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

Idiopathic inflammatory myopathies related lung disease in adults

Interstitial lung disease (ILD) is common in idiopathic inflammatory myopathies in adults, especially in patients with antisynthetase syndrome and anti-MDA5 antibody-associated dermatomyositis. Pulmonary manifestations can range from subclinical ILD to rapidly progressive respiratory failure. Coexistent myositis, characteristic skin lesions, arthritis, and Raynaud's phenomenon are common. However, 16-65% of patients present with isolated lung disease. Detection of myositis-specific and myositis-associated antibodies can aid in diagnosis and disease characterisation. Chest imaging and pathology most commonly show non-specific interstitial pneumonia and organising pneumonia patterns. Immunosuppression is the mainstay of management with aggressive combination treatment for rapidly progressive disease and incremental escalation as needed for chronic ILD. The addition of antifibrotic agents is an option in progressive fibrotic disease, and lung transplantation can be considered in severe, end-stage disease. Most patients respond to treatment, but short-term mortality remains high for patients with rapidly progressive disease associated with anti-MDA5 antibody ILD.

A nomogram for the prediction of co-infection in MDA5 dermatomyositis: A rapid clinical assessment model

BACKGROUND

Patients with anti-melanoma differentiation-associated gene 5-positive dermatomyositis (MDA5 DM) are prone to infections, but there is a lack of rapid methods to assess infection risk, which greatly affects patient prognosis. This study aims to analyze the clinical features of MDA5 DM patients systematically and develop a predictive model for infections.

METHODS

Retrospective analysis was performed on clinical data from 118 hospitalized patients with MDA5 DM. According to the results of pathogen detection and clinical manifestations, the patients were divided into infected group and non-infected group. LASSO analysis and multivariate logistic regression were used to establish the prediction model of infection in MAD5 DM patients. The resulting model was visualized using a Nomogram. We used methods such as Receiver Operating Characteristic (ROC) curve analysis, Area Under the Curve (AUC) calculation to evaluate the model.

RESULT

The Cough, interstitial lung disease, moist rales, positive anti-RO-52, carcinoembryonic antigen, triglyceride, hydroxybutyrate dehydrogenase and erythrocyte sedimentation rate were significantly associated with infection risk in MDA5 DM patients. A prediction model was developed using these eight risk factors, achieving an AUC of 0.851 in determining co-infection status. Further analysis based on infection site and pathogen classification demonstrated strong discrimination performance of the model in identifying pulmonary infection (AUC: 0.844) and fungal infection (AUC: 0.822).

CONCLUSION

This study aimed to develop a clinical prediction model and visualize it using Nomogram to assess the risk of infection in MDA5 DM. The model provides an effective tool for determining infection status in patients and serves as a reference for formulating clinical medication regimens.

Muscle Function, Muscle Disease, and Positron Emission Tomography-Computed Tomography: A Narrative Review

18F-fluorodeoxyglucose (18F-FDG) is a radiopharmaceutical that exhibits glucose-like kinetics and is used in positron emission tomography (PET). 18F-FDG is used for cancer diagnosis in clinical practice. However, 18F-FDG uptake is also observed in normal organs, such as the brain, liver, and heart, with high glucose consumption. Moreover, 18F-FDG uptake is also observed in muscles, where its accumulation and radioactivity reflect muscle activity. Dystonia is characterized by excessive muscle movement. Recently, 18F-FDG and technetium-99m-methoxyisobutyl isocyanide ([99mTc]MIBI) have been used for the diagnosis and botulinum toxin therapy evaluation of dystonia. This review aimed to summarize the utility of 18F-FDG-PET for the evaluation of muscle activity and diagnosis of muscle diseases such as dystonia, polymyositis, dermatomyositis, and polymyalgia rheumatica.

Radiation Toxicity in MDA5+ and PL7-Positive Dermatomyositis: Heightened Risk in Autoimmune Subtypes

Purpose

To increase awareness of peri-radiation therapy (RT) intervention that may unduly heighten the risk of toxicity in lung cancer patients and encourage molecular testing and pretreatment consultation with rheumatology for patients with active autoimmune conditions.

Materials and Methods

A 42-year-old male with an autoimmune disease was diagnosed with non-small cell lung cancer. He received 4 cycles of pemetrexed/cisplatin with proton therapy (PT) delivered halfway through for a bronchial stump positive margin. After completing the first cycle of adjuvant chemotherapy, he was given 61.6 Gy in 28 fractionations of PT. Before restarting chemotherapy, he experienced a dry cough and later shortness of breath (SOB), which resolved with an aggressive steroid taper. After completing his third cycle of cisplatin/pemetrexed, his SOB and cough worsened. He was admitted for an urgent bronchoscopy with debridement of the distal trachea and proximal left main bronchus. He received high-dose steroids again and another bronchoscopy, revealing a tracheoesophageal fistula. Rheumatology identified an MDA5+ and PL7-positive dermatomyositis subtype at this time, known to be associated with rare ulcerative symptoms.

