Ultrasound imaging of apoptosis: high-resolution non-invasive monitoring of programmed cell death in vitro, in situ and in vivo

A new non-invasive method for monitoring apoptosis has been developed using high frequency (40 MHz) ultrasound imaging. Conventional ultrasound backsc atter imaging techniques were used to observe apoptosis occurring in respon se to anticancer agents in cells in vitro, in tissues ex vivo and in live a nimals. The mechanism behind this ultrasonic detection was identified exper imentally to be the subcellular nuclear changes, condensation followed by f ragmentation, that cells undergo during apoptosis. These changes dramatical ly increase the high frequency ultrasound scattering efficiency of apoptoti c cells over normal cells (25- to 50-fold change in intensity). The result is that areas of tissue undergoing apoptosis become much brighter in compar ison to surrounding Viable tissues. The results provide a framework for the possibility of using high frequency ultrasound imaging in the future to no n-invasively monitor the effects of chemotherapeutic agents and-other antic ancer treatments in experimental animal systems and in patients. (C) 1999 C ancer Research Campaign.