Cavitation activity induced by spring-loaded core needle biopsy devices.

Core needle biopsy is a common medical procedure to obtain tissue samples with tissue architecture for pathological assessment. One prevalent method involves the use of spring-loaded core needle biopsy devices, or "biopsy guns". Despite their intense motion dynamics when shot through tissue, possible cavitation activity has received limited attention. Cavitation bubbles imploding in biological environments are known for their mechanical effects on cells and tissue. In this study, visual and acoustic monitoring was applied to characterize and quantify cavitation phenomena around longitudinally or flexurally oscillating core needle biopsy needles, when immersed in deionized water or embedded in agarose-based tissue mimicking phantom. In water, we observed that cavitation was most prominent with side cut needle, but bubble activity was also present with front cut needle. In agarose, the intensity of the cavitation was found to decrease with increasing agarose concentration. Cavitation was still observed at 0.3% w/v agarose gel, but at 1.0% w/v gel, cavitation activity was essentially eliminated. Acoustic emission was observed with both needle types from audible to ultrasound ranges. The study suggests that cavitation as a physical mechanism can occur in operation of spring-loaded core needle biopsy devices in water and tissue-mimicking hydrogels and should be considered as an opportunity for the development of new in vivo applications related to the echogenicity of the cavitation bubbles in ultrasound imaging as well as considered as a physical mechanism for safety studies.