• idiopathic inflammatory myopathies
• interstitial lung disease
• lung CT

This was a retrospective study with the aim of defining the radiological characteristics of interstitial lung disease (ILD) in different serological groups of idiopathic inflammatory myopathies (IIM) patients, with semiquantitative and quantitative analysis of lung CT.
Ninety-eight patients with baseline CT and pulmonary function tests (PFTs) were included and divided in subgroups, based on their antibody pattern: anti-MDA5 (Group 1), anti-ARS (Group 2) and negative (Group 3).
For each CT the total score of Warrick (WS) was obtained at semiquantitative analysis; the scores ILD% (interstitial lung disease %) and PVRS% (pulmonary vascular related structure) were the result of quantitative analysis (CALIPER).
Positive correlations between WS, ILD% and PVRS% and inverse correlations between WS, ILD%, PVRS% and TLC%, DLCO% were found (P-value<0,05), the most relevant between ILD% and PVRS% (Rho=0,916; P-value=0,00) and ILD% and DLCO% (Rho=-0,590; P-value=0,00).
Statistically significant higher values of WS, ILD% and PVRS% were found in Group 1 (WS=15, ILD%=15, PVRS%=4.8) and Group 2 (WS=15, ILD%=11 and PVRS%=3.5), compared to Group 3 (WS=4, ILD%=0,85 and PVRS%=2.2).
In conclusion: the inverse correlations between the radiological scores and TLC% and DLCO% confirm the role of lung CT in the diagnosis of ILD in IIM patients.
For the first time anti-ARS, anti-MDA5 and serological negative patients were defined through semiquantitative and quantitative analysis of lung CT.