Volumetric Muscle Composition Analysis of Sporadic Inclusion Body Myositis Patients using Fat-Water Separated MRI: A Repeatability Study

Topic:

Translational Research

Poster Number: 165

Author(s):

John Heerfordt, PhD, AMRA Medical, Markus Karlsson, PhD, AMRA Medical, Midori Kusama, Department of Radiology, National Center of Neurology and Psychiatry, Tokyo, Japan, Seiya Ogata, DVD PhD, Drug Metabolism & Pharmacokinetics Research Laboratories, Daiichi Sankyo, Co. Ltd., Tokyo, Japan, Ryuta Mukasa, PhD, Translational Science Department II, Daiichi Sankyo, Co. Ltd., Tokyo, Japan, Naoki Kiyosawa, PhD, Translational Science Department II, Daiichi Sankyo, Co. Ltd., Tokyo, Japan, Noriko Sato, MD, PhD, National Center of Neurology and Psychiatry, Tokyo, Japan, Thobias Romu, PhD, AMRA Medical AB, Linköping, Sweden, Per Widholm, MD, AMRA Medical AB, Linköping, Sweden, Olof Dahlqvist Leinhard, PhD, AMRA Medical AB, Linköping, Sweden, André Ahlgren, PhD, AMRA Medical AB, Linköping, Sweden, Madoka Mori-Yoshimura, MD, PhD, National Center of Neurology and Psychiatry, Tokyo, Japan

Background
Many neuromuscular disorders involve loss and fat replacement of skeletal muscle. Volumetric MRI-based analysis of muscle volume and muscle fat has emerged as a promising technique for monitoring disease progression and evaluating treatment response. However, the experience of using the approach in sporadic inclusion body myositis (sIBM) remains limited.

Objectives
This work aimed at evaluating the within-scanner repeatability of MRI-based muscle composition analysis in such a patient population. N = 10 sIBM patients underwent two MRI examinations in a test-retest setup on a 3T Siemens Verio. A T1-weighted Dixon acquisition with coverage of the full legs was employed. Subsequently, the following anatomical regions were segmented: quadriceps, hamstrings, adductors, gastrocnemius medialis and tibialis anterior. The segmentations were used for measuring the lean muscle volume (LMV), the muscle fat fraction (MFF), and the muscle fat infiltration (MFI, defined as the MFF of the contractile muscle tissue) of each region bilaterally. Lastly, the cohort average as well as the within-subject standard deviation (sw) and the within-subject coefficient of variation (CVw) were computed for each region and measurement type.

Results
The average LMV of the different regions within the cohort ranged from 6.9 cl (tibialis anterior) to 72.0 cl (quadriceps), the average MFF from 21.7% (adductors) to 43.5% (gastrocnemius medialis), and the average MFI from 13.0% (adductors) to 22.5% (gastrocnemius medialis). The measurements showed a high repeatability although the precision varied among regions; sw ranged from 0.27 – 1.80 cl for LMV, from 0.68 – 1.32 percentage points for MFF, and from 0.19 – 0.71 percentage points for MFI. Similarly, CVw varied between 1.48% – 9.34% for LMV, 2.95% – 7.14% for MFF, and 0.91% – 4.53% for MFI.

Conclusions
Volumetric MRI-based muscle composition analysis of sIBM patients proved to be highly repeatable, which is a prerequisite for usage in natural history studies as well as clinical trials.