Abstract Details

Imaging studies such as EIM, QUS, and muscle MRI can reflect on muscle health and correlate well with clinical outcome measures of IBM. However, a direct comparison between these technologies is lacking.

This study explores the relationship between electrical impedance myography (EIM) and quantitative ultrasound (QUS) measures in patients with Sporadic Inclusion Boy Myositis (IBM).

We performed EIM scanning and ultrasound imaging of extremity muscles in patients with IBM. EIM parameters at 50kHz (EIM50) and the ratio of phase values at 50kHz and 211kHz (EIMPR) were recorded. We recorded grayscale levels (GSL) for muscles on ultrasound images, performed Z-score normalization for all parameter values, and compared qualitative assessment of MRI imaging to EIM and GSL.

To date, we have recruited seven patients with IBM. All the subjects were men with an average age of 71.4 +/- 6.0 years. Clinical outcome measures showed an average IBM-FRS score of 26.7 +/- 5.5, 6-minute-walk test of 1030 +/- 186.4 feet, grip strength of 17.0 +/- 8.2 kg, and total manual muscle testing score of 138 +/- 9.6. Preliminary analysis revealed a strong correlation between the EIMPR and GSL values from the averaged lower extremity muscle groups (r = 0.812, p = 0.027). We noted a moderate correlation between the EIM and QUS parameters in the medial gastrocnemius. Only four patients had muscle MRI, and we noticed a trend between EIM50 phase value and fatty infiltration of muscles tissues on muscle MRI.

EIM and QUS parameters in IBM are related, and large-scale studies are warranted to validate the relationship between these technologies. These relatively cost-effective technologies may potentially serve as a surrogate for muscle MRI and monitor IBM progression in the clinic setting.