Measurement of ventilation- and perfusion-mediated cooling during laser ablation in ex vivo human lung tumors.
OBJECTIVE
Perfusion-mediated tissue cooling has often been described in the literature for thermal ablation therapies of liver tumors. The objective of this study was to investigate the cooling effects of both perfusion and ventilation during laser ablation of lung malignancies.


METHODS
An ex vivo lung model was used to maintain near physiological conditions for the specimens. Fourteen human lung lobes containing only primary lung tumors (non-small cell lung cancer) were used. Laser ablation was carried out using a Nd:YAG laser with a wavelength of 1064 nm and laser fibers with 30 mm diffusing tips. Continuous invasive temperature measurement in 10 mm distance from the laser fiber was performed. Laser power was increased at 2 W increments starting at 10 W up to a maximum power of 12-20 W until a temperature plateau around 60 °C was reached at one sensor. Ventilation and perfusion were discontinued for 6 min each to assess their effects on temperature development.


RESULTS
The experiments lead to 25 usable temperature profiles. A significant temperature increase was observed for both discontinued ventilation and perfusion. In 6 min without perfusion, the temperature rose about 5.5 °C (mean value, P<0.05); without ventilation it increased about 7.0 °C (mean value, P<0.05).


CONCLUSIONS
Ventilation- and perfusion-mediated tissue cooling are significant influencing factors on temperature development during thermal ablation. They should be taken into account during the planning and preparation of minimally invasive lung tumor treatment in order to achieve complete ablation.
Vietze
Andrea
A
Department of Diagnostic Radiology and Neuroradiology, Ernst-Moritz-Arndt-Universitaet Greifswald, Sauerbruchstraße, 17487 Greifswald, Germany. anvie@gmx.de
Koch
Franziska
F
Laskowski
Ulrich
U
Linder
Albert
A
Hosten
Norbert
N
D006355:Heart-Lung Machine; D006801:Humans; D006979:Hyperthermia, Induced; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000379:methods*; D008175:Lung Neoplasms / Q000628:therapy*; D009336:Necrosis; D010477:Perfusion; D018709:Statistics, Nonparametric; D013696:Temperature