Magnetic resonance imaging of leg muscles in patients with myotonic dystrophies

Abstract

Magnetic resonance imaging (MRI) of muscles has recently become a significant diagnostic procedure in neuromuscular disorders. There is a lack of muscle MRI studies in patients with myotonic dystrophy type 1 (DM1), especially type 2 (DM2). To analyze fatty infiltration of leg muscles, using 3.0 T MRI in patients with genetically confirmed DM1 and DM2 with different disease durations. The study comprised 21 DM1 and 10 DM2 adult patients. Muscle MRI was performed in axial plane of the lower limbs using T1-weighted (T1w) sequence. Six-point scale by Mercuri et al. was used. Fatty infiltration registered in at least one muscle of lower extremities was found in 71% of DM1 and 40% of DM2 patients. In DM1 patients, early involvement of the medial head of gastrocnemius and tibialis anterior muscles was observed with later involvement of other lower leg muscles and of anterior and posterior thigh compartments with relative sparing of the rectus femoris. In DM2, majority of patients had normal MRI findings. Early involvement of lower legs and posterior thighs was found in some patients. Less severe involvement of the medial head of the gastrocnemius compared to other lower leg muscles was also observed, while involvement of proximal muscles was rather diffuse than selective. It seems that both in DM1 and DM2 some muscles may be affected before weakness is clinically noted and vice versa. We described characteristic pattern and way of progression of muscle involvement in DM1 and DM2.

Lower extremity muscle pathology in myotonic dystrophy type 1 assessed by quantitative MRI

“…9 The typical fat infiltration pattern recorded by our quantitative MRI investigation largely agrees with the semiquantitative Lamminen score in this and other qualitative MRI studies. 9,26–29 However, in the objective assessment of disease severity and progression and the evaluation of clinical trials, quantitative analysis of MRIs covering entire muscles—as presented in this study—is essential. To date, only 1 quantitative MRI study, limited to the tibialis anterior, has been performed in DM1.…”

T2-Weighted Dixon Turbo Spin Echo for Accelerated Simultaneous Grading of Whole-Body Skeletal Muscle Fat Infiltration and Edema in Patients With Neuromuscular Diseases

“…6,11,12 In this clinical setting, the two ratings are mostly used in consensus by two readers. 13,14 To the best of the author's knowledge, a quantitative evaluation of the interrater accuracy of the ratings scales for edematous changes was performed in the present work for the first time. The observed interrater agreement of the T 2 -weighted images assessing edematous changes was lower compared with the ratings of fatty infiltration.…”

Myopathies with finger flexor weakness: Not only inclusion‐body myositis

“…A characteristic pattern of muscle involvement has been reported in DM1, 103,104,108 but the clinical phenotype is often readily recognized, reducing the diagnostic value of MRI. Meanwhile, many DM2 patients have a normal muscle MRI, and a number of different patterns of muscle involvement have been described in other DM2 patients 108–111 …”