Isabela Schmitt Untersuchungen zum Einsatz der Laser-induzierten ...

78 7 Summary
7 Summary
Investigations for use of laser induced thermotherapy an canine mammary tumors.
In vitro and in vivo laser induced interstitial thermotherapy (LITT) was carried out as a
minimal invasive alternative to the conventional surgical operative treatment of canine
mamma tumors. A special laser applicator with a circumferential radiation feature was
positioned percutaneously in the center of the tumor using a puncture system. The applicator
was connected to a Nd : YAG laser (1064 nm).
The morphological changes effected using different laser parameters (power density 5 & 7
Watt; radiation time 300, 450, 600, 750 and 900 sec) were investigated in in vitro experiments
using native mammary tumors. The results showed that the size of the coagulation area which
varied between 1.42 x 0.96 cm and 2.96 x 1.96 cm was dependent on the power density and
irradiation time. The histology of the samples revealed morphological changes in the treated
area which was defined as cytolysis.
The seven female patients treated (mean age was 12.4 years) had all been designated as high
risk patients in which conventional surgical therapy was not applicable. A laser power density
of 5 Watts was applied at every puncture point for 450 sec or 600 sec according to the size of
the tumor to be treated. Immediately after treatment a large oedeme developed and an
erythema appeared on the skin surface overlying the tumor whereby the neighbouring normal
tissue showed no reaction to the treatment. Each animal was examined 7, 14 and 60 days post-
operatively. A mean reduction in tumor volume of 58 % was recorded. Serious complications
were not observed.