Quantification of hand muscle volume and composition in patients with rheumatoid arthritis, psoriatic arthritis and psoriasis

Friedberger et al. BMC Musculoskeletal Disorders https://doi.org/10.1186/s12891-020-03194-5 (2020) 21:203 RESEARCH ARTICLE Open Access Quantification of hand muscle volume and composition in patients with rheumatoid arthritis, psoriatic arthritis and psoriasis Andreas Friedberger1*, Camille Figueiredo2, Alexandra Grimm1, Isabelle d’Oliveira2, Tobias Bäuerle3, Jürgen Rech2, Arnd Kleyer2, David Simon2, Michael Uder3, Georg Schett2 and Klaus Engelke2 Abstract Background: Psoriasis (Pso), psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are inflammatory diseases. PsA and RA are characterized by bone and muscle loss. In RA, bone loss has been extensively characterized, but muscle loss has, to the best of our knowledge, not been quantified to date. Methods: A random forest based segmentation method was used to analyze hand muscle volume in T1 weighted MRI images of 330 patients suffering from Pso, PsA or RA. In addition, fat volume was quantified using MRI Dixon sequences in a small subset (n = 32). Results: Males had a higher relative muscle volume than females (14% for Pso, 11% for PsA, n.s. for RA). Between 40 and 80 years male Pso patients lost 13%, male PsA patients 16%, male RA patients 23% and female PsA patients 30% of their relative muscle volume. After adjustment for age, relative muscle volume in males RA patients was 16% and in female RA patients 9% lower than in Pso patients. In male RA patients relative muscle volume was 13% lower in than in male PsA patients. There was no difference in females. A significant negative correlation (R2 = 0.18) between relative intramuscular fat content relative hand muscle volume was observed. Conclusion: These preliminary data showed that relative hand muscle volume significantly decreased with age in male and female patients with Pso, PsA and RA patients. Independent of age, relative hand muscle volume was significantly smaller in patients with RA compared to the patients with Pso and the difference was twice as large in males compared to females. Also in male but not in female RA patients relative hand muscle volume was significantly smaller than in PsA patients. Keywords: Psoriasis, Psoriatic arthritis, Rheumatoid arthritis, Magnetic resonance imaging, Random forest based segmentation, Hand muscle, Fat * Correspondence: 1 Institute of Medical Physics, University of Erlangen-Nuremberg, Henkestraße 91, 91052 Erlangen, Germany Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Friedberger et al. BMC Musculoskeletal Disorders (2020) 21:203 Background Rheumatoid arthritis (RA) is a chronic inflammatory disease, which is associated with bone and cartilage loss [1]. About two thirds of RA patients also suffer from rheumatoid cachexia (RC) [1], an accelerated involuntary loss of fat-free skeletal muscle mass, which is larger than the decrease related to ‘normal’ aging (sarcopenia). The term RC has already been coined in 1992 [2], but etiology and pathophysiology of RC are still not well understood. RC is underdiagnosed and undertreated [3–5]. Structural bone damage of RA has been assessed using radiographs, magnetic resonance imaging (MRI) and more recently high resolution peripheral quantitative computed tomography (HR-pQCT). In contrast, techniques to quantify muscle properties are still under development. For the diagnosis of RC, advanced muscle and fat imaging is required. 85% of RA subjects have normal BMI [6] because the muscle loss is often compensated by fatty infiltration, resulting in normal body weight. Thus, the sole use of BMI for the diagnosis of RC is misleading. It has been suggested [7, 8] that the increased fatty infiltration may be one factor to explain the discrepancy of age related decreases between muscle mass and volume in healthy subjects [9]. In addition, adipose tissue is a source of pro-inflammatory cytokines, which triggers inflammatory responses [10, 11], an important observation with potentially high clinical relevance not only in RA but also in psoriatic arthritis (PsA) and psoriasis (Pso). Similar to RA, PsA is also characterized by inflammation of the synovial tissue, which ultimately results in bone, cartilage and muscle damage. However, the production and secretion of pro-inflammatory cytokines is lower than in RA [12, 13], which may explain why PsA is usually less destructive. Pso mainly affects the skin, but subclinical joint inflammation has also been reported [14, 15]. Nevertheless, to the best of our knowledge, no major impact of Pso on muscle has been reported so far. This study specifically addresses the assessment of hand muscle volume and composition in patients with rheumatoid, psoriatic arthritis and psoriasis using standard clinical and Dixon MRI sequences. The primary study aim was to compare hand muscle volume among the three diseases, independent of age and BMI. Additionally, preliminary results of a hand fat volume assessment were included. For the purpose of this study, psoriasis patients were used as controls. Methods Patient details In this study we used existing MRI scans of the dominant hand of 330 ambulatory care patients diagnosed with RA, PsA or Pso, from the Department of Medicine 3 of the University of Erlangen-Nuremberg. Apart from the Page 2 of 11 disease there were no additional inclusion or exclusion criteria. BMI data was available from 206 patients. This subset will be denoted as SBMI. MR imaging Routine MRI Scans were performed with a 1.5-Tesla MRI system (MAGNETOM Aera, Siemens Healthcare GmbH, Erlangen, Germany). Subjects were positioned in prone position with head first. For signal reception, a hand/wrist radiofrequency 16-channel coil was used. The standard clinical MR protocol included several sequences from which a fat suppressed T1w TSE was selected for analysis. More recently, a T2w Dixon TSE sequence has been added to the clinical protocol. The specifi (...truncated)