Objective. To elucidate the 18F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) characteristics and its prognostic value in anti-melanoma differentiation associated protein 5 antibody positive (anti-MDA5+) dermatomyositis (DM) patients. Methods. This retrospective cross-sectional study included 26 anti-MDA5+ DM patients and 43 anti-MDA5 negative (anti-MDA5-) idiopathic inflammatory myopathy (IIM) patients who were examined by 18F-FDG PET/CT from January 1st 2017 to December 31st 2020. The maximum standardized uptake value (SUVmax) of multiple organs and other clinical characteristics of patients were measured and analyzed. Results. Compared with the anti-MDA5- group, patients in the anti-MDA5+ group showed higher bilateral lung SUVmax (p=0.029), higher SUVmax of spleen (p=0.011) and bone marrow (p=0.048). Significant correlations between the spleen SUVmax and serum ferritin levels (r = 0.398, p <0.001), ESR (r = 0.274, p= 0.023), platelet count (r= − 0.265, p= 0.028), myositis disease activity assessment score (r = 0.332, p = 0.005), bone marrow SUVmax (r=0.564, p<0.001) and bilateral lung SUVmax (r=0.393, p<0.001) were as well observed. Conclusion. 18F-FDG PET/CT was found valuable in quantifying the pulmonary focal inflammation and potentially unveil the distinctive characteristics and pathophysiological mechanisms in anti-MDA5+ DM patients.

Radiological Characteristics of Patients With Anti-MDA5–Antibody-Positive Dermatomyositis in 18F-FDG PET/CT: A Pilot Study

Anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis (MDA5+ DM) is an infrequent autoimmune disease, which mainly distributes in Asians and females. MDA5+ DM usually presents various skin lesions and positive anti-MDA5 antibody (a myositis-specific autoantibody for itself) with amyopathic or hypomyopathic features. For MDA5+ DM patients, rapidly progressive interstitial lung disease is a common complication with a high-speed deterioration and a poor prognosis. Besides, there are other complications of MDA5+ DM patients, including pneumomediastinum, macrophage activation syndrome and spontaneous intramuscular hemorrhage. These complications were rare but lethal, so it is necessary to explore their diagnosis methods, therapies and potential mechanisms, which are helpful for early diagnoses and timely treatment. To date, several cases and studies have shown distinctive features, diagnoses and treatments of these three rare complications, and there are also some differences among them. In this review, we outlined the characteristics, administration and potential pathogenesis of these rare complications of MDA5+ DM.

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Rare complications of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: Time to nip them in the bud

18F-FDG PET/CT and HRCT: a combined tool for risk stratification in idiopathic inflammatory myopathy-associated interstitial lung disease

Imaging is an important tool in the evaluation of idiopathic inflammatory myopathies. It plays a role in diagnosis, assessment of disease activity and follow-up, and as a non-invasive biomarker. Among the different modalities, nuclear magnetic resonance imaging (MRI), ultrasound (US), and positron emission tomography (PET) may have the most clinical utility in myositis. MRI is currently the best modality to evaluate skeletal muscle and provides excellent characterization of muscle edema and fat replacement through the use of T1-weighted and T2-weighted fat suppressed/STIR sequences. Although MRI can be read qualitatively for the presence of abnormalities, a more quantitative approach using Dixon sequences and the generation of water T2 parametric maps would be preferable for follow-up. Newer protocols such as diffusion-weighted imaging, functional imaging measures, and spectroscopy may be of interest to provide further insights into myositis. Despite the advantages of MRI, image acquisition is relatively time-consuming, expensive, and not accessible to all patients. The use of US to evaluate skeletal muscle in myositis is gaining interest, especially in chronic disease, where fat replacement and fibrosis are detected readily by this modality. Although easily deployed at the bedside, it is heavily dependent on operator experience to recognize disease states. Further, systematic characterization of muscle edema by US is still needed. PET provides valuable information on muscle function at a cellular level. Fluorodeoxyglucose (FDG-PET) has been the most common application in myositis to detect pathologic uptake indicative of inflammation. The use of neurodegenerative markers is now also being utilized for inclusion body myositis. These different modalities may prove to be complementary methods for myositis evaluation. 

Muscle imaging in myositis: MRI, US, and PET.

Novel tracers for molecular imaging of interstitial lung disease: A state of the art review.

