Towards in vivo differentiation of brain tumor versus normal tissue by means of torsional resonators

It was tested to what extend torsional acoustic resonators can serve to in vivo differentiate between healthy and tumorous brain tissue. The resonators employed consist of crystalline quartz. They are cylindrically shaped. The resonance frequency at the fundamental is 78 kHz. The best correlation between the shifts of resonance frequency and resonance bandwidth, on the one hand, and the state of the tissue, on the other, was found when analyzing ratios of the shifts in resonance frequency and resonance bandwidth. These ratios are independent of contact area. Taking data on the fundamental mode as well as the third overtone further improved the efficiency and precision of the technique. These results suggest that torsional resonators can serve as diagnostic tools in neurosurgery.

► Torsional acoustic resonators have been used on living animals to distinguish between tumorous and healthy tissue.
► If the specimens are accessible well, one finds that the tumorous tissue is stiffer than the healthy tissue.
► Taking ratios between shifts of frequency and bandwidth improves the correlation between tissue state and sensor output.