D), C-reactive protein (CRP), lactate dehydrogenase (LDH), and ILD-sex-agephysiology (GAP) index, were evaluated using the Spearman rank correlation test and the Tukey-Kramer test. A Cox proportional hazards model was used for univariate and multivariate analyses of factors associated with lung transplantation-free survival. Results: SUV mean , SUV TF , and CT mean were significantly higher in ILD patients than in healthy controls, except for CT mean in patients with a nonusual interstitial pneumonia pattern. SUV mean and CT mean were significantly correlated with %FVC, %DLco, KL-6, and SP-D; SUV TF was significantly correlated with %DLco, KL-6, SP-D, and LDH; and SUV max was weakly correlated with KL-6 and CRP. Univariate analysis showed that SUV mean , SUV TF , sex, %FVC, %DLco, KL-6, and ILD-GAP index were significantly prognostic of lung transplantationfree survival; and multivariate analysis showed that SUV mean and ILD-GAP index were independently prognostic of lung transplantationfree survival. A higher SUV mean indicated a poorer prognosis, especially in patients with moderate risk based on ILD-GAP index. Conclusion: SUV mean was significantly but moderately correlated with clinical indicators, providing independent prognostic information in patients with ILD. 18 F-FDG PET/CT may be helpful for monitoring and risk stratification of ILD patients.