By Topic

Gelled versus nongelled phantom material for measurement of MRI-induced temperature increases with bioimplants

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

13 Author(s)
Park, S.M. ; Sch. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA ; Nyenhuis, J.A. ; Smith, C.D. ; Lim, E.J.
more authors

Measurements in phantoms are used to predict temperature changes that would occur in vivo for medical implants due to the radio frequency (RF) field in magnetic resonance imaging (MRI). In this study, the impact of concentration of the gelling agent in a saline-based phantom on the RF-induced temperature rise was measured using an apparatus that accurately reproduces the RF environment present in a 1.5-T whole-body MR system. The temperature was measured using fluoroptic thermometry at the electrode and other sites for a deep brain neurostimulation system. The average power deposition in the 30-kg phantom was about 1.5 W/kg. Four phantom formulations were evaluated, using different concentrations of polyacrylic acid (PAA) added to saline solution, with NaCl concentration adjusted to maintain an electrical conductivity near 0.24 S/m. The greatest temperature rises occurred at the electrode, ranging from 16.2°C for greatest concentration of PAA to 2.9°C for only saline solution. The temperature rise attained the maximal value for sufficient concentration of PAA. Similar behavior was observed in the temperature versus time relationship near a current-carrying resistor, immersed in gel and saline, which was used to model a localized heat source. The temperature rise for insufficient PAA concentration is reduced due to convection of phantom material. In conclusion, an appropriate gelling agent is required to accurately simulate the thermal properties of body tissues for measurements of RF-induced heating with medical implants.

Published in:

Magnetics, IEEE Transactions on  (Volume:39 ,  Issue: 5 )