Objectives This study examined contributions of deep inspiratory breath hold (DIBH) -FDG-PET/CT to clinical assessment of ILD in collagen diseases.

Methods We assessed ILD in 45 patients with collagen diseases including 6 RA, 9 SSc, and 17 DM/PM by using DIBHPET/CT. Distribution of positive signals was evaluated in the upper slice 2cm above the tracheal bifurcation, the middle slice 1 cm below the bifurcation, and the lower slice 2 cm above the right diaphragm. Individual slices were further divided into 6 regions. Visual score was determined by numbers of positive signal lesions in total 18 regions.

Results Abnormal accumulation of FDG was found in the active ILD lesions which were concordant with nodular, reticular, consolidative shadows and ground glass opacity illustrated by plain CT scan. The visual score in the lesions was well correlated with serum levels of KL-6 (Pearson ρ=0.571, P=0.011) and CRP (Spearman ρ=0.506, P=0.016). The value was significantly higher in 26 patients who were judged as being clinically active than the other 19 patients.

Of 24 patients who had follow-up examinations, abnormal FDG accumulation was reduced in response to the therapies in 11 patients, whereas the findings were unchanged or deteriorated in the remaining 13 patients who had stable or progressive ILD. In spite of no interval change in plain CT scan, PET/CT detected significant changes of FDG intensity in the follow-up studies in 5 patients. FDG signal was reduced in 4 of them, whereas it was increased in one patient.

Conclusions In summary, DIBH PET/CT is useful for monitoring of activity in collagen disease associated ILD.

Disclosure of Interest None Declared