Human intramuscular temperature and heat flow transients at
rest.
Binzoni, Tiziano, Emile Hiltbrand, Bengt Kayser, Guido Ferretti, and
Francois Terrier.
Dept. of Radiology, HCUG, University of Geneva, Switzerland, Dept.
of Physiology, CMU, University of Geneva, Switzerland
APStracts 2:0258A, 1995.
A general model for heat exchange, comprising the major models in the
litterature, was developed. Temperature changes as a function of
space and time were determined on six rest ing humans (age 32.7 +/-
4.5 years) during temperature transients by magnetic resonance
imaging (MRI), so that the exact solution of the model was obtained.
These results allowed application of the model, e.g. to the analysis
of transient muscle heat flow changes, which could never be assessed
by previous steady-state analyses. A microthermocouple was inserted
in muscle vastus lateralis 2-to-3 cm below the skin surface. The
measured temperature was used for calibrating the pixel intensity of
a temporal series of transaxial MR images, obtained with a spin echo
sequence around the microthermocouple position. After muscle
temperature was increased by immersion in a controlled water bath,
MRI acquisition was performed while muscle temperature was
decreasing. Temperature maps relative to space and time inside a
homogeneous region of interest were reconstructed by neural networks,
showing specific tem perature patterns. Subsequently calculated heat
flows (with negative sign) appeared to increase linearly as
temperature decreased, until a maximum was attained at a critical
temperature, below which dramatic consistent heat flow changes were
found. In conclusion MRI is indeed a powerful technique, useful to
study the determinants of muscle temperature and heat flows changes
in space and time.
Received 22 February 1995; accepted in final form 8 June 1995.
APS Manuscript Number A203-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.