[In vitro experiments on fluid-modulated microwave ablation].
OBJECTIVE
Evaluation of the enhancing or protecting effects of different fluids during microwave ablation (MWA).


METHODS
3 samples of 17 different fluids (each 20 ml) were heated using MWA at power levels of 10, 20, 30, 40 and 45 watts. Energy was applied until the temperature reached 80 degrees C or the duration of heating exceeded 10 minutes. The cooling-down process was then observed until the temperature reached 30 degrees C.


RESULTS
Gastrografin needed the shortest time to be heated up to 80 degrees C (370 sec), followed by Magnograf (410 sec) and HES 10 % (420 sec). The least heatable fluids were Lipiodol (10 min -54.5 +/- 2.43 degrees C), distilled water (10 min -56 +/- 2.42 degrees C) and Glucose 5 % solution (10 min -56.6 +/- 1.69 degrees C). Fluids which could not be heated well, such as distilled water, Lipiodol or Glucose 5 % solution, had a small slope of the temperature curve as a function of the power level used (m = 0.60 - 0.73), whereas fluids which could be heated well, such as Gastrografin, Magnograf and HES 10 %, had a much steeper slope of the temperature curve as a function of the power level (m = 0.99 - 1.20). With respect to the maximum temperature, the above mentioned groups differed significantly (p < 0.05). The temperature slope correlated strongly with maximum temperatures reached (Pearson correlation coefficient: 0.97).


CONCLUSIONS
By additionally administering a carefully chosen fluid, enhancing or protecting effects during microwave ablation can be observed. Especially Gastrografin, Magnograf and HES 10 % can be used to enhance ablation effects, whereas protective effects can be observed particularly when using Lipiodol, distilled water and Glucose 5 %-solution.
Isfort
P
P
Lehrstuhl für angewandte Medizintechnik, Helmholtz-Institut für Biomedizinische Technik, RWTH Aachen. isfort@hia.rwth-aachen.de
Bruners
P
P
Penzkofer
T
T
Günther
R W
RW
Schmitz-Rode
T
T
Mahnken
A H
AH
D003287:Contrast Media; D003974:Diatrizoate Meglumine; D004564:Electrocoagulation / Q000379:methods*; D019786:Gadolinium DTPA; D005950:Glucose Solution, Hypertonic; D006361:Heating; D006801:Humans; D066298:In Vitro Techniques; D007267:Injections; D007459:Iodized Oil; D008872:Microwaves / Q000627:therapeutic use*; D009369:Neoplasms / Q000601:surgery*; D011300:Preoperative Care; D012996:Solutions; D013696:Temperature; D014867:Water
D003287:Contrast Media; D005950:Glucose Solution, Hypertonic; D012996:Solutions; D014867:Water; D003974:Diatrizoate Meglumine; D007459:Iodized Oil; D019786:Gadolinium DTPA