Results

A rare MDA5+ and PL7-positive dermatomyositis subtype, discovered post treatment, most likely contributed to SOB and cough following chemotherapy and PT, resulting in bronchoscopy of the irradiated field. A combination of these factors may have contributed to the tracheoesophageal fistula.

Conclusion

Patients with autoimmune disease should be carefully evaluated for rare underlying subtypes that could pose a danger to treatment. Oncologists should continue to be vigilant about underlying genetic predisposing factors that lead to exacerbated toxicity. Immunosuppressive agents given with RT may be considered for patients with autoimmune disease. Avoidance of biopsy, tissue manipulation, debridement, or any form of soft-tissue or hard-tissue violation needs to be discussed across the multidisciplinary spectrum to avoid nonhealing lesions shortly after RT.

Imaging Modalities in Myositis: A Clinical Review

This review highlights the key role of imaging modalities in diagnosing and managing myositis. The authors underscore MRI's superiority in identifying muscle edema and fat infiltration, marking it as essential for evaluating disease activity and damage. They also suggest ultrasound's emerging significance for diagnosis and monitoring of the disease, valued for its ease of use, and real-time capabilities. Furthermore, PET scans' unique physiologic capabilities, especially useful for malignancy detection and assessing lung disease, are emphasized. Collectively, these imaging techniques offer a tailored approach to myositis management, facilitate precise diagnosis, effective treatment planning, and disease activity monitoring, thereby enhancing patient outcomes in rheumatology practice.

Multivariate logistic regression analysis of poor prognosis of dermatomyositis and clinical value of ferritin/Kl-6 in predicting prognosis

BACKGROUND

Dermatomyositis (DM) is a rare inflammatory disease. Our research focuses on predicting poor prognosis in DM patients and evaluating the prognostic significance of ferritin and Salivary Sugar Chain Antigen-6 (KL-6) through multivariate logistic regression analysis.

METHODS

Between February 2018 and April 2020, 80 DM patients at our hospital were categorized into MDA5 positive (n = 20) and negative (n = 60) groups. We conducted multivariate logistic regression to determine DM's poor prognosis risk factors and evaluate ferritin/KL-6's predictive value for prognosis.

RESULTS

Analysis showed no gender, age, body mass index (BMI), or lifestyle (smoking, drinking) differences, nor in dyspnea, muscle weakness, skin ulcers, and acetylcysteine treatment effects (p > 0.05). Significant differences emerged in arrhythmias, interstitial pneumonia, C-reactive protein, albumin, and lactate dehydrogenase levels (p < 0.05). Before treatment, differences were negligible (p > 0.05), but post-treatment, serum KL-6 and ferritin levels dropped. MDA5 positive patients had elevated serum KL-6 and ferritin levels than survivors (p < 0.05), with a strong correlation to DM. Combined diagnosis using serum KL-6 and ferritin for DM prognosis showed area under curves of 0.716 and 0.634, significantly outperforming single-index diagnoses with an area under curve (AUC) of 0.926 (p < 0.05).

CONCLUSION

Serum KL-6 and ferritin show marked abnormalities in DM, useful as indicators for evaluating polymyositis and DM conditions. However, the study's small sample size is a drawback. Expanding the sample size is essential to monitor serum KL-6 and ferritin changes in DM patients under treatment more closely, aiming to improve clinical assessment and facilitate detailed research.

[18F]FDG-PET/CT in Idiopathic Inflammatory Myopathies: Retrospective Data from a Belgian Cohort

