Quantitative muscle ultrasound in neuromuscular disorders using the parameters 'intensity', 'entropy', and 'fractal dimension'.

Background and purpose:  Ultrasound is a useful non-invasive instrument in visualizing physiological and pathological morphology in skeletal muscle. Here, we evaluate the possibility that quantitative muscle ultrasound using the parameters ‘intensity’, ‘entropy’, and ‘fractal dimension’ is a feasible method to distinguish between dystrophic myopathies (DM), inflammatory myopathies (IM), and motor neuron disorders. Methods:  Seven patients with IM, 12 patients with DM, nine patients with motor neuron diseases, and 24 healthy subjects underwent an identical ultrasound examination protocol, applied on gastrocnemius and tibialis anterior muscle. Analysis parameters were applied on grey scale images as well as on gradient images. Results:  Statistical evaluation revealed no significant differences in the evaluated parameters for differentiation of the distinct disease groups. Compared with healthy controls however we found statistically significant differences between almost of all the investigated parameters, even in disease cases with clinically unaffected distal musculature. Conclusion:  The parameters are able to distinguish between healthy and affected musculature but not between distinct disease entities. Studies are needed to establish whether or not the parameters are helpful to monitor muscle involvement and disease progression in neuromuscular diseases.