Regional Variation of Thigh Muscle Composition in Healthy Controls and Patients with Myotonic Dystrophy Type 2, Limb Girdle Muscular Dystrophy Type 2A, and Pompe’s Disease

Introduction Patients with limb girdle muscular dystrophy type 2A (LGMD2A), glycogen storage disease type 2 (Pompe’s disease), and myotonic dystrophy type 2 (DM2) show characteristic involvement of thigh muscles. Chemical shift encoding-based water-fat magnetic resonance imaging (MRI) allows for much warranted quantitative assessment by generating the muscular proton-density fat fraction (PDFF). The aim of this study was to assess regional PDFF variations in the thigh in healthy controls and patients with DM2, LGMD2A, and Pompe’s disease.

Material and Methods A total of 20 healthy subjects (10 female, 30.8 ± 6.1 years of age) and 7 patients were recruited. A spin six-echo three-dimensional (3D) spoiled gradient-echo sequence at 3-T MRI was used for chemical shift-encoding based water-fat separation of the thigh. Three stacks per side (proximal, central, and distal) with 30 slices each were acquired. Muscles were manually segmented to extract PDFF values.

Results Significant unidirectional variation of PDFF with progressive disease was observed for vastus medialis and semimembranosus muscles in DM2, for the quadriceps and gracilis muscles in LGMD2A and for the quadriceps muscles in Pompe’s disease. Proximal to distal PDFF distribution was highly variable within and between diseases. Inter- and intrareader reliability was high, even in severe muscle atrophy.

Conclusion PDFF is a valuable biomarker, allowing quantification of muscle atrophy even in patients with severe progressive disease. We identified target muscles for disease monitoring due to their gradual PDFF increase with progressive disease. High variability between proximal, central, and distal PDFF must be carefully considered in future studies and disease monitoring by MRI.

Die Autoren geben an, dass kein Interessenkonflikt besteht.