Affiliations: [a] Department of Neurology, Heimer Institute for Muscle Research, BG-University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| [b] Department of Radiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| [c] Department of Neurology, University Hospital St. Josef, Ruhr-University Bochum, Bochum, Germany
Correspondence:
[*]
Correspondence to: Robert Rehmann, Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany. Tel.: 0234 / 302 6810; E-mail: Robert.Rehmann@rub.de.
Abstract: Background:Myotonic Dystrophies type 1 and type 2 are hereditary myopathies with dystrophic muscle degeneration in varying degrees. Differences in muscle diffusion between both diseases have not been evaluated yet. Objective:To evaluate the ability of muscle diffusion tensor imaging (mDTI) and Dixon fat-quantification to distinguish between Myotonic Dystrophy (DM) type 1 and type 2 and if both diseases show distinct muscle involvement patterns. Methods:We evaluated 6 thigh and 7 calf muscles (both legs) of 10 DM 1, 13 DM 2 and 28 healthy controls (HC) with diffusion tensor imaging, T1w and mDixonquant sequences in a 3T MRI scanner. The quantitative mDTI-values axial diffusivity (λ1), mean diffusivity (MD), radial diffusivity (RD) and fractional anisotropy (FA) as well as fat-fraction were analysed. CTG-triplet repeat-length of DM 1 patients was correlated with diffusion metrics and fat-fraction. Results:mDTI showed significant differences between DM 1 and DM 2 vs. healthy controls in diffusion parameters of the thigh (all p < 0.001) except for FA (p = 0.0521 / 0.8337). In calf muscles mDTI showed significant differences between DM 1 and DM 2 patients (all p < 0.0001) as well as between DM 1 patients and controls (all p = 0.0001). Thigh muscles had a significant higher fat-fraction in both groups vs. controls (p < 0.05). There was no correlation of CTG triplet length with mDTI values and fat-fraction. Discussion:mDTI reveals specific changes of the diffusion parameters and fat-fraction in muscles of DM 1 and DM 2 patients. Thus, the quantitative MRI methods presented in this study provide a powerful tool in differential diagnosis and follow-up of DM 1 and DM 2, however, the data must be validated in larger studies.
Keywords: Myotonic Dystrophy type 1, Myotonic Dystrophy type 2, diffusion tensor imaging, muscle, skeletal, magnetic resonance imaging
