Subclinical involvement of the trunk muscles in idiopathic inflammatory myopathies

Nozomu Matsuda; Shunsuke Kobayashi; Osamu Hasegawa; Kenji Yoshida; Hitoshi Kubo; Yoshikazu Ugawa; Kazuaki Kanai

doi:10.1177/20584601221075796

Subclinical involvement of the trunk muscles in idiopathic inflammatory myopathies

Acta Radiol Open. 2022 Feb 28;11(2):20584601221075796. doi: 10.1177/20584601221075796. eCollection 2022 Feb.

Authors

Nozomu Matsuda¹, Shunsuke Kobayashi², Osamu Hasegawa³, Kenji Yoshida¹, Hitoshi Kubo^{4

5}, Yoshikazu Ugawa⁶, Kazuaki Kanai¹

Affiliations

¹ Department of Neurology, Fukushima Medical University, Fukushima, Japan.
² Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan.
³ Department of Radiology and Nuclear Medicine, Fukushima Medical University, Fukushima, Japan.
⁴ Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan.
⁵ Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan.
⁶ Department of Human Neurophysiology, Fukushima Medical University, Fukushima, Japan.

Abstract

Background: Whole-body magnetic resonance imaging (WB-MRI) is a useful tool for revealing the disease-specific distribution of affected muscles and clinically asymptomatic muscle involvements in idiopathic inflammatory myopathies (IIMs).

Purpose: To examine inflammatory changes in the systemic skeletal muscles, including the thoracoabdominal trunk, in IIMs using WB-MRI.

Material and methods: We prospectively obtained WB-MRI axial images from 10 patients with IIMs, including antisynthetase syndrome (ASS), immune-mediated necrotizing myopathy (IMNM), sporadic inclusion body myositis, and myopathy associated with antimitochondrial antibody. We evaluated 108 systemic skeletal muscles in short-tau inversion recovery (STIR) images and rated changes in signal intensity using a semiquantitative scale. Correlations between STIR sum score, peak creatine kinase (CK) and muscle strength were examined. We also investigated the correlation between STIR sum score within the thoracoabdominal trunk and forced vital capacity.

Results: High STIR signal changes were frequently identified in asymptomatic and routinely unexamined muscles. Thoracoabdominal trunk muscles were frequently involved in ASS and IMNM. Peak CK was positively correlated with the STIR sum score (R ² = 0.62, p < .01). There was no significant correlation between the STIR sum score within the thoracoabdominal trunk and forced vital capacity.

Conclusion: WB-MRI can detect subclinical muscle inflammation in the systemic muscles including the trunk muscles. STIR sum score is positively correlated with serum peak CK level; therefore, it could be a biomarker of overall muscle inflammation.

Keywords: Whole-body MRI; idiopathic inflammatory myopathy; muscle MRI; short-tau inversion recovery image; trunk muscle.