title: Safe MRI-Compatible electrical muscle stimulation (EMS) system.
abstract: To develop an inexpensive magnetic resonance imaging (MRI)-compatible electrical muscle stimulation (EMS) unit and test it for safety and efficacy.
  
  
  
  A simple MRI-compatible EMS device was developed using radiofrequency (RF) translucent electrodes at 3T. RF heating concerns were assessed using optical temperature measurements at electrode sites, during scanning of a phantom. EMS efficacy and consistency was investigated through in vivo (n = 5) measures of31P-MRS phosphocreatine (PCr) reduction, and altered blood oxygen level-dependent (BOLD) signal and the results were compared to effects from equivalent voluntary effort on the same subjects.
  
  
  
  The presence of an EMS pulse did not interfere with the T2* signal in a phantom. However, signal-to-noise ratio (SNR) was reduced by 70% at electrode sites, but only by 10% 4 cm distally. Under RF intense conditions, the temperature at the electrode site increased by only 4.7°C over a 16-minute time span. In vivo muscle stimulation resulted in 13.5 ± 1.8% reduction in PCr, which was not significantly (P < 0.195) different from voluntary contraction. Reproducible muscle BOLD signal changes following EMS were noted, with a maximal increase of 10.0 ± 2.6% seen in the central soleus. For soleus and gastrocnemius compartments, EMS produced significantly higher BOLD signal change compared to voluntary contraction (P < 0.05).
  
  
  
  A safe and inexpensive MRI-compatible EMS unit can be easily built for evaluating muscle function and metabolism within a 3T MRI scanner. Clinical applications might include evaluating skeletal muscle function in patients with limited or absent voluntary skeletal motor function or inadequate exercise capacity. J. Magn. Reson. Imaging 2016;44:1530-1538.
authors.affiliation: School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada.
authors.forename: Alireza
authors.initials: A
authors.lastname: Akbari
authors.affiliation: School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada.
authors.forename: Conrad P
authors.initials: CP
authors.lastname: Rockel
authors.affiliation: School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.|Toronto Rehabilitation Institute, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Dinesh A
authors.initials: DA
authors.lastname: Kumbhare
authors.affiliation: School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada.|Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Noseworthy
mesh_terms: D000328:Adult; D016477:Artifacts; D004599:Electric Stimulation Therapy / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004869:Equipment Safety; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D057054:Molecular Imaging / Q000295:instrumentation*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010725:Phosphocreatine; D010100:Oxygen
keywords: 31P-MRS; MRI; blood oxygen level dependent (BOLD); electrical muscle stimulation (EMS); skeletal muscle