Physiologic effects of intense MR imaging gradient fields

The strength duration relationship for peripheral nerve stimulation by MR imaging pulsed gradient magnetic fields was measured in 84 human subjects. The data were fitted to the hyperbolic strength-duration relationship: dB/dt=b(1 + c/d), where b is rheobase, c is chronaxie, and d is duration, and dB...

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Bibliographic Details
Published inNeuroimaging clinics of North America Vol. 9; no. 2; p. 363
Main Authors Bourland, J D, Nyenhuis, J A, Schaefer, D J
Format Journal Article
LanguageEnglish
Published United States 01.05.1999
Subjects
Abdominal Muscles - physiology
Adult
Animals
Dogs
Electric Stimulation
Electrocardiography
Female
Humans
Magnetic Resonance Imaging - adverse effects
Magnetic Resonance Imaging - instrumentation
Magnetic Resonance Imaging - methods
Magnetics - adverse effects
Male
Muscle Contraction - physiology
Muscle, Skeletal - innervation
Pain - etiology
Pain Threshold - physiology
Respiration
Sensation - physiology
Sensory Thresholds - physiology
Thorax - physiology
Vagus Nerve - physiology
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Summary:The strength duration relationship for peripheral nerve stimulation by MR imaging pulsed gradient magnetic fields was measured in 84 human subjects. The data were fitted to the hyperbolic strength-duration relationship: dB/dt=b(1 + c/d), where b is rheobase, c is chronaxie, and d is duration, and dB/dt is reported as the maximal value on the axis of the bore. For sensation threshold, average (b,c) (15 T/s, 0.37 ms) for the y-gradient and (26 T/s, 0.38 ms) for the z-gradient coil. The dB/dt intensity to induce a sensation which the subject described as uncomfortable was about 50% above the sensation threshold. Experiments with dogs showed that the cardiac stimulation by pulsed magnetic gradient fields is exceedingly unlikely.
ISSN:1052-5149