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Monitoring Temperature‐Induced Changes in Tissue during Hyperthermia by Impedance Methods a
Author(s) -
GERSING EBERHARD
Publication year - 1999
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1999.tb09444.x
Subject(s) - tissue fluid , hyperthermia , extracellular fluid , dielectric spectroscopy , chemistry , electrical impedance , volume (thermodynamics) , conductivity , thermal conduction , materials science , skeletal muscle , electrolyte , admittance , biomedical engineering , extracellular , anatomy , thermodynamics , composite material , medicine , physics , electrode , biochemistry , quantum mechanics , electrochemistry
A bstract : The electrical conduction in living tissue depends on temperature in two ways: (1) the temperature coefficients of conductivity of the intra‐ and extracellular electrolytes and (2) temperature‐induced fluid volume shifts in the tissue. Measurements in rat skeletal muscle and tumors (DS sarcoma) during hyperthermic treatment reveal that the contribution of fluid volume shifts to changes in conduct‐ance is of the same order of magnitude as the change in fluid conductivity. In skeletal muscles, blood volume changes are caused by the temperature‐dependent regulation of the vessel diameter (vasodilatation). In tumors, fluid content changes irregularly. These effects render temperature measurements by impedance methods, for example, electrical impedance tomography (EIT), questionable. However, monitoring fluid volume changes in tissue and the state of cell membranes is an interesting application of impedance (or admittance) spectroscopy and tomography as well.