Background Interstitial lung disease (ILD) and its rapid progression (RP) are the main contributors to unfavourable outcomes of patients with idiopathic inflammatory myopathy (IIM). This study aimed to identify the clinical value of PET/CT scans in IIM-ILD patients and to construct a predictive model for RP-ILD. Methods Adult IIM-ILD patients who were hospitalized at four divisions of the First Affiliated Hospital, Zhejiang University School of Medicine (FAHZJU), from 1 January 2017 to 31 December 2020 were reviewed. PET/CT scans and other characteristics of patients who met the inclusion and exclusion criteria were collected and analysed. Results A total of 61 IIM-ILD patients were enrolled in this study. Twenty-one patients (34.4%) developed RP-ILD, and 24 patients (39.3%) died during follow-up. After false discovery rate (FDR) correction, the percent-predicted diffusing capacity of the lung for carbon monoxide (DLCO%, P = 0.014), bilateral lung mean standard uptake value (SUVmean, P = 0.014) and abnormal mediastinal lymph node (P = 0.045) were significantly different between the RP-ILD and non-RP-ILD groups. The subsequent univariate and multivariate logistic regression analyses verified our findings. A "DLM" model was established by including the above three values to predict RP-ILD with a cut-off value of ≥ 2 and an area under the curve (AUC) of 0.905. Higher bilateral lung SUVmean (P = 0.019) and spleen SUVmean (P = 0.011) were observed in IIM-ILD patients who died within 3 months, and a moderate correlation was recognized between the two values. Conclusions Elevated bilateral lung SUVmean, abnormal mediastinal lymph nodes and decreased DLCO% were significantly associated with RP-ILD in IIM-ILD patients. The "DLM" model was valuable in predicting RP-ILD and requires further validation.

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The lungs were on fire: a pilot study of 18F-FDG PET/CT in idiopathic-inflammatory-myopathy-related interstitial lung disease

Background: Secondary haemophagocytic lymphohistiocytosis (sHLH) is a rare but fatal complication in idiopathic inflammatory myopathy (IIM) patients. The clinical value of radiological manifestations and serum cytokines remain unknown in this systemic crisis. This study aims to investigate the clinical value of PET/CT scan and cytokine profiles in predicting and understanding sHLH in IIM patients. Methods: Adult IIM patients who were admitted to the four divisions of the First Affiliated Hospital, Zhejiang University School of Medicine (FAHZJU) from January 1st 2017 to December 31st 2020 were reviewed. PET/CT scan, cytokine profiles as well as other factors of patients who met the inclusion and exclusion criteria were collected and analyzed. Results: Sixty-nine out of 352 IIM patients were finally enrolled into the study. Ten patients developed sHLH and 70.0% of them died within six months. After false discovery rate (FDR) correction and multivariate logistic regression analysis, increased serum interferon (IFN)-γ level (P=0.017) higher spleen mean standard uptake value (SUVmean, P=0.035) and positivity of anti-MDA5 antibody (P=0.049) were found to be significantly correlated with development of sHLH in IIM patients. The combination of serum IFN-γ, spleen SUVmean and anti-MDA5 antibody was found a balanced and satisfying predictor with a cut-off value of 0.047 and AUC of 0.946. A moderate correlation was identified between ferritin and spleen SUVmean (P=0.001, r=0.380) as well as serum IFN-γ(P=0.001, r=0.398). Before FDR correction, higher bilateral lung SUVmean (P=0.034), higher colon/rectum SUVmean (P=0.013) were also observed in IIM patients who developed sHLH. By narrowing down to IIM patients with sHLH, anti-MDA5-antibody-positive DM patients tended to suffer from unfavorable outcome (P=0.004) in Kaplan-Meier survival analysis. Conclusion: Increased serum level of IFN-γ, elevated splenic FDG uptake and positivity of anti-MDA5 antibody were significantly correlated with development of sHLH in IIM patients. Lung and lower digestive tract might also be affected due to systemic immune activation in IIM patients with sHLH. In addition, splenic FDG uptake, in combination with serum IFN-γand anti-MDA5 antibody, was found valuable in predicting development of sHLH in IIM patients. Among IIM patients with sHLH, anti-MDA5-antibody-positive DM patients showed higher tendency for unfavorable outcome.

Clinical Value of 18F-FDG PET/CT Scan and Cytokine Profiles in Secondary Hemophagocytic Lymphohistiocytosis in Idiopathic Inflammatory Myopathy Patients: A Pilot Study

Bingjue Ye

Papers

The lungs were on fire: a pilot study of 18F-FDG PET/CT in idiopathic-inflammatory-myopathy-related interstitial lung disease

Clinical Value of 18F-FDG PET/CT Scan and Cytokine Profiles in Secondary Hemophagocytic Lymphohistiocytosis in Idiopathic Inflammatory Myopathy Patients: A Pilot Study