Table 1 Summary of the well-established rating scales on MRI concerning the visual rating of dystrophic change of striated muscle tissue
Grade Mercuri et al. 2002 [25] Kornblum et al. 2006 [27] Fischer et a. 2008 [26]
0 Normal appearance Normal appearance
1 Normal appearance Discrete moth-eaten appearance with sporadic T1 hyperintense areas Mild: traces of increased signal intensity on the T1-weighted MR sequences
2 Mild involvement: Early moth-eaten appearance with scattered small areas of increased signal or with numerous discrete areas of increased signal with beginning confluence, comprising less than 30% of the volume of the individual muscle a. Moderate moth-eaten appearance with numerous scattered T1 hyperintense areas Moderate: increased T1-weighted signal intensity with beginning confluence in less than 50% of the muscle
b. Late moth-eaten appearance with numerous confluent T1 hyper-intense areas
3 Moderate involvement: Late moth-eaten appearance with numerous discrete areas of increased signal with beginning confluence, comprising 30-60% of the volume of the individual muscle Complete fatty degeneration, replacement of muscle by connective tissue and fat Severe: increased T1-weighted signal intensity with beginning confluence in more than 50% of the muscle
4 Severe involvement: Washed-out appearance, fuzzy appearance due to confluent areas of increased signal or an end-stage appearance, with muscle replaced by increased density connective tissue and fat, and only a rim of fascia and neurovascular structures distinguishable End-stage appearance, entire muscle replaced by increased density of connective tissue and fat