Baseline fat fraction is a strong predictor of disease progression in Becker muscular dystrophy

Figures

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  FIGURE 1. Representative fat fraction (upper row), water T2 maps (middle row) and MRS spectra of the soleus (lower row) for a patient in a relatively early (left column) and relatively late (right column) stage of the disease. For the water T2 maps, voxels that fitted on the boundaries of the dictionary (i.e., 0 and 60 ms) were excluded, labelled as 0 in these maps. The MRS spectra were fitted in the time domain using Gaussian line shapes and prior knowledge of the linewidths of the PDE and ß‐ATP. 27 FF, fat fraction; PCr, phosphocreatine; PDE, phosphodiester; Pi, inorganic phosphate; ppm, parts per million

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  FIGURE 2. A schematic representation of the workflow of the statistical analysis. The upper two rows indicate the type of data available for the upper and lower leg: fat fraction (FF), standard deviation of water T2 (stdT2) and phosphodiester over ATP (PDE/ATP). The third row refers to the two models and the lines indicate in which models the data were included

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  FIGURE 3. Prediction fit (blue line) and 95% confidence interval (light blue band) for the effect of baseline fat fraction (FFbase) on fat fraction increase at 2‐year follow‐up (∆FF), including a fourth‐order polynomial association. The 340 available datapoints are indicated by the dots. In this analysis, both upper and lower leg data were used

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  FIGURE 4. Prediction fits (blue lines) for the three fixed effects, (A) Baseline fat fraction (FFbase), (B) Standard deviation of water T2 (stdT2) and (C) Phosphodiester over ATP (PDE/ATP), and their effect on fat fraction at 2‐year follow‐up (∆FF), while keeping the other two variables constant at the median value, with the 95% confidence intervals (light blue bands) and the partial residuals for the 86 available datapoints (dots). In this analysis, only lower leg data were used