Development of a synchronized system for continuous acquisition and analysis of ultrasound joint angle, and EMG

Ultrasound and electromyography (EMG) are two of the most often used diagnostic tools for muscles. However, there is lack of a system for continuously capturing both signals with a synchronized procedure. This study presents a new system for this purpose. The system comprises an ultrasound scanner, a pulser/receiver, an EMG amplifier, and a PC with A/D converter cards for data acquisition and analysis. The A-mode and B-mode ultrasound data, which were digitized by the A/D converter and a video capture card respectively, could be simultaneously captured by the PC together with the surface EMG (SEMG) signal, which was digitized by another data acquisition card. Time markers for all frames of ultrasound and SEMG signals were recorded to synchronize the two data streams. The tissue deformation was extracted inform the ultrasound signals or images using cross-correlation algorithms. The RMS and spectrum of SEMG was calculated to study the muscle activity. In addition, the joint angle signal was also be synchronized with ultrasound and SEMG signals. The experiments involving 5 subjects were carried out to test the performance of the system. Preliminary results showed that the muscle deformations extracted from the ultrasound data were well correlated with the changes of SEMG RMS. The system may have potential values in the investigation of muscle properties and activities.