Predictive value of 18F-FDG PET/CT for anti-MDA5 antibody and prognosis of dermatomyositis / 中华核医学与分子影像杂志

ABSTRACT

Objective:To assess the imaging characteristics of muscle FDG metabolism, tumor incidence, and pulmonary interstitial changes in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody positivity in 18F-FDG PET/CT imaging, and the value of 18F-FDG PET/CT in differentiating anti-MDA5 antibody positive dermatomyositis. Methods:From June 2016 to July 2019, the PET/CT images of 75 patients with dermatomyositis (21 males, 54 females, age (52.3±14.3) years; 34 anti-MDA5 antibody positive and 41 anti-MDA5 antibody negative) and 30 healthy controls (10 males, 20 females; age (53.5±11.8) years) were retrospectively analyzed in Renji Hospital, School of Medicine, Shanghai Jiao Tong University. The SUV max of muscle was measured and the mean of SUV max (mSUV max) was calculated. Statistics of patients with dermatomyositis complicated with neoplastic lesions and the SUV max of pneumonia lesions in patients with dermatomyositis complicated with interstitial pneumonia was determined. Independent sample t test, one-way analysis of variance, Student-Newman-Keuls (SNK) test and χ2 test were used to analyze data. The ROC curve analysis was used to analyze the diagnostic efficacy of mSUV max for the differential diagnosis of anti-MDA5 antibody positive dermatomyositis. Results:The muscle mSUV max of the control group, anti-MDA5 antibody positive and negative groups were 0.39±0.05, 0.66±0.21 and 0.87±0.29 ( F=39.93, P<0.001), respectively. The muscle mSUV max of dermatomyositis patients was increased compared with healthy controls ( q values 6.76, 12.63, both P<0.001), and the muscle mSUV max of anti-MDA5 antibody negative was higher than positive ( q=5.79, P<0.001). The AUC was 0.74, and the cut-off value of muscle mSUV max was 0.75 with the accuracy of 74.7%(56/75). Of 41 patients with negative anti-MDA5 antibody, there were 6 (14.6%) had malignant tumor, while there was no malignant tumor in patients with positive anti-MDA5 antibody (0/34; χ2=5.41, P=0.020). There were 11 patients (26.8%, 11/41) with anti-MDA5 antibody negative dermatomyositis complicated with interstitial pneumonia and 33 patients (97.1%, 33/34) with anti-MDA5 antibody positive dermatomyositis complicated with interstitial pneumonia ( χ2=37.81, P<0.001). FDG metabolism in anti-MDA5 antibody positive patients was higher than that in anti-MDA5 antibody negative patients (lesion SUV max 3.65±1.83 and 2.38±1.27; t=2.13, P=0.039). Conclusions:The muscle FDG metabolism of anti-MDA5 antibody positive dermatomyositis patients is higher than that of healthy controls, but lower than that of anti-MDA5 antibody negative patients. The incidence of neoplastic lesions in patients with positive anti-MDA5 antibody is lower than that in patients with negative anti-MDA5 antibody. The proportion and severity of interstitial pneumonia are higher in patients with positive anti-MDA5 antibody than in those with negative anti-MDA5 antibody. 18F-FDG PET/CT has certain value on identifying anti-MDA5 antibody positive dermatomyositis.