Estimating patient dielectric losses in NMR images

Thomas William Redpath, James McDonald Strachan Hutchison

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Dielectric losses in the patient may impair radiofrequency receiver coil sensitivity, and transmitter coil efficiency, in nuclear magnetic resonance (NMR) imagers. The frequency dependence of this loss mechanism is derived. Patient losses in a solenoidal head coil used for imaging heads were simulated by a cylindrical saline phantom. The frequency dependence of the loss introduced by the phantom can indicate whether dielectric losses in the patient will be significant compared to eddy current losses. The detuning caused by the phantom is used to calculate an upper limit for the distributed stray capacitance between coil and patient. Given the approximate conductivity of the patient, an upper limit for the dielectric loss can be estimated. Some methods of reducing patient dielectric losses are suggested.

Original languageEnglish
Pages (from-to)295-300
Number of pages6
JournalMagnetic Resonance Imaging
Issue number4
Publication statusPublished - 1984


  • NMR
  • MRI
  • dielectric loss
  • RF coil


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