Email: egersin@gwdg.de
CompanyName: University Hospital Goettingen
Country: Germany
Abstract: Cancer tissue monitoring during photodynamic treatment using bioimpedance spectroscopy
In earlier experiments we investigated
the changes in tumor tissue during hyperthermia by impedance spectroscopy. The
aim of the present investigation is the detection of the effects of photodynamic
treatment (PDT) on tumor tissue without and with additional application of hyperthermia.
After administration of the photo-active drug, the tumors (DS sarcoma) grown
on the hind feet of rats were irradiated with suitably filtered light of a halogen
lamp during 60 min. Before, during and after the irradiation, the impedance
was measured in the frequency range of 100 Hz to 3.7 MHz using a pair of titanium
needle electrodes (with fractal surfaces) inserted into the tumor. Additionally,
the temperatures of the tumor and the body as well as the mean arterial blood
pressure were recorded.
In contrast to an exclusive hyperthermic treatment (producing an extracellular
edema), the evaluation of the impedance spectra shows that the PDT causes an
intracellular edema, beginning with the onset of the irradiation. The effect
is increased by additional application of hyperthermia.
The method of impedance spectroscopy (and presumably multifrequency tomography
as well) proves to be a helpful tool for immediate detection of the alterations
in tissue during treatment.