Multiparametric Muscle Ultrasound Imaging for Assessment of Muscle Inflammation in Idiopathic Inflammatory Myopathies

Myositis is a rare systemic autoimmune disease with limited treatment options. Chronic muscle inflammation frequently leads to increased fat, atrophy, and scarring in muscles over time causing functional disability in 1 in 4 patients with myositis. Cost effective and objective tools that can capture early, potentially reversible muscle inflammation is currently lacking in myositis.

As a widely available, efficient, and inexpensive tool, muscle ultrasound has not been studied adequately in myositis. This study centers on laying the groundwork in understanding the potential of muscle ultrasound in assessment of muscle disease in patients with myositis.

The participants who complete all study-related tests will be provided with a gift card.

Inclusion Criteria for Patients:

Adults (≥18 years old) seen at the Rush University Medical Center Outpatient Rheumatology Clinic, who a) fulfill the probable/definite diagnosis of IIM according to the EULAR-ACR Myositis Classification Criteria, b) provide consent to undergo both muscle US and MRI at Rush within 3 days of each other, and c) have no contraindications for MRI, will be eligible for enrollment. Patients with varying levels of clinical disease activity will be enrolled to ensure that the US findings represent a wide spectrum of changes. Thus, recruitment will include both newly diagnosed cases (defined as those within 6 months of diagnosis) as well as those with long-standing disease.

Exclusion Criteria for Patients:

The patients who do not fulfill the probable/definite diagnosis of IIM according to the EULARACR Myositis Classification Criteria, those who will not be able to undergo muscle US and MRI at Rush within 3 days of each other; or those who have contraindications to undergo MRI will be excluded. Contraindications for MRI are listed here as having one of the following:

• Cardiac pacemaker
• Implanted cardiac defibrillator
• Internal pacing wires
• Clips such as cerebral, carotid, or aortic aneurysm
• Cochlear implants
• Any implant held in by magnet
• Swan-Ganz catheter
• Pregnancy

Inclusion Criteria for Healthy Controls:

Healthy controls (≥18 years old) with no known history of neuromuscular disorder who provide consent to undergo both muscle US and MRI at Rush within 3 days of each other and have no contraindications for MRI will be eligible for enrollment.

Exclusion Criteria for Healthy Controls:

The individuals who have history of a neuromuscular disorder; those who will not be able to undergo muscle US and MRI at Rush within 3 days of each other; and those who have contraindications for MRI (as listed above) will be excluded from the study.