Characterization of involuntary spontaneous focal muscle activity by means of motion-sensitive magnetic resonance imaging and automated post-processing of data

• Applicants: Professor Dr. Fritz Schick; Professor Dr. Ludger Schöls; Professor Dr.-Ing. Bin Yang
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 337721085

In single images of series of diffusion-sensitive single-shot magnetic resonance images of resting skeletal muscles, distinct regionally limited signal voids often occur even in healthy subjects. These signal voids show different geometry and localization in the course of a series of measurements, with some muscle groups being affected more frequently than others. The signal voids show a high correlation to weak electrical activities in the simultaneously derived surface electromyography (sEMG). Short involuntary focal contractions, which microscopically do not affect all muscle fibers equally and thus lead to incoherent movement patterns, are assumed to be the cause of the signal voids. The relative movements on the microscopic scale induce a dephasing of the signal components of the pixels (like real diffusion movements) and lead to the observed signal voids in diffusion-sensitive images. The pattern of signal voids indicates spontaneous activities with individual activations of motor neurons. This research project aims to further characterize the phenomenon of spontaneous muscle activity, based on the findings of the funded initial DFG proposal, in different age and gender groups of healthy volunteers and in specific patient groups. A parallel application of surface electromyographic (sEMG) methods and sEMG triggering of the acquisition of MRI images will be used to characterize more precisely the course of the mechanical reaction, which is delayed compared to the electrical activity. Furthermore, the value of the new method will be investigated by comparing it with clinically established diagnostic procedures. In neurological diagnostics for the investigation of spontaneous muscular movements (fasciculations), sonographic methods, which are sometimes difficult to detect deeper muscle layers, as well as electromyographic examinations with needle electrodes are available. Although the latter method is somewhat invasive, it can reveal specific changes in motor neuron diseases. In the first phase of the project, MRI sequences and evaluation procedures will be adapted and optimized for applications in muscle areas that are relevant for neuromuscular diseases. A further development of the combined sEMG-MRI investigation with regard to the robustness of the detection algorithms for prospective images will provide a detailed insight into the interrelationships of electrical and mechanical activities. In the second phase of the project, systematic investigations with different clinically established methods (muscle sonography and needle electromyography) will be performed on healthy volunteers and specific patient groups. This will allow a better classification of the results of the MRI method by evaluation of its strengths and weaknesses compared to established procedures.

• DFG Programme: Research Grants