Baseline Characteristics and 18F-FDG PET Findings in Present Patients
| Characteristic | All subjects (n = 50) | RI-SUV ≥ 0% (n = 27) | RI-SUV < 0% (n = 23) | P* |
| Sex (n) | 1.00 | |||
| Male | 42 | 23 | 19 | |
| Female | 8 | 4 | 4 | |
| Age (y) | 69.6 ± 9.7 | 69.8 ± 10.0 | 70.4 ± 9.0 | 0.88 |
| Follow-up period (mo)† | 29 (2–91) | 24 (2–80) | 57 (7–91) | 0.002 |
| Smoking status (n) | 0.79 | |||
| Non-smoker | 13 | 6 | 7 | |
| Ex-smoker | 25 | 14 | 11 | |
| Current-smoker | 12 | 7 | 5 | |
| Smoking amount (pack-years) | 34.6 ± 28.6 | 34.2 ± 26.1 | 35.0 ± 31.9 | 0.95 |
| Spirometry at baseline | ||||
| FVC (% predicted) | 84.1 ± 24.3 | 75.5 ± 22.4 | 94.3 ± 23.0 | 0.017 |
| DLCO (% predicted) | 56.6 ± 18.0 | 50.5 ± 18.3 | 63.6 ± 15.2 | 0.007 |
| Resting PaO2 (mm Hg) | 83.6 ± 13.4 | 80.5 ± 14.2 | 87.2 ± 11.7 | 0.087 |
| 6-min walk distance (m) | 370 ± 123 | 336 ± 129 | 410 ± 105 | 0.035 |
| 6-min walk test nadir SpO2 (%) | 89.1 ± 4.9 | 87.7 ± 5.5 | 90.7 ± 3.5 | 0.035 |
| Extent of fibrosis score (n) | 0.042 | |||
| 0 | 0 | 0 | 0 | |
| 1 | 15 | 4 | 11 | |
| 2 | 21 | 12 | 9 | |
| 3 | 13 | 10 | 3 | |
| 4 | 1 | 1 | 0 | |
| 18F-FDG PET findings | ||||
| Early SUV | 1.21 ± 0.43 | 1.36 ± 0.56 | 1.10 ± 0.25 | 0.20 |
| Delayed SUV | 1.22 ± 0.55 | 1.54 ± 0.65 | 0.92 ± 0.25 | 0.0002 |
| RI-SUV (%) | −0.34 ± 16.5 | 13.3 ± 6.8 | −16.3 ± 7.4 |