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[Tactile sensor for tissue differentiation in minimally invasive ENT surgery].

BACKGROUND
In endoscopic surgery, stereoscopic vision and tactile information about tissue consistency are no longer available to the surgeon.


METHODS
To compensate for these sensory deficits, various tissues can be characterized with an electromechanical sensor that records their resonance frequencies. In the future, the sensor will be integrated into surgical instruments, providing the surgeon with information about tactile properties of the tissue. We determined the impedance of tissues removed interoperatively (nasal polyps, lymph nodes, cartilage, bone) and different bony structures in a skull specimen. The examinations were carried out with an experimental setup and subsequently with a prototype of the tactile sensor.


RESULTS
Resonance frequency increased with tissue hardness. Measurements with the experimental setup showed resonance frequencies for soft tissues between 15 and 30 Hz. We found that the bony septa of the ethmoid have a resonance frequency of 240-320 Hz and the thicker bony structures at the frontal skull base have a frequency of 780-930 Hz. Measurements of tumors in the upper aerodigestive tract showed that it is possible to differentiate between healthy mucosa, carcinomateous infiltrated mucosa, and carcinomateous undermined mucosa. In case of undermining tumor, the resonance frequency was one third higher than healthy mucosa. These results obtained with the experimental setup were reproduced with the tactile sensor prototype.


CONCLUSIONS
The use of tactile information in endoscopic otolaryngological surgery may improve intraoperative tissue differentiation in the future. The safety of minimal invasive operations in head and neck surgery can be increased.