[¹⁸F]FDG-PET/CT is a useful tool for diagnosis and cancer detection in idiopathic inflammatory myopathies (IIMs), especially polymyositis (PM) and dermatomyositis (DM). Data deriving from Europe are lacking. We describe [¹⁸F]FDG-PET/CT results in a Belgian cohort with IIMs, focusing on patients with PM and DM. All of the cases of IIMs admitted between December 2010 and January 2023 to the Cliniques Universitaires Saint-Luc (Belgium) were retrospectively reviewed. In total, 44 patients were identified with suspected IIMs; among them, 29 were retained for final analysis. The mean age of the retained patients was 48.7 years; 19 patients were female (65.5%). Twenty-two patients had DM and seven had PM. The mean serum creatinine kinase (CK) and the mean CRP levels were 3125 UI/L and 30.3 mg/L, respectively. [¹⁸F]FDG-PET/CT imaging was performed for 27 patients, detecting interstitial lung diseases (ILDs) in 7 patients (25.9%), cancer in 3 patients (11.1%), and abnormal muscle FDG uptake compatible with myositis in 13 patients (48.1%). All of the patients who were detected to have ILDs via PET/CT imaging were confirmed using a low-dose lung CT scan. Among the patients who were detected to have abnormal muscle FDG uptake via PET/CT scans (13/28), the EMG was positive in 12 patients (p = 0.004), while the MRI was positive in 8 patients (p = 0.02). We further observed that there was a significantly higher level of CK in the group with abnormal muscle FDG uptake (p = 0.008). Our study showed that PET/CT is useful for detecting cancer and ILDs. We showed that the detection of abnormal muscle uptake via PET/CT was in accordance with EMG and MRI results, as well as with the mean CK value, and that the presence of dyspnea was significantly associated with the presence of ILDs detected via PET/CT imaging (p = 0.002).

Predictors of progression in idiopathic inflammatory myopathies with interstitial lung disease

The idiopathic inflammatory myopathies (IIMs) are a group of connective tissue diseases that afect multiple organ systems, including the lungs. Interstitial lung disease (ILD) is the most common and heterogeneous complication of IIMs, with its degree ranging from mild to fatal. Thus, it is critical to identify clinical features and validated biomarkers for predicting disease progression and prognosis, which could be beneficial for therapy adjustment. In this review, we discuss predictors for rapid progression of IIM-ILD and propose guidance for disease monitoring and implications of therapy. Systematic screening of myositis-specific antibodies, measuring serum biomarker levels, pulmonary function tests, and chest high-resolution computer tomography will be beneficial for the evaluation of disease progression and prognosis.

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

OBJECTIVES

Rapidly progressive interstitial lung disease (RP-ILD) is a life-threatening form of idiopathic inflammatory myopathy (IIM)-associated interstitial lung disease (ILD). We aimed to assess the combination of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) and high-resolution computed tomography (HRCT) for the quantification of IIM-ILD activity and risk stratification for RP-ILD.

METHOD

Patients with IIM and undergoing ¹⁸F-FDG PET/CT were included in this retrospective study. Pulmonary FDG uptake was assessed using the maximum standardized uptake value (SUV_lung) and visual score (PET score). HRCT was evaluated using visual analysis (HRCT score). Multivariable logistic regression was used to identify risk factors for RP-ILD.

RESULTS

Seventy-three patients with IIM (17 with RP-ILD, 38 with non-RP-ILD, and 18 without ILD) were included. SUV_lung, PET score, and HRCT score were significantly higher in RP-ILD than in non-RP-ILD. Strong positive correlations were observed between SUV_lung, PET score, and the HRCT parameters. The area under the curve (AUC) of the PET score to differentiate between RP-ILD and non-RP-ILD (AUC = 0.860) was higher than that of the SUV_lung (AUC = 0.802) and HRCT scores (AUC = 0.806). We developed a risk score based on the number of positive risk factors (PET score > 18, HRCT score > 140, and positive anti-melanoma differentiation-associated gene 5 (MDA5) antibody) to differentiate between RP-ILD and non-RP-ILD (AUC = 0.955). Patients with higher risk scores had significantly worse prognoses.

CONCLUSIONS

¹⁸F-FDG PET/CT is useful for assessing disease activity in patients with IIM-ILD. The combination of PET score, HRCT score, and anti-MDA5 antibody can be used to identify patients at increased risk of RP-ILD and with poor prognoses.

Muscle imaging in myositis: MRI, US, and PET

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.

The Role of Quantitative and Semi-quantitative [18F]FDG-PET/CT Indices for Evaluating Disease Activity and Management of Patients With Dermatomyositis and Polymyositis

Idiopathic inflammatory myopathies (IIM) are considered systemic diseases involving different organs and some subtypes are associated with increased cancer risk. In this review, we provide a comprehensive summary of the current use and potential applications of (semi-)quantitative [18F]FDG-PET/CT indices in patients with IIM focusing on dermatomyositis and polymyositis. Visual interpretation and (semi-)quantitative [18F]FDG-PET indices have a good overall performance to detect muscle activity but objective, robust and standardized interpretation criteria are currently lacking. [18F]FDG-PET/CT is a suitable modality to screen for malignancy in patients with myositis and may be a promising tool to detect inflammatory lung activity and to early identify patients with rapidly progressive lung disease. The latter remains to be determined in large, prospective comparative trials.