Sporadic Inclusion Body Myositis: MRI Findings and Correlation With Clinical and Functional Parameters

• Published in: American journal of roentgenology (1976) Vol. 209; no. 6; pp. 1340 - 1347
• Main Authors: Guimaraes, Julio Brandao, Zanoteli, Edmar, Link, Thomas M., de Camargo, Leonardo V., Facchetti, Luca, Nardo, Lorenzo, Fernandes, Artur da Rocha Correa
• Format: Journal Article
• Language: English
• Published: United States 01.12.2017
• Subjects: Aged; Biopsy; Disability Evaluation; Extremities; Female; Humans; Magnetic Resonance Imaging - methods; Male; Middle Aged; Myositis, Inclusion Body - diagnostic imaging; Myositis, Inclusion Body - physiopathology; Prospective Studies; idiopathic myopathy; atrophy; sporadic body inclusion myositis; inflammatory myopathies; MRI; fat infiltration
• ISSN: 0361-803X; 1546-3141; 1546-3141
• DOI: 10.2214/AJR.17.17849

The purpose of this prospective study is to assess MRI findings in patients with sporadic inclusion body myositis (IBM) and correlate them with clinical and functional parameters. This study included 12 patients with biopsy-proven sporadic IBM. All patients underwent MRI of the bilateral upper and lower extremities. The images were scored for muscle atrophy, fatty infiltration, and edema pattern. Clinical data included onset and duration of disease. Muscle strength was measured using the Medical Research Council (MRC) scale, and functional status was assessed using the Modified Rankin Scale. Correlation between MRI and different clinical and functional parameters was calculated using the Spearman rank test and Pearson correlation. All patients showed MRI abnormalities, which were more severe within the lower limbs and the distal segments. The most prevalent MRI finding was fat infiltration. There was a statistically significant correlation between disease duration and number of muscles infiltrated by fat (r = 0.65; p = 0.04). The number of muscles with fat infiltration correlated with the sum of the scores of MRC (r = -0.60; p = 0.04) and with the Modified Rankin Scale (r = 0.48; p = 0.03). Our findings suggest that most patients with biopsy-proven sporadic IBM present with a typical pattern of muscle involvement at MRI, more extensively in the lower extremities. Moreover, MRI findings strongly correlated with clinical and functional parameters, because both the extent and severity of muscle involvement assessed by MRI and clinical and functional parameters are associated with the early onset of the disease and its duration.