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Electromyography in MRI?First recordings of peripheral nerve activation caused by fast magnetic field gradients

2000; Wiley; Volume: 43; Issue: 4 Linguagem: Inglês

10.1002/(sici)1522-2594(200004)43

1522-2594

Alexander Hoffmann, Sonya C. Faber, Konrad J. Werhahn, L. J�ger, Maximilian Reiser,

Advanced MRI Techniques and Applications

Prior studies on the evaluation of stimulation by MRI were based on the subjective feeling of the volunteers. A wide variety of stimulation thresholds between the subjects was observed. In order to exclude subjective perception levels as a cause of this variation, we developed a method to investigate the activation of peripheral nerves after gradient switching by electromyography (EMG) within the MR-imager. Five healthy volunteers were positioned in the MR-scanner with the bridge of the nose at isocenter. The amplitude of sinusoidal pulse trains of the anterior–posterior gradient (rise-times: 200 or 300 μs, various numbers of oscillations) was increased stepwise. Four surface electrodes were placed on the region where a muscle-twitch was reported. Electric activity of the muscle during stimulation experiments was recorded with an MR-compatible electro-physiologic amplifier. Stimulation thresholds were defined by the appearance of an EMG-signal. Thresholds were sharp and consistent with the report of the subjects. Magn Reson Med 43:534–539, 2000. © 2000 Wiley-Liss, Inc.