A resistive heating system for homeothermic maintenance in small animals

Purpose To develop an MR-compatible resistive heater for temperature maintenance of anaesthetized animals. Materials and Methods An MR-compatible resistive electrical heater was formed from a tightly-wound twisted pair wire, interfaced to a homeothermic maintenance controller. Fat-suppressed images and localized spectra were acquired with the twisted pair heater and a near-identical single strand heater during operation at maximum power. Data were also acquired in the absence of heating to demonstrate the insensitivity of MR to distortions arising from the passage of current through the heater elements. The efficacy of temperature maintenance was examined by measuring rectal temperature immediately following induction of general anesthesia and throughout and after the acquisition of a heater artifact-prone image series. Results Images and spectra acquired in the presence and absence of DC current through the twisted pair heater were identical whereas the passage of current through the single strand wire created field shifts and lineshape distortions. Temperature that is lost during anesthesia induction was recovered within approximately 10–20 minutes of induction, and a stable temperature is reached as the animal's temperature approaches the set target. Conclusion The twisted pair wire heater does not interfere with MR image quality and maintains adequate thermal input to the animal to maintain body temperature.

[1]  Christopher J. Gordon,et al.  Temperature Regulation in Laboratory Rodents , 1993 .

[2]  Douglas K. Taylor.  Study of two devices used to maintain normothermia in rats and mice during general anesthesia. , 2007, Journal of the American Association for Laboratory Animal Science : JAALAS.

[3]  D. Sessler,et al.  Mild preseptic hypothermia is detrimental in rats* , 2004, Critical care medicine.

[4]  T. K. Hunt,et al.  Mild hypothermia during isoflurane anesthesia decreases resistance to E. coli dermal infection in guinea pigs , 1994, Acta anaesthesiologica Scandinavica.

[5]  K. Otto,et al.  Anaesthesia, Analgesia and Euthanasia , 2012 .

[6]  Patrick McConville,et al.  Small animal preparation and handling in MRI. , 2011, Methods in molecular biology.

[7]  A simple and inexpensive system for controlling body temperature in small animal experiments using MRI and the effect of body temperature on the hepatic kinetics of Gd-EOB-DTPA. , 2013, Magnetic resonance imaging.

[8]  Adam C Caro,et al.  Comparison of thermoregulatory devices used during anesthesia of C57BL/6 mice and correlations between body temperature and physiologic parameters. , 2013, Journal of the American Association for Laboratory Animal Science : JAALAS.

[9]  P. Flecknell,et al.  Laboratory animal anaesthesia , 1996 .

[10]  V. Hampshire,et al.  Red-carpet rodent care: making the most of dollars and sense in the animal facility. , 2000, Lab animal.

[11]  K. Otto.  CHAPTER 34 – Anesthesia, Analgesia and Euthanasia , 2004 .

[12]  F. Campos,et al.  Glutamate Excitoxicity Is the Key Molecular Mechanism Which Is Influenced by Body Temperature during the Acute Phase of Brain Stroke , 2012, PloS one.