Table 3

ApplicationsPopulation/animal modelsRadioligandMain findingsRef.

PreclinicalUnilateral instillation of fibrogenic (microcrystalline SiO2, rabbits), nonfibrogenic (amorphous SiO2, rabbits) 5 μm particles into rabbit lungs11C-PK11195Significantly increased tracer tissue/plasma ratios from day 3 after instillation in the challenged region, in both silica models, and remaining at least 2 weeks
In the amorphous silica model, an extrapulmonary TSPO PET signal appeared at 6 days
In the microcrystalline silica model, this extrapulmonary signal is delayed until 3 weeks after instillation
Jones et al. (2002) [91]

Clinical6 COPD patients, 6 chronic asthmatics, and 5 HC11C-PK11195Mean tracer uptake was higher in 4/6 COPD patients and 3/6 asthmatics than the maximum value in HC
No statistical correlation was found between binding tracer and either the magnitude of the 18F-FDG signal or the severity of the disease
Jones et al. (2003) [100]

Clinical15 FASSc (10 drug-naive & 5 with immunosuppressive drugs) patients versus 7 HC11C-PK11195Tracer lung uptake was decreased in FASSc patients, compared to normal controls
Strong negative correlation between tissue radioligand uptake and lung density in FASSc patients
Pulmonary tracer binding showed a nonsignificant but progressive decrease from normal in FASSc drug-naive patients to those patients immunosuppressive-treated
No significant correlation between tracer uptake and pulmonary function data
Branley et al. (2008) [85]

COPD, chronic obstructive pulmonary disease; FASSc, fibrosing alveolitis due to systemic sclerosis; HC, healthy control.