[The application of (18)F fluorodeoxyglucose-positron emission tomography/computed tomography in the diagnosis and treatment of dermatomyositis].

OBJECTIVE: To investigate the value of (18)F fluorodeoxyglucose-positron emission tomography/computed tomography ((18)F FDG-PET-CT) in the diagnosis and the evaluation of disease activity and remission of dermatomyositis(DM). METHODS: DM patients who were admitted to the Department of Rheumatology, the People's Liberation Army General Hospital (PLAGH) and underwent (18)F FDG-PET-CT examination were retrospectively reviewed from January 2012 to May 2015.Gender and age matched healthy controls (HC) were also enrolled.The standardized uptake value (SUV) of proximal limb girdle muscles in both groups were recorded and compared, so as between patients with DM or subclinical DM.The correlation between myodynamia of proximal limb girdle muscle, creatine kinase(CK), CK-MB, serum ferritin and SUV of each muscle group were analyzed. RESULTS: There were 58 patients with DM and 29 controls consecutively recruited in the study.The SUV of upper arms (1.814±0.830) g/ml, shoulders (2.134±0.797) g/ml and hips (1.883±0.683) g/ml in patients with classic DM were significantly higher than those with subclinical DM [(0.938±0.218) g/ml, (1.152±0.315) g/ml, (0.945±0.249) g/ml; P<0.05]. SUV of muscles in newly diagnosed patients was (1.051±0.031) g/ml, which was higher than that in subclinical patients.But the difference was not statistically significant (P>0.05). The average SUV of evaluated muscles in DM group (2.033±0.858) g/ml was significantly higher than that in controls (1.076±0.167) g/ml (P<0.001). Receiver operating characteristic(ROC) analysis revealed the area under the curve(AUC) of abnormal SUV detected by (18)F FDG-PET-CT for diagnosing DM was 0.953.The myodynamia of upper arms and SUV was negatively correlated (rs=-0.440, P=0.031). However, the level of serum creatine kinase and SUV was positively correlated (rs=0.500, P=0.013). The average SUV of patients whose time to remission was less than 3 months (1.746±0.466) g/ml was obviously less than that of patients with 3 to 6 months to obtain remission (2.815±0.848) g/ml (P=0.015). CONCLUSIONS: The SUV of proximal limb girdle muscles detected by (18)F FDG-PET-CT has a positive diagnostic value for DM.Moreover, the SUV in upper arms is correlated with the muscle strength and the level of creatine kinase, which reflect disease activity. (18)F FDG-PET-CT might be an alternative method to evaluate the response of treatment.