Ultrasonic biomicroscopy of viable, dead and apoptotic cells.

Ultrasonic imaging is frequently used in medical diagnosis to differentiate normal and tumour tissues. Here we investigate if distinct types of cell death can be discriminated through the use of ultrasound biomicroscopy. By using a well-controlled system in vitro, we demonstrate that this imaging modality can be used to differentiate living cells, dead cells and cells that have died by programmed cell death or apoptosis. The results indicate a greater than twofold ultrasound backscatter signal from apoptotic cells in comparison to viable cells, whereas heat-killed cells exhibit an intermediate level of ultrasound backscatter. The results have potential implications in the study of disease-related biological processes involving apoptosis.