OP0213 MYOFASCIA-DOMINANT: INFLAMMATION DETECTED ON WHOLE BODY MRI PREDICTS RAPIDLY PROGRESSIVE INTERSTITIAL LUNG DISEASE IN PATIENTS WITH DERMATOMYOSITIS

Abstract

Background Rapidly progressive interstitial lung disease (RPILD) is a major cause of death in patients with dermatomyositis (DM). Early diagnosis and aggressive immunosuppressive therapy are required in RPILD to improve the prognosis. Clinically amyopathic dermatomyositis (CADM) and anti-melanoma differentiation-associated gene 5 antibody are known as the risk factors for RPILD. However, 70% of the patients with CADM do not develop RPILD1. Whole-body magnetic resonance imaging (WB-MRI) can detect inflammation of whole muscle and myofascia. Although recent studies have indicated that MRI could be useful for assessing disease activity2, the relation between MRI findings and RPILD has not been investigated. Objectives In this study, we assessed whether WB-MRI findings are related with RPILD in patients with DM. Methods This retrospective study comprised 33 patients with DM who underwent WB-MRI in our hospital before the initiation of treatment for myositis. Muscular and myofascial signal abnormalities were scored on 42 muscular groups. The ratio of myofascial score to muscular score (myofascia/muscle ratio) was calculated and used to evaluate myofascia-dominant inflammation. RPILD was defined as the acute onset and rapid worsening of dyspnea, hypoxemia and radiographic ILD/fibrosis within 1 month. Results Of 33 patients, 16 were CADM, and 24 had ILD, including 8 patients with RPILD. All patients including CADM showed abnormal signal intensity in muscle and myofascia (scores median: 15 and 21, respectively). Muscle scores positively correlated with serum level of creatine kinase (r=0.672, p 1.53 (odds ratio: 141.90, p=0.042) and older age (odds ratio: 1.15, p=0.041) as independent risk factors for RPILD. Conclusion We newly defined myofascia-dominant inflammation using WB-MRI as a predictor to develop RPILD in patients with dermatomyositis.