Histotripsy means "cell pulverizing". We know disruption (pulverization or otherwise) of a tumor bed tends to incite a local inflammatory reaction, and a brisk inflammatory reaction seems to correlate with survival. So the idea here seems to be an extension of high energy ultrasound methods developed for lithotripsy (breaking up kidney stones) to disrupt tumor beds. Not something I'd want for a pre-cancerous lesion, but if it's stage 4 liver mets ... sure. Have at it.